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A.  I.  Levors^ft 


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HARPER  &  BROT 


WORLD 


PL. I 


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IWnmbr  A.Viulkaa 


P.S.  NEW  YORK 


THE   EARTH: 

A  DESCRIPTIVE  HISTORY  OF  THE 

PHENOMENA  OF  THE  LIFE  OF  THE  GLOBE. 


By  ELISEE  rectus. 

Translated  by  the  late  B.  B.  WOODWARD,  M.A., 

AND 

Edited  by   HENRY  WOODWARD,  British  Museum. 

ILL  us  TR A  TED 

BY 

TWO  HUNDRED  AND  THIRTY  MAPS  INSERTED  IN  THE  TEXT, 
AND  twenty-three  PAGE  MAPS  PRINTED  IN  COLORS. 


NEW    YORK: 
HARPER    &    BROTHERS,    PUBLISHERS, 

FRANKLIN    SQUARE. 
I87I. 


^^7 


PUBLISHER'S  ADVERTISEMENT. 

Tras  work — translated  by  the  late  B.  B.  Woodward,  Esq.,  B.A.  Lond., 
F.S.A.,  the  Queen's  Librarian  at  Windsor  Castle,  in  his  leisure  hours, 
and  edited,  since  his  death,  by  his  brother — is  the  result  of  more  than 
fifteen  years'  careful  study,  travel,  and  research,  by  one  of  the  most  able 
li\dng  French  authors,  Elisee  Reclus.  It  has  already  passed  through 
two  French  editions,  and  the  pages  of  the  present  volume  have,  from 
time  to  time,  received  the  benefit  of  the  Author's  attention.  There  is 
no  work,  either  French  or  English,  in  which  so  great  a  task  has  been 
attempted,  and  achieved  with  such  wonderful  success.. 

The  illustrations,  both  in  number  and  excellence,  surpass  diose  of 
any  similar  work  upon  Physical  Geography.  ^B 

The  careful  and  laborious  research  displayed  in  the  elaboration  and 
completion  of  each  portion  of  the  book,  and  the  harmonious  manner 
in  which  the  several  parts  are  united,  must  insure  for  M.  Keclus  an  hon- 
orable place  in  popular  scientific  literature. 


CONTENTS. 


PART  I. 

THE  EARTH  AS  A  PLAJJET. 


Chapter  I. — Smallness  of  the  Earth  as  compared  with  the  Sun  and  Fixed  Stars ;  Grand- 
eui*of  its  Phenomena. — Form  of  the  Terrestrial  Globe ;  its  Dimensions 13 

Chapteb  II.  — Motion  of  the  Planet.  — Diurnal  Rotation  and  Annual  Revolution. — Si- 
dereal and  Solar  Day. — Succession  of  Days  and  Seasons. — Difference  of  Duration  of 
the  Seasons  in  the  Two  Hemispheres. — Precession  of  the  Equinoxes. — Nutation. — 
Planetary  Perturbations. — Movement  of  the  Earth  towards  the  Constellation  Her- 
cules       16 

Chapter  III. — Various  Opinions  as  to  the  Formation  of  the  Earth. — Laplace's  Hypoth- 
esis ;  grave  Objections  raised  to  it. — Theory  of  a  Central  Fire ;  Objections  to  it. 24 

Chapter  FV. — Geological  Strata. — Conglomerates. — Sandstones. — Clays. — Limestones. 
— Fossiliferous  Beds. — Sequence  of  Organic  Beings. — General  Classification  of  Strata. 
— Duration  of  Geological  Periods .* 32 

Chapter  V. — Incessant  Modification  in  the  Shape  of  Continents. — ^Attempts  made  to 
learn  the  former  Distribution  of  Soils  and  Climates. — Object  of  Geology. — Province 
of  Physical  Geography 39 


PART  II. 

THE  LAND. 
Chapter  VI.  — Regular  Distribution  of  Continents.  — Ideas  of  Ancient  Nations  on  this 
Point. — Hindoo  Legends. — Atlas  and  the  Giant  Chibchacum. — Homer's  Shield. — 
Strabo 46 

Chapter  VII. — Inequality  of  Land  and  Water. — The  Oceanic  Hemisphere. — ^The  Sem- 
icircle of  Land. — Distribution  of  the  highest  Plateaux  and  loftiest  Mountain  Chains 
round  the  Indian  and  Southern  Oceans. — Pokr  Circle. — Circle  of  Lakes  and  Deserts. 
— Coasts  arranged  in  Arcs  of  a  Circle. 50 

Chapter  VIII. — Division  of  the  Land  into  the  Old  and  Ne^rWorlds. — Double  American 
Continent. — Double  Continent  of  Europe  and  Africa. — Double  Continent  of  Asia  and 
Australia 59 

Chapter  IX. — Principal  Analogies  between  Continents. — Pyramid  Form  of  Portions  of 
the  World. — Slopes  and  Declinties.  —  Closed  Basins  of  each  Continent. — Southern 
Peninsulas  in  each  Group  of  Continents. — Hypothesis  of  Periodical  Deluges. — Rhyth- 
mical Arrangements  of  Peninsulas •   64 

Chapter  X. — Numerous  Indentations  of  the  Northern  Continent. — Heaviness  of  Form 
in  the  Southern  Continents. — Inequality  of  Size  in  the  Continents  of  the  Old  World. — 
Extent  of  Coast-line  in  Inverse  Ratio  to  the  Area  of  Land. — Contrasts  between  the 
Old  World  and  the  New. — The  Transverse  Position  of  the  Axes  of  America  and  the 
Old  World, — Contrasts  of  Climate  in  the  various  Continents;  North  and  South,  East 
and  West 69 


yi  CONTENTS. 

Pago 

Chapter  XI. — Harmony  of  Shape  in  Oceans. — The  two  Basins  of  the  Pacific. — The  two 
Bq^s  of  the  Atlantic. — The  Arctic  Frozen  Ocean  and  the  Antarctic  Continent. — Con- 
trasts, an  Essential  Condition  of  Planetary  Vitality 76 

Chapter  XII.  — General  Aspect  of  Plains. — Alluvial  Plains. — Cultivated  Plains.  — Uni- 
formity in  Uncultivated  Plains. — Varieties  in  Appearance  produced  by  Climates  and 
different  Physical  Conditions * 78 

Chapter  XIII.— The  French  Landes — The  Brandes  and  the  Alios. — The  Campine. — 
The  Heaths  of  Holland  and  Northern  Germany.  —  The  Puszta  of  Hungary. — The 
Grassy  Steppes  of  Russia. — The  Salt  Steppes  of  the  Caspian  and  the  Aral. — The  Tun- 
dras      81 

Chapter  XTV, — Semicircle  of  Deserts  parallel  to  the  Semicircle  of  Landes  and  Steppes. — 
The  Sahara. — Sands,  Rocks,  Oases. — The  Deserts  of  Arabia. — The  Nefoud. — Deserts 
of  Iran  and  the  Indus. — The  Desert  of  Cobi ••     90 

Chapter  XV. — Plains  and  Deserts  of  the  New  World.  — Humidity  of  the  American 
Continents. — Distribution  of  Savannahs  and  sterile  Tracts. — The  Prairies  of  North 
America. — The  Llanos  and  Pampas 97 

Chapter  XVI. — American  Deserts. — The  Great  Basin  of  Utah.— The  Desert  of  Colo- 
rado.— The  Atacama  and  the  Pampa  of  Tamarugal. — Deposits  of  Salt,  Saltpetre,  and 
Guano 102 

Chapter  XVII. — Difference  between  Plateaux  and  Plains. — Material  Importance  of 
Plateaux  in  the  Economy  of  the  Globe. — Distribution  of  elevated  Regions  on  the  Sur- 
face of  Continents * . .   107 

Chapter  XVIII. — The  Great  Plateaux  of  Central  Asia  and  the  Gate  of  the  Hindoo 
Kutch.  — Plateaux  of  Europe.  —  Their  symmetrical  Arrangement.  — Plateaux  of  the 
two  Americas. — Similarity  between  the  closed  Basin  of  Bolina  and  the  District  of 
Utah. — Plateaux  of  Africa Ill 

Chapter  XIX. — Isolated  Mountains. — Mountains  in  Groups. — Chains  and  Systems  of 
Mountains.  —  The  Beauty  of  Mountain  Peaks.  —  Sacred  Mountains.  —  Pleasures  of 
Mountain  Climbers 117 

Chapter  XX.  — Various  Forms  of  Mountains. — Poverty  of  polished  Languages  in  de- 
scribing their  Appearance. — Richness  in  this  respect  of  the  Spanish  Language  and 
the  Alpine  and  Pyrenean  Patois. — The  numerous  Provincial  Terms  employed  for  va- 
rious Shapes  of  Hills  and  Mountains ., 122 

Chapter  XXI. — Inequalities  and  Depressions  in  the  Vertical  Outline  of  Mountains.  — 
Origin  of  Valleys,  Gorges,  and  other  Depressions. — Longitudinal  Valleys. — Transverse 
Valleys. — Winding  Valleys  with  Parallel  Sides. — ^Valleys  with  Defiles  and  Gradations 
of  Levels, — Cluses  and  Caflons. — General  Arrangement  of  Valleys. — Amphitheatres. 
— The  Oules  of  the  Pyrenees..  j| 129 

Chapter  XXII.  —  Depressions  in  Mountain  Ridges. — Diversity  in  the  Form  of  Passes 
(Cols). — Relation  between  the  respective  Altitudes  of  Summits  and  Passes. — Law  of 
Debouchments.— Real  and  Ideal  Slopes  of  Mountains.— Estimated  Solid  Contents  of 
Mountain  Groups 13.=; 

Chapter  XXIII. — Hypotheses  as  to  the  General  Laws  of  Mountain  Chains. — M.  Elie 
de-Beaumont's  Theory  of  Parallel  Upheavals. — Chain  of  the  PjTenees  taken  as  a  Type 
of  the  Cordilleras  or  Longitudinal  Chain. — Various  Irregularities  in  the  Chain. — The 
Pyrenees  as  an  Ethnological  Barrier 139 

Chapter  XXTV. — Mountains  of  Central  Europe. — Contrast  between  the  Alps  and  the 
Jura. — The  Jura  as  a  Type  of  a  System  of  Mountains  with  Parallel  Chains. — Appar- 
ent Chaos  of  the  Alps. — Central  Group  of  St.  Gothard. — Groups  of  Monte  Rosa  and 
Mont  Blanc. — The  Alps  considered  as  a  Frontier. 1 44 


CONTENTS.  Vii 

?■(• 
Chapter  XXV. — Mountain  Chains  of  Central  Asia. — The  Konen-Lun,  the  Karakorum, 

the  Himalaya. — The  South  American  Andes,  a  Type  of  the  Bifurcated  Chain 151 

Chapter  XXVI. — Gradual  Cooling  of  the  Air  on  Mountain  Sides. — DiflSculty  of  Ascents. 
— Limits  of  Man's  Habitation. — Illness  felt  by  Mountain  Travelers 156 

Chapter  XXVII. — Gradual  Subsidence  of  Mountains  during  the  Lapse  of  Ages. — Sud- 
den Downfalls  and  Chaos. — The  Fall  at  Felsberg. — Slow  Action  of  Meteoric  Agencies  159 


PART   IIL 

THE  CIRCULATION  OF  WATER. 

Chapter  XXVIII.  — Snow-fall  on  Mountains.  — Lower  Limit  of  Snow.  — Zone  of  Per- 
petual or  Permanent  Snow , 162 

Chapter  XXIX. — Influence  of  the  Sun  and  Meteoric  Agents  on  the  Snow. — Avalanches. 
— Protecting  Forests. — Defensive  Works  against  Downfalls  of  Avalanches 168 

Chapter  XXX.— Gradual  Transformation  of  Snow  into  Ice. — NeVes,  or  Glacier-reser- 
voirs. — rtienomenon  of  Regelation . — Crystals  of  Ice.  —Glaciers  of  the  First  and  Second 
Order 173 

Chapter  XXXI. — Movement  of  Glaciers. — Experiments  and  Theories. — Convexity  of 
the  Central  Part  of  a  Glacier. — Its  successive  Windings. — Friction  of  the  Ice  against 
the  Bottom  and  Sides  of  the  Bed. — The  Glacier  Gauge.— Inclination  of  the  Glacier  Bed  177 

Chapter  XXXII.  —  Marginal,  Transversal,  and  Longitudinal  Crevasses.  -^  Seracs.  — 
Moulins. — Bridges  of  Snow. — Veins  of  fresh  Ice. — Surface-streams  on  Glaciers. — 
Gouilles. — Lakes  and  Inundations. — Discharging  Channels 183 

Chapter  XXXIII. — De'bris  lying  on  the  Surface  of  the  Glacier. — Holes  in  the  Surface. 
—  Glacial  Tables.  —  Moraines;  Lateral,  Medial,  and  Frontal. — Ribbons  of  Mud. — 
Measurement  of  the  Speed  of  Glaciers. — Ablation. — Sub-glaciary  Streams. — Terminal 
Arches. — Contrast  between  the  Glacier  Ice  and  the  surrounding  Vegetation 192 

Chapter  XXXIV. — Progress  and  Retirement  of  Glaciers. — Appearance  of  the  Bed 
when  abandoned  by  the  Ice. — Roches  Moutonn^es. — Parallel  Furrows 201 

Chapter  XXXV.— Distribution  of  Glaciers  over  the  Surface  of  the  Earth 206 

Chapter  XXXVI. — Jhe  Glacial  Period. — Ancient  Glaciers  of  Europe.— Dispersion  of 
Rocks  and  Boulders  from  Scandinavia  and  in  North  America. — Ancient  Glaciers  in 
Tropical  Regions : 216 

Chapter  XXXVII. — Secondary  Part  taken  by  Glaciers  in  the  Circulation  of  Water. —       . , 
Mountain  Flood-waters. — Absorption  of  Rain  and  melted  Snow  by  the  Earth,  Peat- 
mosses, and  Rocks. — Springs  and  their  Nymphs 222 

Chapter  XXXVIII. — Variation  in  the  Discharge  of  Springs. — Estavelles. — Equaliza- 
tion of  the  Supply  in  Springs  with  deep  Sources. — Intermittent  Springs 227 

Chapter  XXXIX. — Ascending  Springs. — Artesian  Wells. — Temperature  of  Jetting 
Springs 231 

Chapter  XL.— Cold  and  Thermal  Springs 234 

Chapter  XLI. — Mineral  Springs. — Incrusting  Springs. — Metallic  Veins. — Salt  Springs  238 

Chapter  XLII. — Subterranean  Rivers. — The  Spring  of  Vaucluse,  the  Tonvre. — Sub- 
marine Affluents.— The  Rios  of  Yucatan. — The  "Mud-lumps"  of  the  Mississippi 246 

Chapter  XLIII. — System  of  Subterranean  Streams. — Joints  and  Fissures  of  Rocks. — 
Stalactites.- The  Inhabitants  of  Cares. — The  Mammoth  Cave. — Caverns  of  Camiola 
and  Istria 251 


viii  CONTENTS. 

P»ge 

Chapter  XLIV. — Eivers. — Various  Denominations  ofWater-courses. — Determination 
of  the  principal  Branch  among  the  Affluents  of  a  River.  —  River  Basins  and  Water- 
sheds.— Forks  of  certain  Rivers 261 

Chapter  XLV. — The  Hydrographical  Systems  of  various  Parts  of  the  World 271 

Chapter  XL VI. — The  River  of  the  Amazons. — Diversity  in  the  Character  of  Water- 
courses. —  Unity  of  the  Law  which  governs  them.  —  Equalization  of  their  Slopes.  — 
Upper,  Middle,  and  Lower  Courses  of  liivers 279 

Chapter  XLVII. — Mountain  Torrents. — Inequalities  of  their  Beds  and  of  their  Dis- 
charge of  Water. — Temporary  Streams. — Filling  up  of  Lakes. — Erosions,  Gorges,  and 
Slopes. — Torrents  of  the  French  Alps 284 

Chapter  XL  VIII.  — Erosion  of  Lacustrine  Dikes. — Cataracts  and  Rapids 296 

Chapter  XLIX. — Formation  of  Islands. — Reciprocity  of  Curves. — Windings  and  Cut-* 
tings. — Shifting  of  the  Courses  of  Affluents 306 

Chapter  L.^— Periodical  Rising  of  Streams.  —  "Embarras"  of  Floating  Trees. — Ice- 
floods  in  the  Northern  Rivers. — Inundations 317 

Chapter  LI. — Means  of  Preventing  Floods. — Natural  and  Artificial  Reservoirs. — Irri- 
gation Channels — Embankments,  and  Cracks  in  them. 325 

Chapter  LII. — The  Mouths  of  Rivers. — Estuaries. — Long  Banks  of  Sand. — Deltas. — 
Network  of  Branches  of  Rivers  in  Alluv-ial  Plains 339 

Chapter  LIII. — The  Channels  of  the  Mississippi.  —  "Working  Rivers." — Shifting  of 
the  Point  of  Bifurcation. — Raising  of  the  River-bed  above  the  Delta. — Alteration  in 
the  Situation  of  the  Mouths  of  Rivers 349 

Chapter  LI V.— Bars  of  Rivers. — Operations  undertaken  for  Deepening  the  Mouths  of 
Rivers 363 

Chapter  LV. — Alteration  in  the  Position  of  Water-courses  in  Consequence  of  the  Ro- 
tation of  the  Earth. — Masses  of  Water  brought  down  to  the  Sea  by  Rivers. — General 
Considerations 372 

Chapter  LVI. — Lakes. — Formation  of  Lakes. — Their  Increase  and  Diminution. — Their 
Form  and  their  Depth. — Lakes  lying  in  Successive  Gradation  of  Elevation 383 

Chapter  LVII. — Various  Phenomena  in  Lakes. — Color  of  their  Waters. — Seiches. — 
Currents  and  Tides. — Formation  of  Ice  in  Lakes 394 

Chapter  LVIII. — Lakes  acting  as  Regulators  of  the  Rivers  which  pass  through  them, 
— Fresh-water  and  Salt-water  Lakes. — The  Caspian  Sea 399 

Chapter  LIX. — The  Dead  Sea. — The  Salt  Lakes  of  Asia  Minor  and  the  Russian  Steppes, 
—The  Great  Salt  Lake.— The  Melr'ir 407 

Chapter  LX. — Marshes. — Swamps  of  North  America. — Peat-bogs. — Unhealthiness  of 
Marshes 413 


PART   IV. 

SUBTERRANEAN  FORCES. 
Chapter  LXI.— Eruptions  of  Etna  in  the  Year  1865.— Mutual  Dependence  of  all  Ter- 
restrial Phenomena 419 

Chapter  LXII. — Sea-coast  Line  of  Volcanoes. — The  Pacific  "Circle  of  Fire." — Vol- 
canoes of  the  Indian  Ocean ;  of  the  Atlantic ;  of  the  Mediterranean ;  of  the  Caspian ; 
of  Central  Asia ." 426 

Chapter  LXIII. — Torrents  of  Steam  escaping  from  Craters. — Gases  produced  by  the 
Decomposition  of  Sea-water. — Hypotheses  as  to  the  Origin  of  Eruptions. — Independ- 
ence of  the  several  Volcanic  Outlets 433 


CONTENTS.  JX 

•  p«g» 

Chapter  LXIV. — Grow-th  of  Volcanoes. — Theories  of  Humboldt  and  Leopold  von  Buch 

as  to  the  Upheaval  of  Craters. — Disagreement  of  these  Theories  with  the  Pacts  obsened  440 

Chapter  LXV. — Number  and  Arrangement  of  Volcanic  Outlets. — Form  of  Volcanic 
Cones  and  Craters 445 

Chapter  LX VI. — Compositioa  of  Lavas  ;  Trachytes:  Pumice-stone;  Obsidian;  Ba- 
salts ;  Basaltic  Colonnades 453 

Chapter  LXVII. — Sources  of  Lava ;  Stromboli ;  Masaya ;  Isalco ;  Kilanea. — Lateral 
Crevices  in  Volcanoes. — Eruption  and  Motion  of  Lava 458 

Chapter  LXVIIL — Volcanic  Projectiles. — Explosions  of  Ashes. — Subordinate  Volca- 
noes.— Mountains  reduced  to  Dust. — Flashes  and  Flames  proceeding  from  Volcanoes  468 

Chapter  LXIX. — Streams  of  Mud  ejected  by  Craters. — Mud  Volcanoes. 475 

Chapter  LXX. — Volcanic  Thermal  Springs. — Geysers. — Spring  in  New  Zealand. — 
Fumerolles. — Solfataras. — Craters  of  Carbonic  Acid 480 

Chapter  LXXI. — Submarine  Volcanoes 489 

Chapter  LXXIL — Periodicity  of  Eruptions. — Influence  of  Temperattu^  on  Volcanic 
Phenomena. — Extinction  of  Furnaces  of  Lava 497 

Chapter  LXXIII. — Earthquakes. — Vibrations  of  the  Ground. — Various  Hypotheses . .  500 

Chapter  LXXIV. — Earthquakes  of  Volcanic  Origin. — Subterranean  Downfalls. — Ex- 
plosions of  Mines  and  Powder-mills 503 

Chapter  LXXV.  —  Great  Catastrophes.  —  Earthquake  at  Lisbon.  —  Area  of  Disturb- 
ance.— Earth(iuakes  at  Sea 507 

Chapter  LXXVI.  —  Movement  of  Terrestrial  Waves. — Variations  caused  by  the  In- 
equality of  Vertical  Outline  and  the  Diversity  of  Rocks.  —  Areas  of  Disturbance.  — 
Noise  of  Earthquakes. — Fright  of  Men  and  Animals 511 

Chapter  LXXVII. — Secondary  Effects  of  Shocks. — Springs. — Jets  of  Gas. — Fissures. 
— Depressions  and  Elevations  of  the  Ground 519 

Chapter  LXXVIII.  — Periodicity  of  Earthquakes.  — The  Maximtim  in  Winter.  — The 
Maximum  at  Night.  —  Coincidence  with  Hurricanes.  —  Influence  of  the  Heavenly 
Bodies, 623 

Chapter  LXXIX.  —  Slow  Oscillations  of  the  Ground.  —  Difficulties  presented  in  the 
Observation  of  these  Phenomena. — Causes  of  Error :  Erosion  of  Shores,  Swelling  and 
Sinking  of  Peaty  So'ils. — Influence  of  Temperature. — Local  Upheavals 527 

Chapter  LXXX.  —  Upheaval  of  the  Scandinavian  Peninsula ;  of  Spitzbergen ;  of  the 
Coasts  of  Siberia ;  of  Scotland ;  of  Wales 531 

Chapter  LXXXI.— Upheaval  of  the  Mediterranean  Regions. — Former  Libyan  Strait. 
— Coasts  of  Tunis,  Sardinia,  Corsica,  Italy,  and  Western  France 538 

Chapter  LXXXII. — Coasts  of  Asia  Minor. — Ancient  Ocean  of  Hyrcania. — Coasts  of 
Palestine  and  Egypt.  —The  Adriatic  Gulf. 542 

Chapter  LXXXIII.— Subsidence  of  the  Shore  of  the  Channel,  of  Holland,  of  Schleswig, 
of  Prussia 546 

Chapter  LXXXIV. — Upheaval  of  the  Coasts  of  Chili  and  Peru. — Probable  Depression 
of  the  Coasts  of  l^  Plata  and  Brazil. — Coasts  of  North  America  and  Greenland 550 

Chapter  LXXXV.  — Reefs  of  the  South  Sea.  — Darwin's  Theory  as  to  Upheavals  and 
Depressions 556 

Chapter  LXXXVI.— The  Great  Areas  of  Upheaval  and  Depression.— Mobility  of  the 
so-called  Rigid  Crust  of  the  Earth 562 


LIST  OF  COLORED  ILLUSTRATIONS. 


rLAT*  nam 

I.  Map  op  the  World : . . .  Frontispiece. 

II.  Geological  Chart  op  the  World To/ace  paye    13 

m.  Geological  Map  op  England 37 

IV.  North  America 52 

V.  South  America 58 

VI.  Europe 63-64 

VII.  Africa 66-67 

VIII.  Asia 70-71 

IX.  Australia  aot)  the  adjacent  Archipelago , ^ 72-73 

X.  The  Alps 148-149 

XI.  The  Mer  de  Glace  and  its  Affluents 178 

XII.  Glaciers  op  Geisberg  and  Rothmoos 194 

XIII.  Glaciers  of  Langthal  and  Gubol 201 

Xrv.  Glacier  of  Vernagt 204 

XV.  Former  Glaciers  op  the  Vallet  op  the  Adige 211 

XVI.  Middle  Course  of  the  Mississippi 311 

XVII.  Delta  op  the  Ganges 353 

XVIII.  Lake  Garda 388 

XIX.  The  Bugors  op  the  Caspian  Sea *. 405 

XX.  Eruptions  op  Etna ■. 425 

XXI.  Volcanoes 432 

XXII.  Upheavals  and  Depressions 527 

XXIII.  Atoll  Abi 560 


.' 


CEOLOGJCAL  CHt 


Di-awn  by  A.VtrilJeinin 


HARPER  &  EROTI 


OF  THE  WORLD 


Pi..  11 


NSW  YORK 


Fng^byia-hard. 


THE  EARTH. 

PART   I. 
THE  EARTH  AS  A  PLANET. 

CHAPTER  I. 

SMALLNESS  OF  THE  EARTH  AS  COJIPARED  WITH  THE  SUN  AND  FIXED  STARS  ; 
GRANDEUR  OF  ITS  PHENOMENA. — FORM  OF  THE  TERRESTRIAL  GLOBE  ;  ITS 
DIMENSIONS. 

The  earth  on  which  we  dwell  is  one  of  the  lowest  in  rank  among  the 
heavenly  bodies.  If  an  astronomer  in  some  other  planet  were  exploring 
the  immensity  of  space,  our  earth,  owing  to  its  small  size,  might  readily 
elude  his  intelligent  view.  A  mere  satellitje  of  the  sun,  the  volume  of 
which  is  1,255,000  times  greater,  the  earth  is  but  a  point  as  compared 
with  thejmmense  tract  of  ether  traversed  by  the  planets  in  their  courses 
round  their  central  globe.  The  sun  itself  is  only  a  spark,  which  seems 
lost  amid  the  eighteen  millions  of  stars  which  Herechel's  telescope  dis- 
cerned in  the  Milky  Way ;  the  latter,  an  immense  agglomeration  of  suns 
and  planets,  which  looks  to  us  like  a  broad  streak  of  light  round  the  whole 
universe,  is  in  reality  nothing  but  a  nebula ;  that  is,  a  cloud  of  stars  re- 
sembling a  mist,  which  would  be  as  nothing  in  infinite  space.  Beyond 
our  own  sky,  other  skies  stretch  far  away  into  infinity,  and  others  beyond 
these,  so  that  light,  notwithstanding  its  prodigious  rapidity,  takes  eterni- 
ties to  cross  them.  How  small  the  earth  seems  in  this  fathomless  abyss 
of  stars !  Individually,  it  may  seem  immense  to  us ;  all  too  vast  for  our 
littleness,  we  have  not  yet  succeeded  in  investigating  the  whole  of  its  sur- 
face ;  but,  as  compared  with  the  whole  sidereal  cosmos,  it  is  less  than  a 
grain  of  sand  by  the  side  of  a  mass  of  mountains,  or  an  atmospheric  par- 
ticle compared  with  aerial  space. 

True  enough  that  the  earth  is  nothing  but  an  almost  impalpable  grain 
of  dust  to  the  vision  of  the  astronomer  scanning  the  nebulae  in  the  field 
of  his  telescope,  but  it  is,  nevertheless,  quite  as  much  worthy  of  study  as 
any  other  of  the  heavenly  bodies.  If  it  does  not  possess  magnitude  of  di- 
mensions, it  presents  an  infinite  variety  in  all  its  details.  Whole  genera- 
tions, living  one  after  the  other  upon  its  face,  might  pass  their  lives  in 


14  THE  EARTH  AS  A  PLANET. 

Studying  its  phenomena  without  comprehending  all  their  full  beauty. 
There  is  not  even  any  special  science,  having  for  its  aim  some  portion  of 
the  terrestrial  surface  or  some  particular  series  of  its  products,  which  does 
not  present  to  our  savants  an  inexhaustible  field  of  inquiry.  Moreover,  is 
not  our  little  globe,  as  well  as  the  sky,  a  real  cosmos,  both  by  the  admira- 
ble arrangement  of  its  parts,  and  by  its  supreme  harmony  as  a  whole  ?  In 
a  certain  point  of  view,  is  not  our  almost  imperceptible  planet  as  great  as 
the  universe,  in  that  it  is  the  expression  of  the  same  laws  ?  In  the  form 
of  its  orbit,  in  its  movements  round  the  sun  and  on  its  own  axis,  in  the 
succession  of  days  and  seasons,  and  in  all  the  phenomena  governed  by  the 
great  law  of  attraction,  the  earth  becomes  the  representative  of  all  the 
other  planets ;  in  studying  it,  we  study  all  the  heavenly  bodies. 

Our  planet  is  a  spheroid ;  that  is,  a  sphere  flattened  at  the  two  poles 
and  enlarged  at  the  equator,  so  that  all  the  circles  passing  through  the 
extremity  of  the  polar  axis  form  ellipses.  The  presumed  depression  of 
each  pole  is  about  thirteen  miles,  nearly  a  three-hundredth  part  of  the  ra- 
dius of  the  earth  ;*  but  it  is  not  altogether  certain  that  the  two  poles  are 
equally  flattened.  Perhaps  a  contrast  exists  between  the  two  hemispheres, 
liot  only  in  the  features  of  their  continents  and  the  distribution  of  seas, 
but  also  in  their  geometrical  shape.  Be  this  as  it  may,  it  appears  to  be 
proved  that  the  curvature  is  not  exactly  the  same  at  all  points  of  the 
earth  at  an  equal  distance  from  the  poles ;  the  meridians  appear  without 
exception  to  be  irregular  ellipses.  The  recent  measurement  of  degrees 
carried  out  by  astronomers,  and  especially  the  great  trigonometrical  sur- 
vey made  between  1816  and  1852,  under  the  direction  of  Struve,  from  the 
coasts  of  the  Frozen  Ocean  to  the  banks  of  the  Danube,  have'disclosed 
some  singular  deviations  in  the  form  of  the  earth,  caused  either  by  the 
geological  nature  of  the  crust  or  by  the  vicinity  of  considerable  mountain 
chains.  Thus,  among  the  countries  of  Europe,  the  surfaces  of  England 
and  Italy  are  sensibly  depressed  in  comparison  with  adjacent  countries. 

These  inequalities  of  curvation,  which  are  doubtless  variable,  and  cor- 
respond to  the  changes  in  the  position  of  the  earth's  centre  of  gravity,  are 
cognizable  only  by  the  astronomer,  and  nowhere  interrupt  the  apparent 
horizontal  character  of  the  surface  of  plains  and  seas.  As  far  as  man  is 
concerned,  the  roughness  and  hollows  forming  our  plains,  mountains,  and 
valleys,  are  more  important  than  any  inequalities  in  the  roundness  of  the 
globe.  According  to  Von  Schubert,  the  academician,  an  enlargement, 
perpendicular  to  the  equator,  and  therefore  parallel  to  the  meridian,  bulges 
out  all  round  the  globe,  passing  through  Europe  and  Africa ;  this  hypoth- 
esis is  not,  however,  made  good  by  the  measurements  of  an  arc  of  the  me- 
ridian recently  made  in  India. 

The  dimensions  of  the  earth,  as  we  have  already  seen,  are  almost  as 
nothing  compared  with  the  larger  celestial  bodies,  and  especially  with 
the  extent  of  space  which  can  be  explored  by  the  telescope.    If  light,  the 

*  According  to  Bessel,  the  astronomer,  299'1528.  All  possible  errors  are  embraced  be- 
tween 302-301  and  296-005. 


THE  EARTH  AS  A  PLANET.  15 

speed  of  which  has  been  adopted  in  astronomy  as  a  term  of  comparison, 
could  be  diffused  in  a  curved  line,  it  would  travel  seven  times  round  the 
globe  in  a  second  of  time;  this  standard  of  measurement,  therefore,  the 
only  one  suited  to  the  stellary  field,  is  completely  inapplicable  to  the  sur- 
face of  our  globe.  Man,  small  as  he  is  in  comparison  with  the  planet  on 
which  he  lives,  in  the  first  instance  chose  out  for  the  measurement  of  his 
domain  either  parts  of  his  own  body,  such  as  the  foot,  cubit,  or  fathom^ 
or  the  distance  traveled  during  a  certain  period  of  time,  as  the  par asanff, 
stadium,  mile,  or  league.  It  was  not  until  the  end  of  the  last  century  that 
the  savants  who  then  adorned  France  conceived  the  idea  of  dividing  the 
circumference  of  the  earth  into  equal  parts,  which  for  the  future  should 
serve  as  a  standard  of  measure  for  all  terrestrial  distances.  This  measure, 
or  nihtre,  which,  with  the  aid  of  its  multiples  and  divisions,  enables  us  to 
estimate,  with  equal  ease,  the  circumference  of  the  globe  or  that  of  an  al- 
most invisible  molecule,  is  the  ten-millionth  part  of  the  arc  described  from 
the  equator  to  one  of  the  poles.  Owing  to  errors  which  the  difficulties 
of  actual  measurements  rendered  inevitable,  the  ideal  mhtre  exceeds  the 
customary  one  by  nearly  the  eleventh  part  of  a  miUimHre  ;  but  this  very 
trifling  difference,  which  is  imperceptible  to  the  naked  eye,  may  be.  disre- 
garded in  practice  without  any  inconvenience.  A  line,  therefore,  going 
round  the  earth,  and  passing  through  the  two  poles,  would  be  of  the  length 
of  about  40  millions  of  metres,  or  40,000  kilometres.  Thus,  as  Schubert* 
remarks,  it  is  about  the  distance  which  the  usual  pace  of  a  man  would 
travel  over  in  a  year — that  is,  if  he  ^id  not  stop  for  a  single  instant.  The 
superficies  of  the  globe,  as  calculated  by  Wolfers,  according  to  the  most 
recent  measurements  which  astronomers  have  made  of  the  arcs  of  the  lon- 
gitude and  latitude  in  various  countries,  is  197,124,000  square  miles.  Ac- 
cording to  Encke,  the  astronomer,  it  amounts  to  197,108,580  square  miles, 
and  the  planetary  mass  would  attain  to  a  bulk  of  256,000  millions  of  cubic 
miles.  • 

*  Geachichte  der  Stele.  X/ 


IQ  THE  EARTH. 


CHAPTER  n. 

MOTION  OF  THE  PLANET. — DIURNAL  ROTATION  AND  ANNUAL  REVOLUTION. 

SIDEREAL  AND  SOLAR  DAY. — SUCCESSION  OF  DAYS  AND  SEASONS. — DIF- 
FERENCE  OF  DURATION  OF  THE   SEASONS  IN  THE   TWO   HEMISPHERES. 

PRECESSION  OF  THE  EQUINOXES. NUTATION. — PLANETARY  PERTURBA- 
TIONS.— MOVEMENT  OF  THE  EARTH  TOWARD  THE  CONSTELLATION  HER- 
CULES. 

The  isolated  globule  in  the  immensity  of  space  which  we  call  the  earth 
is  not  motionless,  as  the  ancients  necessarily  supposed,  looking  upon  it,  as 
they  did,  as  the  immovable  base  of  the  firmament  of  heaven.  Hurried  on 
in  the  vortex  of  universal  vitality,  our  globe  is  ever  actuated  by  ceaseless 
motion,  describing  in  ether  a  series  of  elliptic  spirals  so  complicated  that 
astronomers  have  not  yet  been  able  to  calculate  their  various  curves.  Be-  • 
sides  rotating  on  its  own  axis,  the  earth  describes  an  ellipse  round  the  sun, 
and,  under  the  influence  of  this  body,  is  drawn  along  from  one  heaven  to 
another  toward  distant  constellations.  It  also  oscillates  and  rocks  on  its 
axis,  and  deviates  moi*e  or  less  from  its  path,  to  salute,  as  it  were,  every 
heavenly  body  which  meets  it.  It  is  probable  that  it  never  passes  a  sec- 
ond time  through  the  same  regions  of  the  air;  yet,  if  it  has  again  to  trav- 
erse the  spiral  line  of  ellipses  it  has  already  described,  it  would  be  after  a 
cycle  of  so  many  thousands  of  millions  of  years,  that  the  earth  itself,  com- 
pletely transformed,  would  be  no  longer  the  same  planet.  Nature,  immu- 
table in  its  laws,  but  forever  variable  in  its  phenomena,  never  repeats  itself 

The  motion  of  the  earth,  the  immediate  effects  of  which  are  the  most 
obvious  to  the  notice  of  men,  is  the  daily  rotation  which  takes  place  round 
an  ideal  axis  passing  through  the  two  poles.  The  globe  turns  from  right 
to  left,  or  from  west  to  east — that  is,  in  a  contrary  direction  to  the  appa- 
rent motion  of  the  sun  and  stars,  which  seem  to  rise  in  the  east  and  to  set 
in  the  west.  As  the  earth's  axis  terminates  at  each  pole,  there  is  least 
surface-motion  at  those  points,  and  the  motion  is  .the  more  rapid  in  any 
part  of  the  sui-face  of  the  globe  the  farther  it  is  from  the  central  axis.  At 
St.  Petersburg,  in  60°  latitude,  the  speed  of  rotation  is  about  nine  miles  a 
minute ;  in  Paris,  it  exceeds  eleven  and  a  half  miles  during  the  same  brief 
time ;  on  the  equatorial  line,  which  may  be  looked  upon  as  the  ring  of  an 
immense  wheel,  the  speed  of  the  eailh  is  twice  as  great  as  it  is  at  60°  of 
latitude — that  is,  about  eighteen  miles  a  minute,  or  528  yards  a  second — 
a  rapidity  equal  to  the  flight  of  a  26-pound  cannon-ball  impelled  by  thir- 
teen pounds  of  powder.  By  means  of  this  rotatory  motion,  the  earth  pre- 
sents toward  the  sun  each  of  its  faces  alternately,  and  each  also  in  turn 
toward  the  comparatively  darker  regions  of  space;  the  succession  of  day 


MOTION  OF  THE  PLANET.  17 

and  night  is  thus  constituted.  In  addition  to  this,  the  rotation  of  the 
earth  is  an  important  fact  which  must  always  be  taken  into  account  in 
determining  the  direction  of  fluids  in  motion  on  the  surface  of  the  globe, 
such  as  streams  and  rivers,  also  marine  and  atmospheric  currents.* 

The  annual  revolution  wliich  the  earth  performs  round  the  sun  follows 
the  line  of  an  ellipse,  one  of  the  foci  of  which  is  occupied  by  the  central 
star ;  the  eccentricity  of  the  ellipse  is  nearly  equal  to  twtj  ^^  ^^^^  great 
axis.  The  distance  between,  the  sun  and  the  earth  always  varies  accord- 
ing to  the  particular  point  of  its  orbit  which  the  latter  is  traveling  over. 
At  its  aphelion.,  that  is,  at  its  greatest  remoteness,  this  distance  is  about 
93f  millions  of  miles;  at  the  period  of  its/>m/ie//o/i,  when  the  two  heav- 
enly bodies  are  nearest  to  each  other,  it  is  approximately  90,259,000  miles. 
The  mean  distance,  as  estimated  by  astronomei*s  since  the  corrections  of 
Encke,  Hansen,  Foucault,  and  Hind,  is  91,839,000  miles.  This  extent  of 
space  is  traveled  by  the  solar  rays  in  8  minutes  16  seconds;  sound  would 
take  fifteen  years  in  passing  through  the  same  distance. 

As  Kepler  has  laid  down  in  his  celebrated  laws,  our  planet  moves  with 
an  increased  rapidity  as  it  approaches  nearer  to  the  sun,  and  travels  more 
slowly  in  proportion  to  its  distance  from  that  luminary;  but  its  mean 
speed  may  be  estimated  at  nearly  19  miles  a  second,  or  sixty  times  the 
rapidity  of  a  ball  from  the  cannon's  mouth.  This  speed,  which  makes  one 
dizzy  to  think  of,  is.  to  be  added,  as  regards  each  point  in  the  surface  of 
the  earth,  to  the  rotatory  motion  which  impels  it  round  the  polar  axis. 
Modified  by  this  latter  motion,  the  line  described  by  any  one  point  on  the 
terrestrial  superfi^cies  becomes  a  spiral. 

After  having  turned  round  366  times  on  its  axis,  our  planet  has  termi- 
nated its  orbicular  course,  and  is  in  the  same  position  relatively  to  the  sun 
as  at  its  starting-point ;  it  has  then  accomplished  its  year.  During  this 
period  of  time,  composed  of  366  terrestrial  rotations,  the  sun  has  only  il- 
lumined each  hemisphere  in  turn  365  times.  How  does  this  apparent 
anomaly  arise  ?  How  does  it  happen  that  a  complete  movement  of  rota- 
tion performed  by  the  globe  round  its  own  axis  does  not  exactly  coincide 
with  the  solar  day  ?  The  cause  is  this — that  the  earth  in  its  rotation,  car- 
ried on  as  it  is  in  its  immense  orbit,  is  constantly  changing  its  position  in 
respect  to  the  sun.  As  regards  the  fixed  stars,  situate  at  an  almost  infi- 
nite distance  from  our  planet,  the  earth  remains,  so  to  speak,  always  in 
the  same  position ;  consequently,  the  sidereal  day,  that  is,  the  interval 
which  separates  two  transits  of  the  same  star  over  the  same  terrestrial 
meridian,  has  the  precise  duration  of  one  rotation  of  our  globe.  After 
each  of  its  diurnal  rotations,  our  earth  presents  to  these  far-remote  stars 
the  same  part  of  its  surface,  and  if  the  light  of  the  sun  became  suddenly 
extinct,  and  if  a  star,  such  as  Sirius  or  Aldebaran,  became  our  great  focus 
of  illumination,  our  days  would  have  the  exact  duration  of  a  terrestrial 
rotation,  that  is,  aliout  23  hours  56  minutes.  But  the  sun,  although  a 
fixed  star,  is  comparatively  near  to  the  earth.  While  the  latter  is^erform- 
*  Vide  the  chapters  as  to  "Rivers,"  "Currents,"  "The  Atmosphere,  and  Winds." 

B 


18  THE  EARTH. 


Fig.  1.  Inequality  of  the  Solar  and  Sidereal  Day. 


ing  a  movement  of  rotation,  it  alters  its  position  1,604,300  miles  along  the 
course  of  its  orbit ;  consequently,  the  sun,  in  its  apparent  progress,  seems 
to  retrograde  this  distance,  and  in  order  that  the  earth  should  present  to 
it  exactly  the  same  portion  of  its  surface  as  at  the  commencement  of  its 
rotation,  it  would  be  necessary  for  it  to  turn  round  four  minutes  more. 
The  next  day,  a  fresh  change  in  the  position  of  the  earth  again  adds  four 
minutes  to  the  duration  of  the  day,  and  so  on  till  the  end  of  the  year. 
These  daily  additions  of  four  minutes  to  the  length  of  the  day  form,  during 
a  whole  year,  a  period  equal  to  the  duration  of  one  of  the  diurnal  rotations; 
the  result  is  that  the  sidereal  days  in  the  year  exceed  the  solar  by  one.* 

Thus  the  daily  rotation  of  the  earth  round  its  axis  produces  the  succes- 
sion of  days  and  nights,  and,  in  the  same  way,  its  annual  revolution  round 
the  sun  causes  the  alternations  of  the  seasons.  If  the  axis  of  the  earth, 
that  is,  the  ideal  line  which  passes  through  its  two  poles,  were  perpendic- 
ular to  the  plane  of  its  annual  orbit,  it  is  evident  that  the  portion  of  the 
globe  lighted  by  the  sun  would  invariably  extend  from  one  pole  to  the 
other,  and  that  in  both  hemispheres  the  days  and  nights  would  always 
consist  of  twelve  hours  each.  But  this  is  not  the  case.  The  earth  per- 
forms its  revolutionary  movements  in  an  inclined  position  ;  its  ideal  polar 
axis  is  sloped  about  23°  28'  from  a  perpendicular  to  its  plane,  and  this  po- 
sition is  so  far  maintained  that  as  regards  the  comparatively  rapid  suc- 
cession of  days  and  seasons  it  may  be  looked  upon  as  invariable.     This 

*  For  a  more  complete  explanation  of  all  the  astronomioal  phenomena  relating  to  the  earth, 
we  must  refer  to  the  excellent  work  of  M.  Ame'de'e  Guillemen,  Le  Ciel.  From  this  work  we 
have  borrowed  tlie  above  plate. 


ORBIT  OF  THE  EARTH.  19 

obliquity  of  axis  causes  continued  changes  in  the  phase  presented  to  the 
sun.  The  portion  of  the  earth  illumined  by  the  rays  of  the  sun  varies 
every  day ;  for,  although  the  planetaiy  axis  may  appear  to  maintain  its 
extremity  in  a  fixed  position  as  regards  some  point  in  infinite  space,  in  re- 
spect to  the  sun  it  presents  a  constantly  varying  degree  of  inclination,  in 
consequence  of  the  continual  motion  of  the  earth.  Twice  during  the  course 
of  the  year  it  so  happens  that  the  solar  rays  fall  perpendicularly  upon  the 
equator  of  the  earth ;  at  every  other  period  in  the  annual  revolution,  some- 
times the  northern  and  sometimes  the  southern  hemisphere  receives  the 
greatest  amount  of  light. 

The  astronomical  year  commences  on  the  20th  of  March,  at  the  exact 
moment  when  the  sun  illumines  the  equator  in  a  vertical  direction,  and 
the  line  of  separation  between  light  and  shade  passes  through  the  two 
poles.  The  period  of  darkness  is  then  equal  to  that  of  light,  and  admits 
of  exactly  twelve  hours  at  all  points  of  the  earth.  Hence  the  name  of 
"  equinox"  (equality* of  nights).  But  after  this  day,  which  in  the  northern 
hemisphere  serves  as  the  starting-point  of  spring,  the  earth  continues  its 
translatory  movement.  In  consequence  of  the  inclination  of  its  axis,  tfie 
northern  hemisphere,  being  turned  toward  the  sun,  receives  a  greater  quan- 
tity of  light,  while  the  southern  half  of  the  globe  is  less  vividly  lighted. 
The  vertical  rays  of  the  sun  now  fall  more  and  more  to  the  north  of  the 
equator,  and  the  circle  of  light,  far  from  arresting  its  progress  at  the  poles, 
where  the  day  of  six  months'  duration  is  commencing  to  dawn,  extends 
far  beyond  it  over  the  regions  of  the  north.  On  the  21st  of  June,  the  day 
of  the  first  solstice,*  the  axis  of  the  earth  being  deeply  inclined  toward 
the  sun,  this  luminary  shines  on  the  zenith  of  the  tropic  of  Cancer  at  23^° 
north  of  the  equator,  and  its  light  illumines  the  whole  of  the  arctic  zone, 
that  is,  the  portion  of  the  earth's  surface  extending  to  23^°  round  the  north 
pole.  Then  spring  ceases  and  summer  begins  as  regards  the  northern 
hemisphere.  In  the  southern  hemisphere,  on  the  contrary,  autumn  is  giv- 
ing place  to  Avinter.  Above  the  equator  long  days  are  prevailing,  inter- 
rupted by  short  nights;  while  in  the  south  it  is  the  nights  which  last  the 
longest.  In  the  arctic  zone  the  sun  performs  its  apparent  course  of  diurnal 
rotation  entirely  above  the  horizon.  The  six-months'  day,  which  spring 
inaugurated  at  the  north  pole,  attains  its  high  noon  on  the  first  day  of 
summer.  At  the  same  moment  midnight  arrives  in  the  darkness  which 
is  oppressing  its  antipodes. 

Immediately  after  the  21st  of  June  all  the  phenomena  which  took  place 
during  the  preceding  season  are  directly  reversed.  The  sun  appears  to 
retrograde  toward  the  southern  horizon  ;  its  vertical  rays  cease  to  fall  on 
the  line  of  the  northern  tropic,  and  constantly  approach  the  equator.  The 
zone  of  light  in  the  northern  pole  and  of  shade  in  the  southern  equally  di- 

*  The  nsnal  tenn  "summer  solstice"  is  altogether  improper,  as  it  is  suitable  only  to  coun- 
tries in  the  northern  hemisphere.  The  summer  solstice  of  London  is  the  winter  solstice  at 
the  Ca{)e  of  Good  Hope.  The  designations  of  vernal  and  autumnal  equinox  ought  equally  to 
be  abandoned. 


^ 


20 


THE  EARTH. 


,l't'/>fr/ii//t'/- 


msM  -^p  t 


^\^*  ■^., 


lleiViiiliiT 


^oMire 


Aplii  Imn. 

.Mifjr 

f 

June 
X'Islir, 

*..,^'®^ 


April 


Fig.  2.  Orbit  of  the  Earth  around  the  Sun. 

minish,  and  the  days  shorten  in  the  northern  hemisphere  in  the  sarae  pro- 
portion as  they  lengthen  in  the  southern ;  an  equilibrium  is  gradually  be- 
ing re-established  between  the  two  halves  of  the  earth.  On  the  22d  of 
September  the  position  of  the  sun  is  again  exactly  above  the  equator,  and 
its  light  just  reaches  both  poles.  The  equinox,  or  the  absolute  equality 
of  day  and  night  in  every  part  of  the  globe,  occurs  for  the  second  time  in 
the  year;  but  this  moment  of  equilibrium  is,  so  to  speak,  but  a  mathe- 
matical point  between  the  two  seasons.  The  axis  of  the  earth  which,  dur- 
ing the  six  months  past,  turned  the  north  pole  toward  the  sun,  now  pre- 
sents to  him  the  south  pole;  the  vertical  rays  of  the  central  luminary  fall 
to  the  south  of  the  earth's  equator,  and  the  southern  hemisphere,  in  its 
turn,  is  the  best  endowed  of  the  two  halves  of  the  globe  in  the  amount  of 
light  it  receives  and  in  the  length  of  its  days.  In  the  southern  hemi- 
sphere, spring  is  commencing;  in  the  northern,  autumn.  Three  months 
afterward,  on  the  21st  of  December,  the  sun  comes  directly  over  the  south- 
ern tropic,  or  the  tropic  of  Capricorn,  23^°  south  of  the  equator,  and  the 
whole  of  the  antarctic  zone  is  presented  to  the  solar  rays.  Summer  has 
begun  in  the  southern  hemisphere,  and  at  the  same  time  winter  commences 
in  that  of  the  north.  Then,  as  the  globe  moves  on,  these  two  seasons  fol- 
low each  other  in  their  course,  until  at  length  the  earth  attains  a  position 
similar  to  that  from  which  it  started ;  the  March  equinox,  the  first  day  of 
spring  in  Europe,  and  the  first  day  of  autumn  in  Australia,  commences 
anew  the  astronomical  year. 


CHAXOES  OF  TOE  SEASONS.  21 

The  elliptical  form  of  the  earth's  orbit  and  the  unequal  pace  of  the  globe 
in  the  various  points  of  its  course  cause  some  considerable  variations  in 
the  duration  of  the  seasons.  In  fact,  from  the  20th  of  March  to  the  22d 
of  September,  that  is,  during  the  spring  and  summer  ftf  the  northern  hemi- 
sphere, the  earth  takes  1 86  days  to  travel  over  the  first  and  largest  half 
of  its  orbit,  while  during  the  winter  period,  from  the  22d  of  September  i 
to  the  20th  of  March,  only  179  days  are  required  to  accomplish  the  second  ' 
half  of  its  journey.  The  summer  period  of  the  northern  hemisphere  actu- 
ally exceeds  by  seven  or  eight  days,  or  about  187  hours,  the  correspond- 
ing period  in  the  southern  half  of  the  globe,  added  to  this,  in  consequence 
of  the  longer  space  of  time  during  which  the  arctic  pole  remains  inclined 
toward  the  sun  in  the  regions  north  of  the  equator,  the  houi-s  of  daylight 
exceed  the  hours  of  night,  while  in  the  south  the  hours  of  darkness  pre- 
dominate. This  is,  however,  to  some  extent  compensated  for ;  as,  al- 
though in  the  southern  regions  of  the  earth  the  summer  lasts  a  shorter 
time,  our  planet  is  then  closer  to  the  sun ;  it  is  at  its  perihelion,  and  con- 
sequently receives  a  larger  proportion  of  heat.  There  is,  however,  no 
doubt  about  the  fact,  as  it  is  proved  by  a  direct  observation,  both  of  the 
winds  and  currents,  and  also  of  their  various  temperatures — that,  taking 
an  equal  distance  from  the  equator,  the  southern  I'egions  are  colder  than 
those  of  the  north.  The  problem  is,  to  know  if  this  phenomenon  proceeds 
from  the  varied  distribution  of  the  continents,  or  from  the  contrast  of  sea- 
sons presented  by  the  two  moieties  of  the  earth.  On  the  whole,  does  the 
proximity  of  the  central  luminary  confer  on  *e  southern  hemisphere  as 
much  additional  caloric  as  the  opposite  hemisphei'e  gains  by  its  more  pro- 
longed exposure  to  the  solar  rays  ?  Does  it  receive  complete  compensa- 
tion ?  Not  long  ago,  most  astronomers  admitted  that  it  did ;  they  main- 
tained this,  grounding  it  on  the  calculation  that  in  each  hemisphere  the  in- 
tensity of  the  heat  is  in  the  inverse  ratio  to  its  duration.  Other  savants, 
on  the  contrary,  the  best  known  of  whom  was  Adhemar,  the  mathemati- 
cian, author  of  an  ingenious  theory  on  the  periodicity  of  deluges,  assert 
that,  in  consequence  of  the  nocturnal  radiation,  the  hemisphere  which  en- 
joys the  shorter  summer  must  necessarily  get  much  colder  than  the  op- 
posite portion  of  the  earth's  surface.  We  may  add  that,  in  consequence 
of  the  eccentricity  in  the  orbit  of  the  earth,  the  difference  of  duration  be- 
tween the  winter  and  summer  of  the  two  hemispheres  may  exceed  36 
days.* 

If  an  equality  of  seasons  between  the  two  halves  of  the  world  does  not 
at  present  exist,  it  will  not  fail  to  be  established  after  a  long  series  of  cen- 
turies by  means  of  a  slow  terrestrial  movement,  which  has  been  known 
by  the  name  o^  l\\e  precession  of  the  equinoxes.  Just  as  a  top  (if  we  may 
be  allowed  to  avail  ourselves  of  so  old  an  illustration)  turns  round  on  the 
ground  and  bends  over  successively  in  every  direction,  thus  describing 
with  its  axis  an  ideal  cone,  so  the  earth  revolves  in  space,  and  slowly 
sways  the  line  of  its  poles.  This  line,  which  is  always  sloped  at  an  angle 
*  Stone,  James  Croll,  CaiTick  Moore,  Lvell,  and  Le  Hon. 


22  THE  EARTH. 

of  66°  32'  to  the  plane  of  the  terrestrial  orbit,  turns  round  with  a  slight 
lateral  motion,  so  as  always  to  point  to  a  new  region  of  the  sky ;  if  it  were 
prolonged  indefinitely  it  would  describe  a  circle  amid  the  distant  stars. 
As  the  axis-  of  the  eftirth  is  constantly  changing  its  direction  in  this  way, 
the  plane  of  the  equator  must  vary  exactly  to  the  same  extent  in  its  po- 
sition as  regards  the  sun.  In  fact,  every  year  the  exact  moment  of  the 
March  equinox  anticipates  by  about  twenty  minutes  the  time  at  which  the 
corresponding  equinox  fell  in  the  year  preceding.  Each  revolution  of  the 
earth  round  the  sun  bi-ings  a  fresh  advance  of  twenty  minutes  in  the  de- 
termination of  the  equinox ;  and  as,  during  the  long  course  of  ages,  the 
axis  of  the  earth  does  not  intermit  in  this  swaying  motion,  the  time  must 
come,  after  a  period  of  12,900  years,  that  the  conditions  of  the  seasons 
will  be  altogether  changed.  The  hemisphere  which  hitherto  received  the 
larger  proportion  of  heat  will  receive  the  lesser  share,  and  that  half  of  the 
globe  which  had  endured  the  larger  number  of  wintry  days  will  now,  in  its 
turn,  enjoy  the  more  lengthened  period  of  summer.  Then,  after  a  second 
period  of  12,900  years,  during  which  the  relation  between  the  seasons  of 
the  two  hemispheres  is  being  gradually  modified,  the  axis  of  the  earth 
completes  its  round  of  swaying,  which  has  lasted  for  258  centuries,  and 
the  position  of  the  globe  in  respect  to  the  sun  being  nearly  the  same  as 
at  its  starting-point,  a  second  cycle  of  seasons  will  then  commence. 

We  might  call  this  period  the  eartKs  great  yem\  if,  at  the  end  of  it,  the 
earth  were  in  an  identicaLposition  to  that  which  is  occupied  at  the  com- 
mencement ;  but  this  is  not  the  case.  The  attraction  of  the  moon,  and 
■the  disturbances  caused  by  the  vicinity  of  certain  planets,  are  incessantly 
modifying  the  curve  described  in  the  starry  fields  of  space  by  the  earth's 
axis,  and  complicate  it  with  a  multitude  of  spirals,  the  various  periods  of 
which  do  not  coincide  with  the  great  period  of  the  swaying  of  the  axis. 
The  successive  undulations  form  a  continuous  system  of  interwoven  spi- 
rals.    "  It  is  a  manifestation  of  the  infinite."* 

But  even  this  is  not  all.  In  addition  to  all  the  motions  of  the  globe 
which  we  have  already  pointed  out — its  diurnal  rotation,  its  annual  rev- 
olution round  the  sun,  the  rhythmical  swaying  of  its  axis,  proved  by  the 
precession  of  the  equinoxes,  the  nutation  or  more  rapijd  swaying  which  is 
caused  by  the  attraction  of  the  moon — we  must  now  notice  the  enormous 
translatory  movement  which  is  dragging  it  through  endless  tracks  of 
space  in  the  train  of  the  sun.  Not  many  years  ago,  this  motion  was  en- 
tirely unknown  to  astronomers,  and  yet  it  is  going  on  with  inconceivable 
rapidity — a  rapidity  more  than  double  that  of  the  course  of  the  planet 
round  its  central  luminary.  In  one  second  of  time  the  earth  moves  about 
forty-four  miles  toward  the  point  of  the  heavens  where  we  find  the  con- 
stellation of  Hercules.  During  one  year  only,  she  travels  1382  millions 
of  miles  in  this  direction. f     Does  this  enormous  distance — which  light  it- 

*  Jean  Reynaud,  Terre  et  del,  Stone,  James  Croll,  Carrick  Moore,  Lyell,  and  Le  Hon. 
t  According  to  Bessel.      Vide  Humboldt's  Cosmos,  Faye's  transl.,  part  i.,  p.  102.     fetruve 
estimates  the  annual  movement  at  149  millions  of  miles  only. 


JMMEXSITY  OF  SPACE.  23 

self  would  take  two  hours  and  five  minutes  in  traversing — form  part  of 
an  ellipse  described  by  the  whole  planetary  system  round  some  centre  of 
attraction — a  centre  which  Maedler,  the  astronomer,  has  fancied  that  he 
has  discovered  in  Alcyone^  in  the  midst  of  the  Pleiades  ?  Or  is  it,  as  Ca- 
ms* supposes,  a  portion  of  an  orbit  which  has  for  its  focus  (like  the  curves 
of  multiple  stars)  a  centi-e  of  gravity  common  to  many  stars — nothing  but 
a  mathematical  point  everlastingly  changing  in  infinite  space?  We  can 
not  tell ;  but  certainly  this  movement  of  the  globe  we  live  on,  and  its  prog- 
ress through  the  unfathomable  depths  of  space,  must  give  us  an  idea  of 
the  immense  variety  of  the  motions  which  make  the  heavenly  bodies  gy- 
rate like  particles  of  dust  in  a  whirlwind.  Our  own  little  earth  itself  is 
carried  on  from  space  to  space,  and  never  closes  the  cycle  of  its  revolutions. 
Ever  since  the  time  when  its  particles  were  first  grouped  together,  it  has 
been  describing  in  space  the  infinite  spiral  of  its  ellipses,  and  thus  will  it  go 
on  turning  and  oscillating  in  ether  until  the  moment  when  it  will  exist  no 
tlonger  as  an  independent  planet.  Fer  the  earth,  too,  must  have  an  end ; 
like  every  other  body  in  the  universe,  it  comes  into  existence,  and  lives 
only  to  die  when  its  turn  comes.  Already  its  annual  motion  of  rotation 
is  diminishing  in  speed  ;f  certainly  this  slackening  of  pace  is  not  very  ob- 
servable, since  no  astronomer  from  Ilipparchus  to  Laplace  has  yet  exactly 
defined  it.  But,  unless  some  cosmical  force  acting  in  a  contrary  direction 
compensates  for  the  loss  of  speed  caused  by  the  friction  of  the  tides  against 
the  bed  and  the  shores  of  the  ocean,  the  impetus  of  our  planet  will  every 
century  diminish.  After  various  catastrophes  which  it  is  impossible  to 
foresee,  the  earth  will  eventually  completely  change  its  course  of  action, 
and  lose  its  independent  existence,  either  uniting  itself  with  other  plan- 
etary bodies,  or  breaking  up  into  fragments;  or  it  will  perhaps  terminate 
its  course  by  falling  like  a  mere  aerolite  upon  the  surface  of  the  sun. 
*  Naiur  und  Idee.  *  t  Meyer,  Joule,  Tyndall,  Adams,  Delaunay. 


24  THE  EARTH. 


CHAPTER  III. 

VARIOUS  OPINIONS  AS  TO  THE  FOUMATION  OF  THE  EARTH. — LAPLACE's  HY- 
POTHESIS ;  GRAVE  OBJECTIONS  RAISED  TO  IT. — THEORY  OF  A  CENTRAL 
fire;    OBJECTIONS  TO  IT. 

The  oriffin  of  the  earth  is  lost  in  the  dark  nisfht  of  our  iocnorance. 
From  the  observations  and  deductions  they  have  made,  none  of  our  sci- 
entific men  have  been  enabled  to  afford  us  any  exact  information  as  to 
the  way  in  which  our  planet  was  formed,  although  new  stars  are  constant- 
ly showing  themselves  in  the  infinity  of  space.  The  telescope  serves  only 
to  demonstrate  the  appearance  of  these  celestial  bodies,  and  fails  to  dis- 
close to  us  the  mode  of  their  formation.  On  one  occasion  only,  in  Decem- 
ber, 1845,  astronomers  had  the  good  fortune  to  witness  the  division  of  a 
comet — that  of  Biela ;  they  saw  it,  in  fact,  break  asunder  and  form  two 
nuclei  of  unequal  sizes,  which  traveled  on  into  space,  one  following  the 
other.  But  this  isolated  fact  will  not  justify  us  in  assuming  a  similar 
mode  of  formation  as  regards  all  the  heavenly  globes,  and  in  asserting  that 
the  stars  and  planets  are  produced  by  a  kind  of  bipartition  or  duplication. 
The  human  intellect  is  still  compelled  to  be  content  with  mere  hypothe- 
ses as  to  the  origin  of  our  own  and  other  planetary  globes.  All  cosmog- 
onies, from  the  legend  of  the  savage,  who  imagined  that  the  earth  sprang 
from  a  sneezing  fit  of  his  god,  down  to  the  theory  of  the  great  Buffon,  ac- 
cording to  which  the  planets  of  the  solar  system  are  the  fragments  launch- 
ed ftito  space  by  a  collision  between  a  comet  an*  the  sun,  the  vague  con- 
jectures of  the  ancients,  and  the  ideas  struck  out  by  modern  science — all 
alike  are  mere  suppositions  more  or  less  plausible  and  ingenious. 

The  hypothesis  which  at  the  present  day  still  receives  the  most  cre- 
dence is  that  which  was  first  proposed  by  Kant,  the  philosopher  (1755), 
and,  having  been  developed  by  Herschel,  was  taken  up  and  largely  des- 
canted on  by  Laplace  in  his  Exposition  du  Systhme  du  Monde.  So  great 
is  the  authority  of  this  illustrious  geometrician,  that  a  great  number  of 
persons  erroneously  look  upon  his  hypothesis  as  a  clearly  demonstrated 
scientific  fact.  It  is,  therefore,  hardly  permissible  to  omit  giving  some 
description  of  it,  even  in  the  briefest  sketch  of  the  primitive  history  of  the 
earth. 

Laplace  supposes,  in  the  first  place,  that  the  space  in  which  the  solar 
system  now  moves  was  filled  by  %.  gaseous  cosmical  matter  of  a  high  tem- 
perature, the  dilation  of  which  was  excessive,  compared  even  with  the 
most  rarefied  gases.  This  enormous  nebula  incessantly  radiated  heat 
around  it,  and  thus  supplied  a  portion  of  its  caloric  to  the  surrounding 
space ;  it  therefore  necessarily  condensed  gradually  round  a  central  point. 


THEORY  OF  LAPLACE.  25 

destined  one  day  to  become  our  sun.  The  particles  of  gaseous  matter, 
being  mutually  attracted  to  one  another,  were  not  only  subject  to  the  mo- 
tion of  condensation,  but  were  also  hurried  on  in  an  immense  circle  round 
the  axis  of  the  system.  The  loss  of  caloric  and  the  consequent  concentra- 
tion of  the  spheroidal  mass  had  the  effect  of  increasing  the  speed  of  rota- 
tion. At  the  same  time,  the  centrifugal  force  was  proportionately  in- 
creased, and,  under  the  influence  of  this  force,  the  atmospherical  mass,  be- 
coming flattened  at  the  two  poles,  assumed  gradually  the  form  of  a  disk. 
The  attraction  which  had  hitherto  retained  in  their  place  the  molecules 
of  the  circumference,  and  had  prevented  them  from  rushing  off  into  space, 
was  at  last  counterbalanced  by  the  centrifugal  force;  and  although  the 
larger  portion  of  the  gaseous  mass  continued  to  condense  around  the  cen- 
tral nucleus,  the  outer  zone,  acted  upon  at  the  same  time  by  two  opposite 
forces,  ceased  to  modify  its  distance  in  respect  to  the  axis  of  the  spheroid, 
and  assumed  the  form  of  a  circujar  revolving  ring. 

Other  rings  were  in  succession  separated  from  the  diminished  mass  in 
the  same  way,  and  continued  to  describe  their  rotatory  movement  round 
the  nucleus  or  sun.  According  to  the  hypothesis,  these  rings  were  the 
future  planets  of  the  solar  system.  The  lightest  were  necessarily  those 
which  were  the  most  remote  from  the  sun,  on  account  of  the  greater  tenu- 
ity of  the  incandescent  atmosphere  of  which  they  Avere  formed.  The  heav- 
iest were  those  which  were  subsequently  constituted  out  of  the  denser 
gaseous  layers  which  were  situated  nearer  to  the  centre  of  the  sun.  It  is, 
we  may  remark,  a  matter  of  fact  that  the  planets  farthest  removed  from 
the  central  focus,  such  as  Uranus  and  Neptune,  have  the  specific  gravity 
of  cork,  and  that  the  density  of  the  globes  increases  (although  not  follow- 
ing any  absolutely  regular  law)  as  they  are  in  closer  propinquity  to  the 
sun,  until  we  come  to  the  small  and  heavy  planets  in  the  interior  of  the 
system.  Besides,  the  planes  of  the  planetary  orbits  which  are  slightly  in- 
clined toward  one  another  would  point  out  the  position  of  the  sun's  equa- 
tor at  each  of  the  epochs  when  one  of  the  great  disruptions  took  place, 
which  gave  rise  to  a  fresh  planet. 

Although  constantly  getting  more  compressed,  owing  to  the  gradual 
loss  of  their  caloric,  these  annular  bodies  retained  their  shape  through  a 
more  or  less  prolonged  series  of  ages ;  but,  as  soon  as  one  of  these  seg- 
ments became  denser  than  the  rest  (in  consequence  of  some  astronomical 
perturbation),  it  exercised  an  ever-increasing  force  of  attraction,  and  at 
last,  breaking  up  the  zone  of  gaseous  matter,  gathered  the  matter  round 
itself  in  a  concentric  atmosphere.  Under  the  influence  of  the  laws  of  ro- 
tation, the  new  planet  soon  assumed  a  spheroidal  shape,  analogous  to  that 
of  the  body  from  which  it  had  sprung.  In  consequence  of  the  first  im- 
pulsive force  communicated  to  its  molecules,  its  motion  became  twofold ; 
it  continued  its  revolution  round  the  sun,  and  began  to  turn  round  on  its 
own  axis. 

The  forjnation  of  satellites  is  similarly  explained  by  the  gradual  shrink- 
ing  of  the  gaseous  mass  of  the  elementary  planets.     The  rings  separated 


26  THE  EARTH. 

from  the  equatorial  zone  of  these  bodies  would  be  likewise  condensed,  and, 
contracting  in  consequence  of  the  abstraction  of  their  caloric,  would  be- 
come so  many  moons.  The  pale  rings  of  Saturn  are  the  only  objects  in 
the  heavens  which  would  recall  the  ancient  shape  of  the  spheres  which 
the  condensation  of  the  sun,  and,  afterward,  that  of  the  planets  themselves, 
have  thrown  off  successively  into  space.  Once  upon  a  time,  according  to 
the  hypothesis,  they  were  nothing  but  an  equatorial  enlargement  of  the 
mother  planet ;  some  day  they  will  become  spherical  satellites,  like  the 
eight  moons  which  now  illumine  the  short  nights  of  Saturn. 

Thus,  according  to  Laplace's  ideas,  the  whole  planetary  system  formed, 
in  long  past  ages,  a  portion  of  the  sun.  This  luminary,  composed  solely 
of  gaseous  particles  much  lighter  than  hydrogen,  pervaded  with  its  enor- 
mous rotundity  the  whole  of  the  space  in  which  the  planets,  including 
Neptune,  are  now  describing  their  immense  orbits.  The  diameter  of  the 
solar  spheroid  must  then  have  been  6500  times  greater  than  it  now  is,  and 
its  bulk  must  have  surpassed  its  present  volume  by  more  than  860,000  mil- 
lions of  times.  In  the  same  way,  the  earth,  before  it  began  to  get  cool 
and  solidify,  w'ould  have  embraced  the  moon  within  its  limits,  and  its  di- 
ameter would  have  been  nearly  six  times  greater  than  that  of  the  planet 
Jupiter.  But,  unsubstantial  and  aerial  as  it  was,  our  earth  had  then  noth- 
ing but  a  cosmical  life  which  could  hardly  be  called  material ;  it  was  not 
until  it  became  more  solid  and  its  outer  crust  was  hardened  that  it  actu- 
ally commenced  its  real  existence. 

This  is,  no  doubt,  a  brilliant  hypothesis,  and  certainly  the  most  beauti- 
ful and  simple  that  any  astronomer  has  yet  put  forth.  It  accounts  better 
than  any  other  for  the  uniform  translatory  motion  of  the  planets  in  the 
direction  of  west  to  east;  it  also  apparently  agrees  in  a  remarkable  way 
with  certain  facts  in  the  subsequent  history  of  the  earth,  as  disclosed  to 
us  by  geology ;  finally,  the  marvelous  rings  which  surround  the  planet 
Saturn  seem  to  pi'oclaim  the  truth  of  the  theory  devised  by  Laplace. 
Thei'e  have  been  some  experiments  on  a  small  scale  which  apjieared  to  re- 
produce in  miniature  the  magnificent  spectacle  presented  in  the  primitive 
ages  by  the  origin  of  the  planets.  M.  Plateau,  a  Belgian  savant,  managed 
to  make  a  globe  of  oil  revolve  in  a  mixture  of  water  and  spirits  of  wine, 
which  was  of  exactly  the  same  specific  gravity  as  the  oil.  When  the  rev- 
olution of  the  little  globe  was  sufficiently  rapid,  it  was  noticed  to  flatten 
at  the  poles  and  to  swell  at  the  equator ;  after  a  time  it  threw  off  rings 
which  suddenly  assumed  the  shape  of  globules  actuated  by  a  rotatory  mo- 
tion of  their  own,  and  turning  round  the  central  globe.  Although  these 
planets  in  miniature  owed  their  existence  solely  to  the  expansion  of  the 
drop  of  oil  and  not  to  its  shrinking,  any  one  looking  at  it  might  well  fancy 
it  was  an  exact  representation  of  the  solar  system. 

But  Laplace  himself,  in  putting  forth  this  hypothesis,  says  that  he  does 
so  "  with  diffidence,"*  and  no  one  has  a  right  to  be  more  confident  than 
the  great  geometrician.  In  fact,  his  conjectures  do  not  account  for  the 
*  Exposition  du  Systhne  du  Monde,  p.  450. 


FORMATION  OF  PLANETS.  07 

presence  of  comets  which  gravitate  round  the  sun  in  determinate  orbits, 
although,  according  to  his  hypotliesis,  they  are  "  strangers  in  the  solar 
system;"*  they  also  fail  to  explain  the  elliptical  form  of  the  planetary  or- 
bits and  the  inclination  of  their  axes ;  finally,  they  appear  to  be  contra- 
dicted by  the  retrograde  motion  of  the  satellites  of  Uranus.  Some  of  the 
distant  nebula,  which  were  taken  by  astronomers  to  be  masses  of  uncon- 
densed  cosmical  matter,  possess  the  most  fantastic  forms,  which  would  be 
very  difficult  to  explain  by  means  of  the  new  hypothesis ;  some  of  the 
nehid(£,  too,  are  variable,  and  the  telescope  discloses  them  to  us  under  very 
different  aspects  in  succession,  '  Finally,  the  discovery  of  the  si)ectral 
analysis — an  eternal  glory  to  MM.  Kirchhoff  and  Bunsen — Avarrants  us  in 
believing  that  the  chemical  composition  of  the  sun  diflcrs  very  decidedly 
from  that  of  the  planets  forming  its  system ;  for  the  solar  body,  at  least 
in  its  external  layers,  does  not  contain  either  silex,  tin,  lead,  mercury,  sil- 
ver, or  gold.  We  must  therefore  confess  that  Laplace's  celebrated  and 
seductive  hypothesis  is  inadequate  to  account  for  all  the  phenomena  which 
have  been  observed.  The  human  intellect  ever  thirsts  for  certainty,  and 
readily  allows  itself  to  be  led  away  to  look  upon  mere  conjectures  as  ab- 
solute truths  ;  the  ability  of  fearlessly  doubting  is  not  the  meanest  attri- 
bute of  genuine  philosophy.  When  the  investigator  is  unable  to  discover 
the  truth,  let  him  dare  to  avow  his  ignorance,  and  rest  courageously  on 
the  threshold  of  the  unknown  world.  •  ** 

Another  hypothesis  connected  with  Laplace's  brilliant  astronomical  the- 
ory mu'st  be  added,  in  order  to  describe  the  formation  of  the  planetary 
crust.  When  the  gaseous  ring  became  condensed  into  a  globe,  it  would 
not  cease  to  contract,  owing  to  the  continued  radiation  of  its  caloric. 
The  whole  mass,  having  become  liquid  through  the  gradual  cooling  of  its 
molecules,  A^ould  be  changed  into  a  sea  of  lava  whirling  round  in  space ; 
but  this  state  was  only  one  of  transition.  After  an  indefinite  term  ofcen- 
tuiies,  the  loss  of  heat  was  sufficient  to  cause  the  formation  of  a  light  sco- 
ria like  a  thin  sheet  of  ice  over  the  sui-face  of  the  fiery  sea,  perhaps  just 
at  one  of  the  poles  where  nowadays  the  extreme  cold  produces  icebergs 
and  a  frost-bound  sea.  This  first  scoria  was  succeeded  by  a  second,  and 
then  by  others  ;  next  they  would  unit^into  continents  floating  on  the  sur- 
face of  the  lava,  and,  finally,  would  cover  tlie  whole  circumference  of  the 
planet  with  a  continuous  layer.  A  thin  but  solid  crust  would  then  have 
imprisoned  within  it  an  immense  burning  sea. 

This  crust  was  frequently  broken  through  by  the  lava  boiling  beneath 
it,  and  then,  by  means  of  the  solidification  of  the  sconcp,  was  again  united; 
the  cooling  process  would  tend  also  to  slowly  thicken  it.  After  a  lapse 
of  time,  which  must  have  been  immensely  protracted,  since  the  interval 
during  which  the  temperature  of  the  territorial  crust  would  be  lowered 
I'rom  2000°  to  200°  has  been  estimated,  at  the  very  least,  at  three  and  a 
half  millions  of  centuries,!  the  pellicle  at  last  became  firm,  and  the  enij)- 
tions  of  the  liquid  mass  within  ceased  to  be  a  general  phenomenon,  local- 

*  Erjijsition  dtt  Systente  tlu  Monde,  p.  475.  t  Ilclmholz. 


28  THE  EARTH. 

izing  themselves  at  those  points  where  the  firm  crust  was  the  thinnest. 
The  surrounding  atmosphere,  replete  with  vapore  and  various  substances 
maintained  by  the  extreme  heat  in  a  gaseous  state,  would  gradually  get 
lid  of  its  burden  ;  all  kinds  of  matter,  one  after  the  other,  would  become 
disengaged  from  the  luminous  and  burning  aerial  mass,  and  precipitate 
themselves  on  the  solid  crust  of  the  planet.  When  the  temperature  was 
lowered  sufficiently  to  enable  them  to  pass  from  a  gaseous  to  a  liquid 
state,  metals  and  other  substances  would  fall  down  in  a  fiery  rain  on  the 
terrestrial  lava.  Next,  the  steam,  confined  entirely  to  higher  regions  of 
the  gaseous  mass,  would  be  condensed  into  an  immense  layer  of  clouds, 
incessantly  furrowed  by  lightning.  Drops  of  water,  the  commencement 
of  the  atmospheric  ocean,  would  begin  to  fall  down  toward  the  ground, 
but  only  to  volatilize  on  their  way  and  again  ascend.  Finally  these  little 
drops  reached  the  surface  of  the  terrestrial  scoria,  the  temperature  of  the 
water  much  exceeding  100°,  owing  to  the  enormous  pressure  exercised  by 
the  heavy  air  of  these  ages ;  and  the  first  pool,  the  rudiment  of  a  great 
sea,  was  collected  in  some  fissure  of  the  lava.  This  pool  was  constantly 
increased  by  fresh  falls  of  Avater,  and  ultimately  surrounded  nearly  the 
whole  of  the  terrestrial  crust  with  a  liquid  covering ;  but,  at  the  same 
time,  it  brought  with  it  fresh  elements  for  the  constitution  of  future  con- 
tinents. The  numerous  substances  which  the  water  held  in  solution 
formed  various  combinations  with  the  metals  and  soils  of  its  bed  ;  the  cur- 
rents and  tempests  which  agitated  it  destroyed  its  shores  only  to  form 
new  ones ;  the  sediment  deposited  at  the  bottom  of  the  water  commenced 
the  series  of  rocks  and  strata  which  follow  one  another  above  the  primi- 
tive crust. 

Henceforward  the  igneous  planet  was  externally  clothed  with  a  triple 
covering,  solid,  liquid,  and  gaseous ;  it  might  therefore  becopje  the  theatre 
of  life.*  Vegetables  and  lowly  forms  of  animals  were  called  into  exist- 
ence in  the  water,  and  on  the  land  which  had  emerged  from  it ;  and,  final- 
ly, when  the  temperature  of  the  surface  of  the  globe  had  become  less  than 
50°,  allowing  albumen  to  liquefy  and  blood  to  flow  in  the  veins,  the  Fauna 
and  the  Flora  would  be  developed,  the  remains  of  which  are  found  in  the 
earliest  fossil  strata.  The  era  of  «haos  was  succeeded  by  that  of  vital 
harmony ;  but  in  the  immense  series  of  ages  we  are  dealing  with,  the  life 
which  appeared  on  the  refrigerated  planet  was  little  else  than  the  "  mould- 
iness  formed  in  a  day."f 

According  to  the  theory  generally  pro.pounded,  the  solid  crust  was  not 
very  completely  formed ;  it  is,  indeed,  much  thinner  than  the  layer  of  air 
surrounding  the  globe;  for,  following  the  common  estimate,  which,  how- 
ever, is  purely  hypothetical,  at  22  to  25,  or,  at  most,  50  miles  below  the 
surface  of  the  earth,  the  terrestrial  heat  would  be  sufficient  to  melt  gran- 
ite.J  Compared  to  the  diameter  of  the  earth,  which  is  about  250  times 
greater,  this  crust  is  nothing  more  than  a  thin  skin,  a  just  idea  of  which 

*  De  Jouvcncel,  Les  Commencements  du  Monde,  p.  37  seq.  t  Daubree. 

X  lliiinboldt's  Cosmos ;  Studer's  Physikalische  Geoijraphie,  vol.  ii.,  p.  37,  etc. 


MUTABILITY  OF  ITS  SURFACE.  29 

may  be  given  by  a  sheet  of  thin  cardboard  surrounding  a  liquid  sphere  a 
yard  in  diameter.  In  the  case  of  the  earth,  this  liquid  is  a  sea  of  lava  and 
molten  rocks,  having,  like  the  ocean  above  it,  its  currents,  its  tides,  and 
perhaps  its  storms.  The  geological  revolutions  of  the  globe  are  only  the 
reaction  of  the  subterranean  undulations  of  this  hidden  hell,  and  the  moun- 
tains of  porphyry,  greenstone,  and  ophite  are  but  the  congealed  ripples 
of  a  fiery  ocean.  Those  giants  on  the  sea-shore,  Etna,  the  Peak  of  Tene- 
riffe,  and  the  Mauna  lioa,  bear  witness  by  their  eruptions  and  their  lava- 
streams  to  the  tempests  which  are  raging  below  the  earth's  solid  crust. 

It  is,  in  fact,  very  probable  that  a  great  part  of  the  rocks  which  form 
the  outer  portion  of  our  planet,  especially  the  most  ancient  formations, 
existed  in  former  times  in  a  state  of  fusion  like  that  of  volcanic  lava.  As 
most  geologists  are  of  opinion,  granite  and  other  similar  rocks,  forming 
the  principal  building-blocks  in  the  architecture  of  continents,  existed  once 
in  a  soft  or  semi-soft  state ;  but  even  if  this  were  placed  beyond  a  ques- 
tion, it  could  not  confirm  tlie  hypothesis  relative  to  the  origin  of  our  plan- 
et, the  tenuity  of  its  crust,  and  the  existence  of  a  vast  central  fire. 

The  flattening  of  the  earth  at  the  two  poles  and  the  enlargement  at  the 
equator  have  been  alleged  as  unexceptional  evidence  that  the  globe  once 
existed  in  a  state  of  liquid  incandescence ;  in  fact,  any  liquid  sphere  turn- 
ing round  on  its  axis  would  necessarily  assume  this  shape  on  account  of 
the  unequal  speed  of  certain  points  of  its  bulk.  But  it  may  also  be  asked, 
with  Playfair,  whether  even  a  solid  globe  would  not  equally  tend  to  en- 
largement at  its  equator  if  it  urjceasingly  rotated  for  an  indefinite  series  of 
centuries  ?  For  no  existing  matter  is  altogether  inflexible,  and  under  the 
powerful  pressures  exercised  in  our  laboratories,  certainly  very  inferior  to 
the  influence  of  planetary  forces,  all  kinds  of  solid  bodies,  as  iron  and  steel, 
become  almost  as  yielding  as  liquids.*  Besides,  the  observations  and  cal- 
culations of  astronomers  and  geometricians  have  led  them  to  the  belief 
that  the  flattening  of  the  earth  at  the  two  poles  is  not  a  constant  quanti- 
ty, and  that,  therefore,  there  are  other  laws  diflerent  from  those  of  the  mo- 
tions of  rotation  and  revolution,  which  assist  in  modifying  the  form  of  our 
j)lanet.  Less  probably  at  the  northern  than  at  the  southern  pole,  the  ir- 
regularity of  the  sphere  appears  to  be  subject  to  periodical  changes  dur- 
ing the  course  of  ages,  and  is  also  complicated  with  several  other  inequal- 
ities, elevations,  or  depressions  which  the  oscillations  of  the  pendulum  and 
the  measurement  of  terrestrial  arcs  disclose  to  science.  One  of  the  grav- 
est subjects  of  study  presented  by  physical  geography  is  precisely  this 
mutability  of  the  surface  of  the  earth,  which,  at  various  points  of  the  globe, 
rises  or  sinks  with  extreme  slowness.  Although  we  are  still  ignorant  of 
the  certain  cause  of  these  risings  and  depression^  there  is  at  least  no  rea- 
son to  believe  that  they  are  due  to  the  centrifugal  force  developed  by  the 
rotation  of  the  earth.f 

Neither  must  it  be  forgotten  that,  under  the  hypothesis  admitted  by 

*  Erperiences  du  Conservatoire  dea  Arts  et  Metiers,  18fi4. 
t  Vide  the  chapter  as  to  "  UphenviUs  and  Depressions." 


30  TUE  EARTH. 

those  who  assume  the  existence  of  a  central  fire,  our  planet  is  to  be  con- 
sidered as  actually  a  liquid  mass,  as  the  external  orust  is  in  comparison 
but  a  thin  skin.  Under  these  conditions,  it  would  be  difficult  to  believe 
that  this  great  ocean  of  lava  is  not,  like  the  watery  ocean,  agitated  by  the 
alternating  motion  of  tides,  and  that  it  does  not  move  twice  every  day 
the  raft,  as  it  were,  which  is  floating  on  its  surface.  It  is  difficult  to  un- 
derstand how  it  is  that  the  earth  is  not  much  more  depressed  at  the  poles 
than  it  now  is,  and  has  not  been  transformed  into  a  real  disk.  This  flat- 
tening of  the  poles  is  not  more  considerable  than  the  mere  superficial  in- 
equalities in  the  equatorial  zone  between  the  summits  of  the  Himalayas 
and  the  abysses  of  the  Indian  Ocean.  M.  Liais  attributes  the  slight  flat- 
tening of  the  two  poles  to  the  erosion  which  the  water  and  ice  in  those 
parts,  irresistibly  drawn  as  they  are  toward  the  equator,  incessantly  cause, 
year  after  year  and  century  after  century,  by  the  enormous  quantity  of 
debris  torn  away  from  the  surface  of  the  soil,  which  they  bear  with  them. 
Lastly,  M.  Bisclioff",  having  ascertained  from  the  principal  soundings  that 
have  been  taken  that  the  sea  increases  in  depth  from  the  poles  in  the  di- 
rection of  the  equator,  goes  so  far  as, to  deny  the  ellipsoidal  form  as  re- 
gards the  bed  of  the  sea,  that  is,  over  the  greater  portion  of  the  planetary 
surface. 

The  principal  argument  of  those- who  look  upon  the  existence  of  a  cen- 
tral fire  as  a  demonstrated  fact  is  that,  in  the  external  strata  of  the  earth, 
so  far  as  they  have  been  explored  by  miners,  the  heat  keeps  on  increasing 
in  proportion  to  the  depth  of  the  excavation.  In  descending  the  shaft  of 
a  mine  we  invariably  pass  through  zones  of  increasing  temperature;  only 
the  rate  of  increase  varies  in  difierent  parts  of  the  earth,  and  according  to 
the  strata  through  which  the  shaft  is  sunk.  The  heat  increases  more  rap- 
idly in  schist  than  in  granite,  and  in  metallic  veins  more  even  than  in 
.schist;  in  lodes  of  copper  more  than  in  those  of  tin,  and  in  beds  of  coal 
I  more  than  in  metallic  veins.*  In  the  Artesian  well  at  Xeuflen,  in  Wtir- 
/  tembcrg,  the  temperature  increases  one  degree  Fahrenheit  for  every  19 
J  feet.  In  the  mines  of  Monte  Masi,  in  Tuscany,  near  the  boracic  springs, 
th(J  increase  of  heat  is  one  degree  for  every  24  feet.  Near  Jakutzk,  in  Si- 
beria, the  heat  of  the  earth  increases  one  degree  for  every  29  feet  of  depth.f 
Almost  every  where,  however,  the  progression  is  less  rapid ;  and  the  mean 
depth  which  in  this  great  stratiform  thermometer  corresponds  to  a  degree 
of  heat  is  from  45  to  54  feet.J  In  the  mines  of  Saxe,  the  increase  of  heat, 
according  to  Reich,  is  one  degree  for  every  76  feet. 

Still,  the  earth  has  not  yet  been  explored  to  any  very  great  depth.  The 
most  remarkable  excavations  which  have  yet  been  made  are  those  of  Kut- 
tenberg,  in  Bohemia,  and  one  of  the  mines  of  Guanajuato,  in  Mexico ;  even 
these  have  scarcely  attained  a  depth  of  1100  yards,  not  more  than  a  six  or 

*  Foxe,  Gilbert,  Reicli  von  Dechen,  quoted  by  Bischoffin  his  Warmelehre,  p.  169-171. 
t  CoUegno,  Geoloffin,  p.  2G. 

t  BisclioflF,  Warmelehre,  p.  2'A.  The  learned  German  professor  endeavors  even  to  trace 
out  in  v.irious  countries  chlhonisotliermes,  or  cunes  of  equal  subtenanean  heat. 


ITS  INTERNAL  CONDITION.  31 

seven  thousandth  part  of  the  earth's  radius.  It  would,  therefore,  be  some- 
thing more  than  imprudence  were  we  to  attempt  to  form  a  judgment  as 
to  the  whole  interior  of  the  globe  by  the  temperature  of  the  external  strata, 
and  to  affirm  that  the  heat,  increasing  according  to  some  constant  propor- 
tion from  the  surface  of  the  soil  to  the  centre  of  the  earth,  would  attain 
to  a  temperature  of  200,000° — a  heat  far  beyond  the  power  of  man's  im- 
agination to  conceive.  In  the  same  way  we  should  have  to  conclude,  from 
the  gradual  cooling  of  the  high  aerial  layers,  that  the  decrease  of  heat 
would  continue  up  to  the  midst  of  celestial  space,  and  that  at  miles  above 
the  earth  the  cold  is  equal  to  6000°  below  zero.  The  supei^ficial  portion 
of  the  globe  is  traversed  incessantly  by  magjnetic  currents,  taking  their 
course  from  pole  to  pole,  and  in  this  portion  all  those  phenomena  of  plan- 
etary vitality  take  place  which  are  constantly  modifying  the  elevation 
and  form  of  continents ;  this  surface,  therefore,  must  doubtless  exist  under 
altogether  special  conditions  as  regards  the  development  of  heat.  The 
thiimcss  of  the  earth's  crust  is  therefore  any  thing  but  proved  by  the  grad- 
ual increase  of  temperature  in  the  shafts  of  mines  and  other  excavations. 

M.  Cordier,  being  struck  by  all  the  objections  which  presented  them- 
selves to  his  mind  as  to  the  thinness  of  the  terrestrial  crust,  has  admitted 
that  this  covering  could  not  be  stable  without  having  at  least  from  75  to 
175  miles  of  thickness. 

Quite  lately,  Mr.  Hopkins  having  subjected  to  the  calculations  of  the 
higher  mathematics  all  the  elements  furnished  by  the  phenomena  of  the 
terrestrial  precession  and  nutation,  has  arrived  at  the  following  result. 
He  has  proved  that,  either  with  or  without  a  central  fire,  our  planet  would 
be  actuated  by  periodical  movements  of  a  totally  different  character,  if 
the  solid  portion  of  its  crust  had  not  a  thickness  of  800  to  1000  miles — 
that  is  to  say,  about  a  quarter  or  a  fifth  of  ^e  earth's  radius.*  MM. 
Thomson,  Emmanuel  Liais,  and  other  savants,  taking  up  and  discussing 
all  these  investigations,  have  endeavored  to  prove  that,  looking  at  the  va- 
rious astronomical  phenomena,  the  interior  solidity  of  our  planet  is  an  in- 
controvertible fact.f  Nevertheless,  the  recent  experiments  of  M.Delaunay 
on  glass  globes  filled  with  water  render  it  very  probable  that  even  if  the 
earth  contained  a  mass  of  molten  matter,  this  mass  would  rotate,  together 
with  the  crust,  as  if  it  were  a  solid  body,  and  would  adopt  a  similar  course 
as  regards  the  attractiofis  of  the  sun  and  moon.  We  are  not,  therefore, 
warranted  as  yet  in  pronouncing  any  decisive  opinion.  The  hypothesis 
which  seems,  both  to  Mr.  Hopkins  and  also  to  Sartorius  von  Waltershau- 
sen,  the  historian  of  Etna,  to  harmonize  best  with  the  volcanic  phenome- 
na,J  is,  that  there  is  no  actual  central  fire,  but  only  internal  seas  of  red- 
hot  molten  matter  scattered  about  in  various  paj-ts  of  the  inside  of  our 
])lanet,  situated  not  far  from  the  surface  of  the  earth,  and  separated  from 
one  another  by  masses  of  solid  strata. 

*  Philosophical  Transactions,  1839,  1840, 1842.  ^ 

t  L'Espace  Celeste  et  la  Nature  Tropicale. 
X  Vide  the  chapter  on  "Volcanoes." 


32  THE  EARTH. 


CHAPTER  IV. 

GEOLOGICAL  STRATA. CONGLOMERATES. SANDSTONES.  —  CLAYS.  —  LIME- 
STONES.  FOSSILIFEROUS  BEDS. — SEQUENCE  OF  ORGANIC  BEINGS. — GEN- 
ERAL CLASSIFICATION   OF    STRATA. DURATION   OF   GEOLOGICAL  PERIODS. 

The  most  ancient  positive  evidence  relative  to  the  geological  history 
of  the  earth  is  afforded  by  the  first  sedimentary  layers  which  can  be  cer- 
tainly recognized  as  having  been  deposited  by  water  on  some  primitive 
ocean-bed.  Below  the  supei-ficial  strata  of  more  modern  origin  we  find 
others  belonging  to  a  remoter  epoch,  and  then  others  of  a  still  antecedent 
formation ;  thus  we  proceed  from  stratum  to  sti-atum  down  to  the  naked 
skeleton  of  the  earth,  or,  at  all  events,  to  those  rocks  which  the  pressure 
of  the  masses  above  and  the  planetary  heat  have  gradually  transformed 
during  the  long  duration  of  ages,  so  as  to  render  their  stratification  uncer- 
tain. These  superimposed  beds,  which  have  often  been  compared  to  the 
pages  of  a  book,  furnish  the  date  of  their  seniority  by  the  order  of  their 
succession ;  certainly  we  can  not  say  how  many  hundreds  or  thousands 
of  centuries  have  elapsed  during  the  formation  of  each  sedimentary  bed, 
but  we  may  at  least  learn  the  relative  ages  of  the  series  of  rocks. 

Wherever  these  strata  have  not  been  disturbed  since  their  first  origin, 
they  still  lie  in  parallel  and  almost  horizontal  layers  as  at  the  bottom  of 
the  sea  which  deposited  them ;  in  this  case  nothing  is  more  easy  than  to 
class  them  in  their  orde^of  seniority.  The  geologist  Avho  descends  the 
shaft  of  a  jnine  sunk  vertically  into  the  earth  may,  as  it  were,  traverse  tl.e 
whole  series  of  periods  down  to  the  primitive  ages ;  in  a  few  minutes  he 
may  see  a  kind  of  abstract  of  the  geological  history  of  the  earth.  In  the 
same  way,  in  places  where  the  agency  of  various  meteoric  phenomena  and 
the  forces  at  work  in  the  interior  of  the  earth  have  cut  through  any  por- 
tion of  the  upper  strata,  causing  steep  escarpments,  which  show,  as  on  an 
immense  wall,  the  sui^erimposed  beds,  the  order  of  succession  of  the  differ- 
ent rocks  can  not  be  the  subject  of  doubt.*  On*  the  other  hand,  in  coun- 
tries where  the  strata  have  been  upheaved  at  various  angles,  being  either 
distorted,  displaced,  or  sometimes  even  completely  turned  upside  down — 
where  rocks  springing  from  the  earth  in  a  liquid  state,  such  as  porphyry 
and  lava,  have  forced  their  way  between  the  beds,  the  investigations  of 
the  geologist  become  very  difficult,  and  much  patience  and  sagacity  are 
required  to  attain  any  result.  Finally,  the  greatest  and  most  difficult 
problem  is  to  establish  the  harmony  in  age  and  formation  between  various 

*  The  opposite  profile  of  the  "Pyramid  Mountain,"  taken  from  vol.  iii.  of  the  Pacific  Rail- 
road Report,  has  been  revised  by  M.  Marcou,  the  geologist,  who  was  the  first  to  bring  under 
notice  the  existence  of  this  remarkable  mountain  (Fig.  3). 


THE  CHUST  OF  THE  EARTH. 


33 


rocks  separated  by  valleys,  large  plains,  or  even  by  the  ocean.  Thus 
doubt  still  exists  as  to  a  great  number  of  details,  and  variance  on  these 
points  often  arises  among  geologists.  Nevertheless,  whether  deciphered 
or  not,  these  strata,  with  the  various  indications  which  are  presented  by 
their  minerals  and  fossils,  are  the  only  authentic  annals  of  our  planet. 
They  are  the  hieroglyphics,  still  in  part  mysterious,  which  relate  to  us  in 
their  magnificent  characters  the  history  of  the  world  itself. 


Fig.  3.  The  Pyramid  Muuiitaiii. 

These  innumerable  strata,  so  diverse  in  their  position,  inclination,  and 
thickness,  are  analogous  to  the  beds  of  the  same  nature  that  we  notice  in- 
cessantly in  the  course  of  formation.  Mountains  furrowed  out  by  torrents 
and  cliffs,  sapped  by  the  wave^,  supply  either  to  rivers  or  direct  to  the  sea 
masses  of  f/e6m,  which,  spread  out  into  shingle-strands  or  beds  of  pebbles, 
are  gradually  changed  into  solid  conglomerates.  The  crystalline  rocks, 
pulverized  by  atmospheric  agencies  and  the  friction  of  river  and  sea-water, 
become  submarine  sand-banks,  which  sooner  or  later  are  converted,  under 
the  pressure  of  the  superincumbent  masses,  into  rocks  of  sandstone.  The 
tranquil  waters  of  slow-flowing  streams  and  rivers,  which  neither  carry 
pebbles  along  with  them  in  their  course,  nor  are  charged  with  sandy  mat- 
ter, are  still  loaded  with  small  particles  of  ooze  and  earth,  which  they  de- 
posit on  their  banks  and  in  the  bed  of  the  sea,  forming  those  beds  of  clay 
which  also  ultimately  constitute  important  geological  formations.  On  the 
banks  of  the  Mississippi  there  are  enormous  argillaceous  beds  which  the 
water  of  the  river  has  left  behind  it;  these  are  apparently  no  less  firm 
than  Che  rocks  which  have  for  centuries  met  the  assaults  of  the  waves  and 

C 


34  THE  EARTH. 

Storms.  In  certain  lakes  in  Mexico,  and  especially  round  the  reefs  of 
Florida,  oolites  like  those  of  the  Jura  are  daily  being  formed  before  our 
eyes.  Finally,  in  the  shallows  of  the  sea,  fresh  beds  are  being  formed,  as 
of  limestone  at  Guadaloupe,  or  of  drift  brought  by  the  sea,  as  upon  the 
great  bank  of  Newfoundland.  In  the  same  way,  coral  insects,  madrepores, 
and  other  marine  animals  are  incessantly  at  work  in  building  up  new  beds 
similar  to  those  of  the  ancient  geological  periods.  The  formations  caused 
in  days  of  yore  by  the  movement  of  the  water,  and  the  pei-petual  activity 
of  teeming  marine  life,  all  are  still  in  progress,  and  disclose  to  us  in  what 
way  the  earth's  surface  was  modified  during  a  long  series  of  ages. 

Although  all  strata  may  be  classed  in  a  general  way  in  one  of  the  five 
great  series  —  conglomerates,  sandstone,  clays,  gravels,  and  limestone — 
nevertheless,  in  their  various  shades  of  distinction,  their  relative  positions, 
and  the  minerals  which  they  contain,  they  present  indications  which  allow 
of  their  being  classed  according  to  their  respective  ages.  But  the  organic 
remains,  animal  or  vegetable,  which  are  contained  in  the  greater  part  of 
these  various  formations,  are  the  means  which  afford  us  the  pi-incipal  data 
for  ascertaining,  often  with  certainty,  the  order  of  succession  of  the  vari- 
ous layers.  Natural  history  alone  enables  us  to  decipher  clearly  these 
pages  in  the  earth's  history. 

That  organic  remains  are  preserved  in  the  ground  in  an  altogether  ex- 
ceptional way  is  a  fact  which  naturalists  have  innumerable  opportunities 
of  satisfying  themselves  of,  in  the  study  of  the  plants  and  animals  of  our 
own  time.  Dead  animals  are  soon  devoured  by  beasts  of  prey  and  in- 
sects ;  water,  wind,  and  sun  ere  long  dissolve  all  that  remains  of  flesh  or 
ligaments ;  the  skeleton  itself  is  finally  reduced  to  dust.  The  infinite  le- 
gions of  inferior  creatures  which  have  no  solid  bones  disappear  in  myriads 
without  leaving  the  slightest  trace  behind  them,  and  the  piled-up  masses 
of  their  remains  are  soon  changed  into  humus  and  gas.  Forest  trees  and 
herbaceous  plants  disappear  like  animals,  and  furnish  nutriment  to  other 
existences.  Scarcely  have  they  perished  ere  the  former  organisms  aid  in 
forming  new  ones — death  is  the  constant  food  of  life.  The  remains  of  ex- 
tinct vitality  can  only  be  preserved  for  future  ages  by  being  suddenly  re- 
moved from  the  tooth  of  the  animal  and  the  action  of  the  elements.  Thus 
organic  remains  which  are  clothed  by  petrifying  springs  with  a  covering 
of  lime,  and  the  trunks  of  trees  which  are  surrounded  by  sheets  of  lava, 
become  as  indestructible  as  stone  itself  Animals  caught  in  the  ice,  over- 
whelmed by  falling  earth,  or  which  have  died  in  some  deep  and  inaccessi- 
ble cave,  may  be  kept  for  centuries  in  a  condition  of  perfect  preservation, 
and  may  pass  into  a  fossil  state.  But  although  it  is  comparatively  very 
rare  that  a  terrestrial  being  is  preserved  for  future  ages  either  whole  or 
only  in  fragments,  the  case  is  not  the  same  as  regards  marine  creatures, 
which  are  ingulfed  immediately  after  death  or  even  during  their  life  in 
the  sand  or  mud  which  is  brought  by  the  waves.  Thus,  in  the  sediments 
of  fonner  marine  beds  and  deltas,  we  find  multitudes  of  fossil  animals  of 
which  even  the  most  delicate  parts  are  wonderfully  preserved;  we  see 


RARITY  OF  ORGANIC  REMAINS.  35 

this  in  the  beautiful  specimens  in  our  museums  brought  from  the  beds  of 
Solenhofen,  Monte  Bolca,  Grignon,  and  Montmartre, 

Besides  all  this,  on  those  shores  where  the  tides  are  considerable — in 
the  Severn,  St.  Michael,  and  the  Bay  of  Fundy — the  ooze  brought  by  the 
waves  has  frequently  covered  the  footmarks  of  vertebrate  animals,  the 
tracks  traced  out  by  crustacese,  worms,  and  molluscs,  and  also  the  marks 
made  by  the  rain-drops,  and  by  strong  squalls  of  wind.  This  mud,  grad- 
ually hardening,  may  at  last  become  beds  of  schist,  sandstone,  and  clay ; 
and  thus,  after  millions  of  years,  similar  imprints  of  an  instant  are  found 
graven  on  the  rocks,  deeper  and  more  legible  to  the  eye  of  the  geologist 
than  the  ambitious  inscriptions  of  the  kings  of  the  world.  But  these 
magnificent  evidences  of  the  past  are  only  common  as  regards  marine 
beings ;  there  is  very  little  chance  of  fossilization  for  any  thing  which 
lives  on  the  emerged  strata,  in  the  air,  or  in  fresh  water. 

As  the  preservation  of  organic  forms,  or  of  impressions  made  by  them, 
depends  on  exceptional  conditions,  a  great  number  of  strata  are  partly 
destitute  of  fossils,  whilst  immediately  above  and  below  them  geologists 
are  able  to  discover  multitudes  of  the  remains  of  the  ancient  inhabitants 
of  the  globe.  Thus  the  deficiency  of  evidence  in  a  stratum  absolutely  de- 
cides nothing  against  the  existence  of  life  in  any  particular  period  of  the 
planetary  history.  The  negative  conclusions  as  to  life  which  many  savants 
have  desired  to  deduce  from  the  absence  of  fossils  in  certain  beds  are  not 
based  on  any  sure  ground.  Besides,  the  exploration  of  the  globe  is  scarce- 
ly commenced,  and  a  number  of  beds  in  which  no  relics  had  previously 
been  discovered  have  since  presented  to  science  plenty  of  geological  treas- 
ures ;  in  addition  to  which,  we  must  not  forget  that  there  are  great  unex- 
plored tracts  at  the  bottom  of  the  sea,  as  well  as  on  terra-firma. 

The  appearance  and  disappearance  of  fossil  species  are  not  in  perfect 
harmony  with  the  succession  of  rocks,  and  consequently  the  idea  is  not 
warranted  which  connects  some  kind  of  cataclysm  with  the  end  of  each 
geographical  period.  A  continuity  of  life  has  linked  together  all  the  for- 
mations, from  the  first  organized  beings  which  made  their  appearance  on 
the  earth  down  to  the  countless  multitudes  which  now  inhabit  it.  One 
species  would  perhaps  live  but  for  a  very  short  period  of  the  planetary 
history ;  another  species  would  make  its  appearance  in  a  certain  bed ;  at 
first  it  would  be  rare,  and  as  if  trying  to  force  its  way  into  life ;  then  it 
would  multiply  from  stratum  to  stratum,  and  afterward  would  either 
gradually  become  extinct,  getting  less  and  less  through  a  whole  series  of 
ages,  or  suddenly  disappear.  Other  generic  forms  appear  to  have  passed 
through  every  epoch,  and  representations  of  them  exist  after  millions  of 
centuries.  The  duration  of  a  species  does  not  depend  either  on  the  various 
revolutions  which  have  modified  the  bed,  or  on  any  other  external  cause, 
but  on  its  own  special  vitality.  In  a  general  way,  the  duration  of  the 
existence  of  any  series  of  beings  is  in  proportion  to  the  more  or  less  rudi- 
mentary character  of  its  organization.  The  inferior  vertebrate  creatures 
have  all  pervaded  a  more  extended  geological  cycle  than  that  in  which 


36  THE  EARTH. 

superior  vertebrate  animals  are  found ;  Foraminifera  have  run  through  a 
much  longer  series  of  ages  than  molluscs ;  the  latter,  as  well  as  fishes  and 
reptiles,  have  a  much  longer  existence  as  species  than  Mammalia.  Finally, 
the  great  mammals  of  the  Tertiary  epoch  enjoyed  but  a  comparatively 
short  term  of  existence ;  they  were  unable  to  resist  the  variable  influences 
of  climate  so  well  as  the  inferior  animals.  The  higher  an  organism  is 
raised  in  the  scale  of  being,  the  narrower  are  the  limits  between  which  it 
is  confined ;  all  that  it  gains  in  rank,  it  loses,  if  not  in  number,  at  least  in 
duration  of  existence  as  a  species.* 

In  what  order  did  the  various  species  of  animated  beings  follow  one 
another  on  the  earth  ?  Not  long  ago,  geologists  put  forward  a  very  sim- 
ple system  on  this  point.  According  to  their  preconceived  ideas,  the  infe- 
rior animals,  including  the  class  of  Crustacea,  were  the  exclusive  inhab- 
itants of  the  surface  of  the  planet  during  the  formation  of  the  most  ancient 
geological  beds.  Fishes  made  their  first  appearance  during  the  period  of 
the  Old  Red  Sandstone ;  reptiles  came  into  existence  in  those  hollows  and 
marshy  shallows  where  the  vegetable  remains  were  accumulating,  which 
subsequently  became  transformed  into  coal.  Birds,  properly  so  called, 
first  took  flight  at  the  Cretaceous  epoch ;  next  came  quadrupeds  in  reg- 
ular order,  from  the  inferior  species  to  the  very  highest.  The  ape  did  not 
form  one  of  their  number  until  immediately  before  the  appearance  of  man, 
and  the  latter  was  created  after  all  the  other  animals,  as  if  to  sum  up  in 
his  person  all  the  long  catalogue  of  anterior  life. 

The  discoveries  made  during  the  last  few  years  by  indefatigable  inves- 
tigators, such  as  Lyell,  Forbes,  Barrande,  O^jven,  Leidy,  Emmons,  and  Wag- 
ner, have  singularly  disturbed  the  serial  order  of  species  which  had  been 
previously  established.  Ferns,  Lycopodiaceoe,  and  Calamitece,  which  were 
thought  to  be  the  only  families  represented  in  the  Coal  Measures,  have 
been  added  to  by  many  other  species,  belonging  to  other  families,  and 
even  to  the  Dicotyledonous  order.  More  than  thirty  species  of  reptiles 
have  been  discovered  in  those  very  strata  in  which,  according  to  the  views 
of  many  geologists,  not  one  ought  to  have  been  found.  Mammals  of  the 
marsupial  order  have  been  discovered  in  the  Rhaetic  beds  of  Somerset,  and 
even  in  the  Trias,  at  the  termination  of  rocks  of  Palaeozoic  formation. 
Apes,  at  least  as  highly  organized  as  those  of  our  day,  lived  during  the 
period  of  the  Upper  Miocene,  and  man  was  the  contemporary  of  the.  cave- 
bear,  of  the  mammoth,  the  woolly  rhinoceros,  and  other  great  animals  now 
extinct.  No  year  passes  in  which  geologists  fail  to  discover  in  the  terres- 
trial strata  new  animal  and  vegetable  forms,  which  transfer  our  geological 
,  horizon  to  periods  still  more  and  more  remote.  The  facts  which  prove 
the  existence  of  organisms  of  a  superior  class  in  the  more  ancient  terres- 
trial beds  have  become  so  numerous  that  certain  palaeontologists  have 
ventured  to  doubt  the  progressive  development  of  the  animal  and  vege- 
table series  during  the  various  geological  periods.     In  their  view,  it  is  in 

*  Collomb,  Bibl.  de  Geneve,  Archives  Scientijiques,  Aug.,  1866.  Wallich,  North  Atlantic 
Sea-bed,  p.  95.     Lyell,  Darwin,  Gaudrj-,  Carpenter,  etc. 


GEOLOGICAL  MAP   OF   ENGLAND 


PL.ni 


Jioti«m  £ecLt 
Tertiary    do 
Uretacembs  do 
Jiirrussie      (to 
TfinK  and  Per7fumt  do- 


Etawii    by  A  Vinllcmin   after      Raonsay. 

HAHPER  &.  BROTHERS.  l\YM  YORK 


T.ng^   by  Irhar<J 


EARLIEST  LIVING  BEmOS.  37 

each  group  of  species,  and  not  among  animated  beings  as  a  body,  that  we 
must  seek  for  the  order  of  development.*  If,  however,  we  embrace  in  one 
glance  the  whole  body  of  beings,  instead  of  considering  only  the  earliest 
and  the  latest  ones,  we  are  bound  to  recognize  that  there  has  certainly 
been  a  progress  in  the  organic  series.  In  its  period  of  greatest  exuberance 
vegetable  life  preceded  animal  life ;  in  the  primitive  ages  plants  destitute 
of  flowers  were  much  more  numerous  than  the  flowering  species ;  Crusta- 
ceae,  molluscs,  and  other  lower  animals  had  their  golden  age  before  fishes 
and  reptiles,  and  the  latter  appear  to  have  been  the  lords  of  the  earth  be- 
fore mammals  appeared  on  the  scene.  Even  among  the  latter  it  seems 
very  probable  that  progress  was  the  rule,  for  most  of  the  animals  in  the 
Oolitic  beds  are  marsupials,  and  it  was  not  until  the  Tertiary  age  that  the 
larger  mammals  attained  their  more  complete  development.!  Agassiz 
thinks  that  the  types  of  the  ancient  epochs  represent  the  embryos  of  now 
existing  beings,  so  that  pala;ontology  teaches  us  of  the  infancy  of  all  those 
forms  of  existence  which  are  now  found  in  a  fully  developed  state. 

Be  this  as  it  may,  the  fossiliferous  geological  beds,  from  the  most  an- 
cient to  the  most  recent,  are  all  linked  one  to  another  by  species  common 
to  two  or  more  of  their  number.  Thanks  to  the  succession  of  their  differ- 
ent species,  and  in  spite  of  the  numerous  variations  in  the  names  used  by 
them,  geologists  are  now  pretty  well  agreed  as  to  the  general  classifica- 
tion of  the  rocks  over  the  whole  surface  of  the  earth.  The  most  ancient 
formations,  or  the  Palaeozoic,  resting  on  the  granite  or  other  rocks  of  a 
similar  nature,  and  comprising  the  Taconic,  the  Cambrian,  the  Silurian, 
and  the  Old  Red  Sandstone  groups,  are  the  earliest  strata  in  which  we  find 
any  remains  of  organic  beings ;  in  them, "  in  the  dawn  of  vitality,"  sprang 
into  life  Eozoon  Canadense  (if,  indeed,  it  exists  at  all,  except  in  the  imag- 
ination of  certain  geologists)  and  the  Braintree  trilobite  [Paradoxides 


Ilg.  1.  Paradoxides  Harlani. 


Harlani),  which  disputes  with  the  Eozoon  the  honor  of  having  been  the 
"  Adam"  of  the  terrestrial  Fauna.  This  period  of  the  earth's  history,  itself 
the  successor  of  periods  all  unknown,  was  followed  by  the  age  of  Carbon- 

*  Lyell,  Supplement  to  Manual,  p.  35.     [Sir  Charles  Lyell  hns  since  (in  the  tenth  edition 
of  his  "  Princij)les  of  Geology,"  1 8(;8)  fully  accepted  the  Darwinian  Theory.] 
t  Bronn,  Albert  Gaudry,  Owen,  Hermann  von  Meyer,  Lartet, 


38  THE  EARTH 

iferous  beds,  including  the  Mountain  limestone  rocks  and  the  various  lay- 
ers of  the  Coal  formations.  Above  lie  the  beds  of  the  New  Red  Sand- 
stone. Next  in  the  geological  series  come  the  numerous  Jurassic  and 
Cretaceous  stages,  known  as  a  whole  under  the  name  of  Secondary  rocks. 
The  last  period  preceding  the  present  epoch  witnessed  the  deposit  of  the 
Eocene,  Miocene,  and  Pliocene  rocks,  and  is  connected  by  the  Quaternary 
strata  to  the  formations  which  are  now  being  constituted  before  our  eyes. 
Finally,  the  incandescent  lavas,  trachytes,  dolerites,  and  basalts  which  have 
made  their  way  from  below  and  have  traversed  the  stratigraphical  series, 
constitute  a  sixth  class  of  rocks. 

Although  the  general  groups  are  the  same  in  the  two  hemispheres,  the 
numerous  geological  strata  in  the  various  countries  of  the  world  differ 
singularly  in  their  fossils  and  other  characteristics.  Nowhere  do  they 
present  absolute  harmony,  and  it  is  therefore  very  difficult  to  class  them 
certainly  in  their  respective  order  of  succession.  In  former  times,  as  now, 
animals  and  plants  differed  according  to  climates,  and  therefore  the  strata 
which  received  all  these  debris^  received  each  of  them  its  own  special  geo- 
logical character.  In  the  varieties  which  the  fossil  Fauna  and  Flora  pre- 
sent to  us,  how  much  is  owing  to  a  difference  of  epoch,  and  how  much  to 
a  diversity  of  climate?  The  solution  of  this  problem  is  one  of  the  great 
tasks  of  science  ?* 

*  Marcon,  Roches  du  Jura,  p.  240. 


MODIFICA  TION  OF  THE  EAJtTH'S  SURFA  CE.  39 


CHAPTER  V. 

INCESSANT  MODIFICATION  IN  THE  SHAPE  OP  CONTINENTS. — ATTEMPTS  MADE 

TO  LEARN  THE  FORMER   DISTRIBUTION   OF  SOILS  AND   CLIMATES. OBJECT 

OF   GEOLOGY. — PROVINCE    OF  PHYSICAL  GEOGRAPHY. 

With  regard  to  the  ages  necessary  for  the  accomplishment  of  the  im- 
mense geological  processes,  the  history  of  which  are  disclosed  to  us  in  the 
earth's  strata,  they  certainly  must  have  been  of  prodigious  duration ;  for 
all  the  annals  of  humanity  are  but  as  a  passing  moment  compared  with 
the  cycles  of  the  globe ;  the  cosmogonical  chronology  of  the  Hindoos  can 
alone  give  an  idea  of  the  periods  of  the  earth's  history.  All  the  calcula- 
tions which  astronomers  have  made  as  to  the  duration  of  the  great  planet- 
ary evolutions  result  in  very  formidable  series  of  years,  and  it  is  in  mill- 
ions or  thousands  of  millions  of  centuries  that  estimations  are  made  as  to 
the  duration  of  these  ages.  Professor  Haughton,  a  mathematician,  has  en- 
deavored to  establish,  according  to  the  formula  of  Dulong  and  Petit,  that 
the  mere  fall  in  the  temperature  of  25°,  occurring  pi-eviously  to  the  pres- 
ent epoch  of  our  planet,  would  require  about  1«6  millions  of  years.  In  the 
same  way,  the  formation  of  each  of  the  strata  which  constitute  the  sum- 
total  of  the  geological  records  of  the  earth's  surface  must  have  taken  up 
a  long  series  of  centuries,  before  which  the  mind  recoils  in  perplexity. 

The  unceasing  transformations  of  all  the  rocks  which  compose  the  outer 
layers  of  the  globe  could  not  have  taken  place  without  at  the  same  time 
modifying  the  elevation  and  outline  of  the  land ;  thus  the  general  con- 
figuration of  the  emerged  portions  of  the  surface  has  never  ceased  to 
vary  since  the  first  ages  of  thq^globe.  The  old  mountain  chains  have 
crumbled  down,  stone  by  stone,  and  particle  by  particle,  and  have  been 
distributed,  in  the  form  of  sand  and  clay,  over  plains  and  seas ;  on  the 
other  hand,  ocean-beds  have  gradually  been  elevated,  and  have  changed 
into  dry  land,  which  has  here  and  there  been  upraised  into  hills  and  ranges 
of  peaks.  Strata,  when  scarcely  formed,  were  soon  invaded,  and  made  to 
assist  in  forming  other  strata.  Every  particle,  as  if  caught  in  an  eternal 
eddy,  never  ceased  to  wander  from  rock  to  rock ;  and  consequently,  con- 
tinental masses,  which  are,  indeed,  nothing  but  vast  agglomerations  of 
particles,  must  have  incessantly  shifted  their  positions  on  the  circumfer- 
ence of  the  globe. 

It  would  be  of  the  highest  scientific  interest  if  we  could  follow,  from 
age  to  age,  all  these  shiftings  of  the  outward  features  of  the  earth's  sur- 
face, and  the  oscillations  of  their  elevation  from  century  to  century.  The 
harmony  of  the  continental  structure,  even  now  so  beautiful  to  contem- 
plate, notwithstanding  the  apparent  immobility  of  its  outline,  would  as- 
sume a  dififerent  kind  of  grandeur  if  one  could  see  with  the  mind's  eye  the 


40  THE  EARTH. 

infinite  succession  of  undulations  which  have  rippled  the  surface  of  our 
planet.  Unfortunately,  although  the  direct  investigations  of  geologists 
can  point  out  to  us  those  portions  of  our  present  continents  which  emerged 
at  any  particular  epoch,  they  can  not  disclose  any  thing  to  us  as  to  those 
regions  which,  although  now  buried  by  the  sea,  were  once  elevated  above 
its  surface.  Therefore  the  charts  which  are  prepared  of  any  geological 
period  can  only  be  partial ;  but  still,  these  charts,  incomplete  though  they 
may  be,  are  none  the  less  an  admirable  result  of  ingenious  and  patient  in- 
vestigation. It  is  beautiful,  after  an  unknown  lapse  of  centuries,  to  be  ena- 
bled to  recognize,  among  all  the  various  continental  regions,  those  which 
were  raised  above  the  sea  at  the  same  epoch,  and  thus  dimly  to  trace  out 
some  of  the  features  of  the  ancient  architecture  of  the  globe. 

The  fault  of  many  geologists,  in  their  too  great  hurry  to  fix  the  com- 
mencement of  the  present  period,  has  been  that  they  have  looked  upon 
these  first  beds  of  our  continents  as  being  the  only  land  which  existed  at 
this  epoch  of  our  planet.  It  is  quite  possible  that  there  was  a  time  when 
the  whole  surface  of  the  globe  was  covered  with  water,  and  that  the  first 
land  was  nothing  but  a  mere  shoal ;  then,  perhaps,  that  islets,  and  then 
islands  made  their  appearance,  and,  grouping  themselves  into  archipela- 
gos, ultimately  united  into  continents.  But  nothing  warrants  the  idea 
that  during  the  formation  of  the  strata  examined  by  geologists,  the  pro- 
portion between  land  and  water  has  sensibly  changed.  Fresh  land  may 
have  risen  up  at  points  where  an  examination  of  the  strata  proves  that 
the  ocean  once  flowed ;  but  to  make  up  for  this,  there  are  numbers  of  facts 
which  bear  witness  to  the  disappearance  under  the  water  of  vast  tracts 
of  country.  Age  after  age,  the  general  plan  of  continents  has  been  con- 
tinually modified ;  our  plains,  and  even  our  very  mountains,  have  been 
covered  with  the  waters  of  the  sea;  while  chains  of  hills  and  plateaux  rose 
high  up  in  latitudes  of  the  globe  where^he  waves  of  the  ocean  are  now 
rolling.  In  order  to  ascertain  approxim^ely  the  former  extension  of  con- 
tinents across  our  present  seas,  geologists  have  one  means  at  their  com- 
mand— that  of  establishing  the  perfect  harmony  of  the  various  strata  of  a 
formation  broken  through  and  disconnected  by  the  waves.  For  instance, 
between  France  and  England,  the  correspondent  character  of  the  strata 
on  the  two  shores  of  the  Straits  of  Dover  is  plainly  evident. 

The  fossil  remains  which  are  found  accumulated  at  certain  spots  in  the 
earth  whither  the  currents  have  borne  them,  likewise  prove  the  ancient 
extent  of  some  countries  which  are  now  reduced  to  very  small  dimen- 
sions. Thus  Attica,  which  in  the  present  epoch  is  a  mere  rocky  promon- 
tory of  the  Greek  peninsula,  must  certainly,  in  the  Miocene  period,  have 
formed  a  part  of  a  continent  presenting  vast  plains,  wide-spreading,  grassy 
prairies,  and  thick  forests,  which  must  have  extended  across  the  space 
now  occupied  by  the  Archipelago  and  a  portion  of  the  Mediterranean  Sea, 
stretching  away  far  enough  to  unite  itself  to  Africa.  This  is  the  tale  told, 
in  a  way  evident  enough  to  geologists,  by  the  remains  of  gigantic  animals 
found  in  the  Pikermi  deposits.     The  droves  of  hipparions,  like  those  of 


EVIDENCE  OF  FOSSILS. 


41 


MiocotnUm^tds . 


lirUcajrBtcLt:. 


W^  WcaZdy. 


P?7?a 


Fig.  6.  The  Weald  of  Kent  and  the  opposite  French  Coast 


the  wild  horses  of  South  America,  the  flocks  of  antelopes  of  various  spe- 
cies, the  tall  giraffes,  the  mastodons,  the  rhinoceros,  the  powerful  Dinothe- 
rium,  the  formidable  Machairodus,  stronger  than  the  lion  of  the  Atlas,  and 
so  many  animals  of  large  size,  the  fossil  bones  of  which  are  kneaded  into 
the  soil,  could  not  have  existed  on  mountains  either  entirely  bare  or  thin- 
ly sprinkled  with  scanty  shrubs,  and  in  the  narrow  valleys  which  form 
the  Attica  of  our  day.  No,  they  required  a  vast  continent  like  that  of 
Africa,  where  we  still  see,  in  the  portions  not  yet  invaded  by  the  white 
man,  such  prodigious  multitudes  of  hippopotami,  elephants,  antelopes,  ze- 
bras, and  buffaloes.* 

The  fossils  of  the  two  series,  animal  and  vegetable,  serve  to  prove  still 
more  directly  the  former  existence  of  lands  which  have  now  disappeared. 
In  fact,  if  we  find  the  same  fossil  species  in  the  corresponding  geological 
strata  of  islands  and  continents  which  are  at  present  separated  by  arms 
of  the  sea,  and  subject  to  different  conditions  of  climate,  we  may  natural- 
ly conclude  that  the  regions  in  which  these  species  existed  were  once 
united.  A  harmony  of  this  sort  between  the  Fauna  and  Flora  have  ena- 
bled geologists  to  establish  the  fact  of  the  former  existence  of  Jand  joining 
England  and  Ireland,f  Ireland  and  Spain,J  and  even  Europe  and  America. 

In  exploring  the  lignite  beds  of  the  Tertiary  formation  in  Europe,  geol- 
ogists have,  in  fact,  found  fossil  tulip-trees,  the  remains  of  the  Louisiana 
cypress  {Taxod'mm  distichitm),  seeds  of  the  Robinanuts  of  a  United  States 
species,  leaves  of  the  maple,  oak,  poplar,  pine,  magnolia,  sassafras,  an^  tax- 
us ;  also  of  the  sequoia — those  giants  of  the  Californian  forests,  and  other 

*  AU)ert  Gaudry,  Animaux  fossilen  de  Pikermi. 

t  Murchison,  Anniversary  Address,  18G3.  t  Edward  Forbes. 


42  *  THE  EARTH. 

North  American  trees,  which  do  not  now  exist  in  European  forests.  Half 
way  between  the  two  continents,  the  lignites  of  Iceland  present  an  analo- 
gous fossil  vegetation.  Unless  a  continent,  or  at  least  a  series  of  adjacent 
islands,  had  served  as  a  bridge  across  the  wide  Atlantic,  how  was  it  possi- 
ble for  these  American  trees  to  have  invaded  the  land  of  Europe  ?  In  the 
same  way,  in  the  Miocene  strata  of  Nebraska,  remains  have  been  found  of 
the  rhinoceros,  the  machairodus,  and  the  palseotherium — that  is,  exactly 
the  same  animal  fossils  as  in  the  corresponding  beds  in  Europe.  The  for- 
mer existence  of  an  identical  system  of  organic  life  in  two  continents,  now 
so  entirely  distinct  in  their  Fauna  and  Flora,  gives  us  the  right  to  assume 
that,  at  the  epoch  of  the  Tertiary  lignite,  the  scattered  lands  and  the  few 
clumps  of  mountains  which  formed,  as  it  were,  the  rudiments  of  our  Eu- 
rope, were  connected  with  the  American  coast  by  an  isthmus,  separating 
the  waters  of  the  Atlantic  from  those  of  the  Frozen  Ocean.  This  isthmus 
was  the  Atlantis,  and  the  traditions  which  Plato  speaks  of  about  this  van- 
ished land  were  perhaps  based  upon  authentic  testimony.  It  is  possible 
that  man  may  have  witnessed  the  submergence  of  this  ancient  continent, 
and  that  the  Guanches  of  the  Canary  Islands  were  the  direct  descendants 
of  the  earliest  inhabitants  of  this  primeval  land.* 

At  a  still  more  ancient  epoch,  when  the  fossils  which  are  now  found  in 
the  beds  of  the  Jura  foi-mation  were  still  being  deposited  at  the  bottom 
of  the  sea,  the  Atlantic  was  in  existence,  but  of  very  diflferent  dimensions. 
It  would  appear  that  during  these  ages  of  the  earth's  history  a  vast  con- 
tinent, including  the  two  Americas,  Africa,  the  Indies,  and  New  Zealand, 
extended  in  an  oblique  direction  as  regarded  the  equator  between  the  t^o 
great  oceans  of  the  north  and  south.  This  continent,  which,  like  the  land 
at  the  present  time,  covered  scarcely  a  third  of  the  surface  of  our  plan- 
et, separated  by  its  enormous  mass  many  of  those  gulfs  in  which  the  re- 
mains of  organized  beings  were  being  deposited ;  this  is  proved  by  the 
fact  that  the  Jura  formations  of  Texas,-  in  the  same  latitude  as  those  of 
Southern  Europe,  do  not  present,  among  the  few  fossils  they  contain,  the 
remains  of  those  numerous  species  of  the  Old  World  which,  like  their  con- 
geners of  the  present  epoch,  travel  to  very  considerable  distances.  If 
there  had  been  no  obstacles  between  the  two  basins,  this  absolute  contrast 
between  the  two  Faunas  would  have  been  impossible.  In  the  same  way, 
the  species  of  the  Jurassic  formations  of  South  Africa  are  completely  dif- 
ferent from  those  of  the  Himalaya,  Persia,  and  Europe ;  this  must  lead  to 
the  admission  of  the  former  existence  of  an  intervening  continent  which 
prevented  the  migration  of  living  creatures.  Finally,  the  Australia  of  our 
own  day  presents,  both  in  its  Flora  and  Fauna,  the  very  greatest  similari- 
ty to  the  animals  and  plants  which  lived  in  the  Jurassic  seas  of  Europe 
and  on  their  shores.  In  looking  at  the  kangaroos  of  Australia,  which  re- 
mina  us  of  the  marsupials  of  the  Jurassic  formations  of  England,  and  the 
strange  ornithorhynchus,  scarcely  less  fantastic  in  its  shape  than  the  an- 
•  cient  pterodactyle,  half  bird,  half  batrachian,  or  than  the  problematical 
*  Unger,  Die  versunkene  Insel  Atlantis.     Oswald  Heer,  Klee,  Gaudry,  etc. 


OLD  CONTINENTS.  •  43 

ArchcBopterix  of  Solenhofen,  one  can  hardly  refrain  from  the  belief  that 
Australia  once  formed  a  part  of  the  ancient  Jurassic  continent.  Besides, 
the  coast  of  New  Holland  is  the  place  where  we  now  find  the  only  living 
representatives  of  Trigonia  which  once  inhabited  the  Jurassic  seas.* 

Round  the  inland  sea  which  has  now  become  our  present  Europe,  the 
great  continental  mass  threw  out  a  large,  crescent-shaped  peninsula,  at  the 
origin  of  which  was  the  mouth  of  a  considerable  river,  the  delta  of  which 
may  still  be  traced  out  from  the  coast  of  the  English  Channel  as  far  as 
Westphalia.  On  the  sheet  of  water  which  this  peninsula  protected  from 
the  freezing  winds  of  the  polar  zone,  warmed,  too,  as  it  was,  by  the  heat 
of  the  equatorial  lands,  the  mean  temperature  must  have  been  much  high- 
er than  it  now  is  in  the  corresponding  portion  of  the  earth ;  it  was,  with- 
out doubt,  more  than  68°  Fahr,,  if  we  may  judge  by  the  presence  of  the 
ichthyosaurus  and  plesiosaurus.f  It  must,  however,  be  understood  that 
the  outlines  and  various  conditions  of  these  long-vanished  regions  are  still 
very  far  from  being  known  with  any  degree  of  certainty,  and  it  will  per- 
haps require  centuries  of  investigation  before  a  chart  of  the  Jurassic  con- 
tinent could  be  satisfactorily  drawn  up. 

Circumstances  very  similar  to  those  which  have  enabled  us  to  form 
some  approximate  idea  as  to  the  temperature  of  Europe  in  the  Jurassic 
period  have  also  permitted  savants  to  venture  on  some  general  indica- 
tions relative  to  the  fluctuations  of  climate  which  are  presented  by  the 
other  great  periods  in  the  earth's  history.  Thus  the  mean  temperatui'e 
of  Europe  was  first  mild ;  then,  during  the  Siluinan  ages,  it  became  gradu- 
ally raised ;  in  the  period  of  the  Carboniferous  formations  the  climate  was 
very  warm  and  very  damp,  because  the  greater  part  of  the  land,  then 
mostly  situate  in  the  torrid  zone,  consisted  of  an  uninterrupted  series  of 
archipelagos.  The  epoch  of  the  Trias  was  comparatively  cold,  on  account 
of  the  great  extension  of  the  continent  toward  the  poles.  After  the  ages 
of  the  Jura  formations,  which  were  very  warm  and  very  dry,  came  in  suc- 
cession a  temperate  period,  that  of  the  Chalk ;  then  an  epoch  of  heat,  the 
Eocene ;  and  then  times  of  cold,  gradually  increasing  up  to  the  Glacial 
period ;  after  which  the  temperature  again  increased.  This  is  a  very 
brief  abstract  of  the  succession  of  climates  in  the  region  which  is  now  Eu- 
rope, following  the  inferences  which  Lyell,J  Marcou,§  Oswald  Heer,||  and 
other  savants  have  drawn  from  the  facts  which  they  have  observed  and 
carefully  classified. 

We  thus  see  what  grandeur  there  is  associated  with  the  labor  of  the 
geologist.  Starting  from  the  increasingly  profound  study  of  the  present 
strata,  the  science  of  geology  has  adopted  as  its  task  to  reconstitute  the 
varying  forms  of  continents  and  seas  in  each  of  the  successive  periods  of 
the  history  of  the  globe;  it  follows  out,  in  the  various  epochs,  the  courses 
of  the  winds  and  the  currents,  which  also  have  shifted  with  the  continents 

*  Marcoa,  Rochet  du  Jura,  p.  331.  t  Roches  du  Jura,  p.  826  seq. 

X  Manual  of  Geology.  §  Roches  du  Jura,  p.  335  seq. 

II  Tertidr-Flora  der  Schvodz. 


44  *  THE  EARTH. 

themselves;  it  endeavors  to  measure,  as  if  with  the  thermometer,  the  tem- 
peratures which  have  prevailed  in  different  ages  in  the  various  countries 
of  the  earth;  finally,  it  seeks,  by  all  the  connecting  links  which  the  scat- 
tered debris  can  afford,  to  trace  out  the  marvelous  filiation  of  animal  and 
vegetable  species  from  the  earliest  fossils — of  which  all  that  has  been  dis- 
covered is  but  a  faintly-marked  impress — down  to  the  innumerable  beings 
which  now  stock  our  earth.  Still  dissatisfied  with  the  ideal  she  has  aspired 
to,  science  entertains  the  hope  that  she  will  one  day  be  able  to  point  out 
the  exact  conditions  under  which  every  organism  was  developed  in  the 
periods  gone  by,  and  that  she  will  be  able  even  to  specify,  as  regards  fish- 
es, shells,  and  sea-weeds,  the  depth  of  the  water  in  which  these  beings 
once  lived.  The  astronomer  explores  the  boundless  infinities  of  space ; 
the  geologist  penetrates  into  the  abyss  of  time. 

The  investigation  of  various  rocks  testifies  more  and  more  to  the  pro- 
digious activity  of  the  forces  which  are  ever  remodeling  the  earth.  Just 
as  our  planet,  like  all  its  sister  orbs  and  all  the  stars  of  heaven,  is  borne 
on  in  eternal  motion,  so  all  the  particles  composing  the  mass  of  the  globe 
are  incessantly  changing  their  place,  and  are  circulating  without  repose 
in  a  cycle  no  less  harmonious  than  that  of  the  heavens.  In  the  first  en- 
velope of  the  earth,  the  atmospheric  ocean  which  sustains  the  life  both  of 
animals  and  plants,  continual  eddies  of  winds,  blowing  from  the  pole  to 
the  equator  toward  all  points  of  the  horizon,  are  continually  circulating. 
In  the  great  ocean,  too,  of  waters,  every  drop  also  rolls  on  from  sea  to 
sea,  and  from  the  wave  is  borne  up  to  the  cloud,  and  from  the  cloud  de- 
scends to  the  river.  The  so-called  solid  portion  of  the  planet  is  not  less 
mobile  than  the  atmosphere  and  the  water,  though  the  shifting  action  of 
its  i)articles  is  slower ;  sometimes,  perhaps,  when,  in  a  short  interval  of 
days,  years,  or  centuries,  man  has  failed  to  see  any  vast  modifications  ac- 
complished, he  is  tempted  to  say  that  the  earth  is  immutable.  Was  there 
not  a  time  when  he  also  designated  2i9,  fixed  stars  those  distant  luminaries 
which  nevertheless  move  through  ether  with  so  prodigious  a  rapidity  ? 

Rocks,  mountains,  and  continents  are  all  in  a  jjerpetual  state  of  change, 
and  their  particles  move  round  and  round  the  globe  like  the  water  and 
the  air.  By  the  action  of  torrents  and  atmospheric  agencies,  mouirtains 
are  crumbled  down  and  carried  away  into  the  ocean ;  new  regions  are  up- 
heaved out  of  the  water,  while  others  slowly  sink  and  are  finally  sub- 
merged ;  the  earth  itself  is  rent  open,  and  gas  and  the  molten  matter  of 
vast  strata  make  their  escape.  Finally,  in  consequence  of  the  incessant 
chemical  reactions  going  on  within  the  bowels  of  the  earth,  the  composi- 
tion of  the  rocks  themselves  is  changed,  and  growths  of  crystals  follow 
one  another  in  the  metamorphosed  stone,  just  as  the  Fauna  and  Flora  on 
the  soil  above.*  An  exchange  of  matter  is  likewise  going  on  between  the 
earth  and  the  celestial  spaces,  as  is  proved  by  the  trains  of  burning  stones 
which  become  detached  from  meteoric  bodies  rushing  through  the  atmos- 
phere, and  the  tails  of  comets,  through  the  invisible  waves  of  which  the 
*  Otto  Volger,  Erdbeben  der  Schweiz,  vol.  ii.,  p.  20. 


GENESIS  OF  THE  EARTH.  45 

earth  occasionally  passes.  Planetary  vitality,  like  every  other  vitality,  is 
!i  continual  genesis^  an  incessant  eddy  of  particles,  at  one  time  fixed,  at  an- 
other free,  which  pass  from  one  organism  to  another.  Nevertheless,  in 
whatever  aspect  of  its  infinite  modifications  the  earth  is  contemplated,  it 
is  ever  beautiful  in  its  form,  and  its  consecutive  phenomena  take  place 
with  a  marvelous  harmony. 

Physical  geography,  in  confining  itself  to  the  present  epoch,  merely  de- 
scribes the  earth  as  it  is  existing  before  our  eyes.  Its  aim  is  not  so  am- 
bitious as  that  of  geology,  which  tries  to  recount  the  history  of  our  planet 
during  the  long  succession  of  ages ;  but  still,  it  is  geography  which  col- 
lects and  classes  the  facts ;  she  it  is  that  discovers  the  laws  both  of  the 
formation  and  the  destruction  of  strata.  She  opens  out  a  path  for  geol- 
ogy to  travel  over,  and  each  of  her  advances  in  the  knowledge  of  existing 
phenomena  helps  to  render  easier  some  victory  of  the  human  intellect 
over  the  past  history  of  the  globe.  Without  her  aid  it  would  have  been 
impossible  even  to  have  ventured  the  initiative  step  into  the  labyrinth  of 
vanished  as:es. 


PAKT   11. 
THE    LAND. 


CHAPTER  VI. 


KEGULAK  DISTKIBUTION  OF  CONTINENTS. — IDEAS  OF  ANCIENT  NATIONS  ON 
THIS  POINT. — HINDOO  LEGENDS. — ATLAS  AND  THE  GIANT  CHIBCHACUM. — 
homer's  shield. — STEABO. 

The  globe  of  our  earth  is  in  evident  conformity  to  all  the  laws  of  har- 
mony, both  in  the  spherical  uniformity  of  its  shape,  and  also  in  its  con- 
stant and  regular  course  through  space.  It  would,  therefore,  be  incom- 
prehensible if,  on  a  planet  so  rhythmical  in  all  its  methods,  the  distribu- 
tion of  continents  and  seas  had  been  accomplished,  as  it  were,  at  random. 
It  is  true  enough  that  the  outlines  of  coasts  and  mountain  ridges  do  not 
constitute  a  system  of  geometrical  regularity ;  but  this  very  variety  is  a 
proof  of  a  higher  vitality,  and  bears  witness  to  the  multiplicity  of  motions 
which  have  co-operated  in  the  adornment  of  the  earth's  surface. 

The  uneven  and  yet  harmonious  configuration  of  the  continents  is,  as  it 
were,  the  visible  representation  of  the  laws  which,  for  a  long  series  of  cen- 
turies, have  ruled  in  the  external  modeling  of  our  planet.  "  There  is  not 
a  fundamental  line  in  the  outline  of  the  earth  which  is  not  a  line  of  ge- 
ometry."* ^ 

So  long  as  the  greater  part  of  the  surface  of  the  globe  was  unknown  to 
geographers,  and  they  were  ignorant  of  the  true  form  of  the  earth,  it  may 
be  easily  understood  that  man,  embracing  in  his  feeble  glance  but  a  lim- 
ited horizon,  should  bave  recognized  nothing  but  chaos  in  the  intricate 
net-work  of  geographical  lines.  It  was  impossible  for  them  to  tak^  into 
account  the  laws  which  had  influenced  the  distribution  of  continents,  be- 
cause they  were  ignorant  of  their  very  outlines;  as  the  analysis  of  the  va- 
rious terrestrial  forms  was  not  yet  completed,  they  were,  of  course,  una- 
ble to  accomplish  the  synthesis  of  them  except  by  making  unproved  as- 
sertions, or  by  speculations  in  miraculous  cosmogonies. 

At  all  events,  nations,  in  their  infancy,  being  well  assured  beforehand  of 
tfce  vitality  of  the  bountiful  earth  which  supported  them,  have,  without 
exception,  looked  upon  nature  as  an  immense  organism  endowed  with  su- 
preme beauty.  For  some,  nature  was  an  animal ;  for  others,  she  was  a 
plant ;  for  all,  she  was  an  incorporated  god.  The  ideas  which  they  formed 
on  this  point  are  in  general  the  most  precious  matter  which  is  handed 
*  Jean  Reynaud,  Terre  et  del,  p.  20. 


HARMONY  OP  THE  CONTINENTS.  47 

down  in  their  traditions,  either  oral  or  written ;  for  in  these  legends,  in 
which  they  display  the  loftiest  manifestations  of  their  poetical  genius, 
they  sum  up  their  persuasions  as  to  the  origin  both  of  the  earth  and  also 
of  their  own  race.  For  the  comparative  study  of  the  history,  manners, 
and  ideal  of  every  nation,  no  book  could  be  more  useful  than  one  which 
would  contain  all  the  cosmogonical  conceptions  which  have  been  devised 
down  to  our  own  times.  But,  as  may  easily  be  understood,  these  legends 
are  more  simple  and  rudimentary  in  their  nature,  jtist  in  proportion  as  the 
cosmical  features  among  which  they  were  conceived,  and  of  which  they 
are  in  a  great  part  the  reflection,  were  more  subdued  in  their  manifesta- 
tions and  phenomena.  The  people  of  the  extreme  north,  who  are  in  the 
habit  of  digging  out  subterranean  habitations  in  order  to  avoid  the  cold, 
their  country  being  for  a  great  part  of  the  year  covered  with  ice  and  snow, 
can  not  have  their  ideas  as  to  the  harmony  of  the  globe  inspired  by  the 
same  conceptions  as  the  men  of  the  south,  who  dwell  at  the  foot  of  the 
highest  mountains  in  the  world,  and  constantly  contemplate  all  the  great 
phenomena  of  planetary  life — monsoons,  hurricanes,  the  sudden  overflows 
of  rivers,  and  the  rapid  increase  of  immense  tropical  forests.  To  the  Hin- 
doos, every  thing  in  nature  is  motion,  never-ceasing  creation,  and  startling 
activity.  According  to  one  of  their  books,  Brahma,  the  %ternal  laborer, 
created  the  earth  while  surveying  his  own  reflection  in  the  ocean  of  sweat 
that  had  fallen  from  his  brow. 

The  Hindoo  legends  as  to  the  formation  of  the  earth  and  the  distribu- 
tion of  continents  are  very  numerous ;  besides,  most  of  these  hypothetical 
cosmogonies  are  remarkable  for  their  boldness  and  for  the  deep  convic- 
tion they  manifest  of  the  vitality  which  animates  the  earth,  and  all  that 
it  contains.  However  strange  some  of  these  grandly  poetical  theories 
may  seem  to  us,  they  are  not  on  this  account  any  less  true  than  the  dry 
systems  of  mere  nomenclature  in  which  certain  unhappy  scholars  have 
considered  the  whole  scheme  of  geography.  According  to  an  ancient 
Hindoo  belief-^very  similar  to  that  of  several  of  the  American  nations — 
the  earth  is  nothing  but  a  burden  placed  on  a  gigatitic  elephant,  the  sym- 
bol of  intelligence  and  wisdom;  while  an  immense  tortoise,  representing 
the  still  rude  forces  of  nature,  bears  the  enormous  animal  over  a  shoreless 
sea  of  milk,  boundless  as  infinity. 

Subsequently,  the  ideas  which  the  Hindoos  formed  as  to  the  origin  of 
the  globe  were  singularly  diversified,  according  to  the  various  epochs  and 
sects.  The  Brahmins  fancied  that  the  earth  was  a  full-blown  lotus,  float- 
ing on  the  surface  of  the  waters.  The  two  peninsulas  of  the  Ganges  and 
the  other  Asiatic  countries  are  the  expanded  flower,  the  isles  scattered 
over  the  ocean  are  the  half-opened  buds,  distant  lands  are  the  softly  spread- 
ing leaves.  The  Ghauts  and  the  Neilgherries  are  the  stamens  of  the  im- 
mense flower,  while  in  the  midst  culminates  the  lofty  Himalaya,  the  sacred 
pistil^  in  which  are  organized  the  seeds  of  the  world.  Man,  like  the  tiny 
insect  which  sees  infinity  in  a  rose,  builds  his  imperceptible  cities  near  the 
honey-cups  of  the  flower,  and  someCimes  spreads  his  wings  to  glide  over 


48  y^^  EARTH. 

the  sea  from  the  corolla  of  the  Indies  to  that  of  Ormuz  or  Socotora.  The 
stalk  of  the  plant  disappears  in  the  depths  of  the  ocean,  and,  descending 
from  abyss  to  abyss,  at  last  buries  itself  in  the  very  heart  of  Brahma. 

This  fantastic,  but  yet  somewhat  grand  conception,  which  at  least  at- 
tributed to  the  earth  some  degree  of  motion  and  life,  is  very  superior  to 
all  the  dogmatic  theories  of  the  Syrian  priests  and  the  Hebrew  Talmudists ; 
the  latter,  in  their  terror  of  change,  looked  upon  the  terrestrial  mass  as  an 
immovable  block  solidly  based  on  immense  columns  of  stone  or  metal, 
which  were  themselves  lost  in  primitive  chaos.  These  ancient  and  coarse 
hypotheses  are  met  with  again  in  the  more  noble  myth  of  the  Greeks,  ac- 
cording to  which  the  globe  was  placed  upon  the  shoulders  of  a  kneeling 
giant.  This  was  an  idea  which  was  in  full  harmony  with  the  plastic  ge- 
nius of  Greece,  which  ever  sought  to  recognize  in  every  thing  the  propor- 
tions of  the  human  form,  deified,  as  it  was,  by  strength  and  beauty.  The 
idea,  in  the  main,  had  remained  much  the  same,  but  it  had  assumed  a 
shape  which  was  more  poetic,  and  consequently  more  in  conformity  to  the 
genius  of  an  infant  nation.  Imbued  with  similar  ideas,  the  aborigines  of 
the  plateau  of  Bogota  tell  how,  in  punishment  for  some  crime,  the  good 
goddess  Bochica  condemned  the  giant  Chibchacum  to  bear  upon  his  shoul- 
ders the  burdeif  of  the  earth,  which  previously  rested  upon  pillars  of  the  lig- 
num-vitce  wood.  Earthquakes,  therefore,  were  derived  from  no  other  cause 
than  the  wearied  or  impatient  movements  of  this  Atlas  of  the  New  World.* 

With  regard  to  the  ideas  in  respect  to  the  distribution  of  continents  and 
seas  over  the  surface  of  the  globe,  they  could  hardly  fail  to  be  erroneous, 
inasmuch  as  they  took  their  rise  among  nations  who  endeavored  to  form 
a  judgment  as  to  the  whole  of  the  earth  by  means  only  of  the  few  coun- 
ti'ies  which  were  known  to  them. 

According  to  the  poems  of  Homer,  which  are  imbued  with  the  ideas  of 
the  ancient  Greeks  as  to  nature,  and  also  mankind  and  their  ways,  the 
earth  is  a  great  disk,  elevated  at  the  edges  by  a  lofty  girdle  of  mountains, 
round  which  the  river  Ocean  rolled  its  swelling  waves.  In  the  centre  of 
the  disk  Olympus  towered  up  with  its  three  rounded  summits,  on  which 
stood  the  mansions  of  the  ever-happy  gods,  and  Jupiter,  throned  on  its 
loftiest  crest,  looked  down  through  the  clouds  and  saw  the  restless  crowd 
busy  at  his  feet.  The  land,  divided  into  two  halves  by  the  blue  sheet  of 
the  Mediterranean,  stretched  far  away  to  the  very  verge  of  the  disk,  like 
the  raised  figures  which  ornament  the  front  of  a  shield.  Down  from  the 
heights  of  Olympus  the  immortals  contemplated  in  one  glance  all  the  pen- 
insula of  Greece,  the  white  isles  of  the  Archipelago,  the  coasts  of  Asia  Mi- 
nor, the  plains  of  Egypt,  the  mountains  of  Sicily,  inhabited  by  the  Cy- 
clops, and  the  Pillars  of  Hercules — the  boundary-stones  of  the  ancient 
world.  All  round,  above  the  tract  inhabited  by  man,  stretched  the  crys- 
tal dome  of  the  firmament,  borne  up  by  the  two  columns  of  Atlas  and 
Caucasus. 

But  the  discoveries  of  travelers  and  the  calculations  of  the  Greek  as- 
*  BoUaert,  Antiquarian  Researches,  p.  12. 


EARL  T  IDEAS  OP  THE  EARTH. 


49 


tronomers  must  have  gradually  modified  this  primitive  theory.  Strabo, 
who  was,  however,  one  of  the  greatest  travelers  of  antiquity,  having  trav- 
ersed the  earth  from  the  mountains  of  Armenia  to  the  shores  of  the  Tyr- 
rhenian Sea  and  the  Euxine,  and  to  the  frontiers  of  Ethiopia,  had  already 
formed  a  very  just  idea  of  the  real  distribution  of  the  continents  of  the 
ancient  world,  and  discussed  with  wonderful  sagacity  their  mutual  rela- 
tions. Overstepping  the  limits  of  the  regions  already  known,  he  went  so 
far  as  to  hazard  the  assertion  that,  between  western  Europe  and  eastern 


Fig.  6.  The  World  after  the  poetic  acconnts  of  Homer. 

Asia,  there  existed  an  inhabited  land  forming  an  equipoise  to  the  Old  World. 
In  all  his  scientific  audacity,  he  conjectured  that  which  modem  geography 
has  since  discovered — that  "  not  only  mere  masses  of  rock  and  islands, 
large  or  small,  but  also  whole  continents,  may  be  upheaved  from  the  bed 
of  the  sea."  •  As  the  great  Ritter  has  stated,  with  a  feeling  which  may  al- 
most be  called  filial,  Strabo  is  the  real  founder  of  geographical  science,  and 
modern  savants  have  only  resumed  his  work,  after  so  many  centuries  smit- 
ten with  sterility,  first  by  the  Roman  Caesarisra,  and  subsequently  by  the 
barbarism  of  the  Middle  Ages. 

D 


50 


TEE  EAMTH. 


CHAPTER  Vn. 

INEQUALITY  OF  LAND  AND  WATER. — THE  OCEANIC  HEMISPHERE. — THE  CON- 
TINENTAL HEMISPHERE. — THE  SEMICIRCLE  OP  LAND. — DISTRIBUTION  OF 
THE  HIGHEST  PLATEAUX  AND  LOFTIEST  MOUNTAIN -CHAINS  ROUND  THE 
INDIAN  AND  SOUTHERN  OCEANS. — POLAR  CIRCLE. — CIRCLE  OF  LAKES  AND 
DESERTS. — COASTS   ARRANGED   IN  ARCS    OF   A   CIRCLE. 

The  most  prominent  fact  which  strikes  an  observer  in  an  examination 
of  the  superficies  of  the  earth  is  the  unequal  extent  of  the  ocean  and  of  the 
land  which  has  emerged  from  it.  Although  at  the  two  polar  regions 
there  are  still  vast  unexplored  tracts  forming  about  a  sixteenth  of  the  ter- 
restrial surface,  still  it  may  be  approximately  stated  that  three  quarters 
of  the  surface  of  the  globe  is  covered  by  sea.     The  plate  gives  an  idea  of 


Fig.  7.  Relative  proportions  of  land  and  water  In  different  latitudes. 


the  distribution  of  land  and  sea  in  the  explored  regions  of  the  globe  from 
75°  north  latitude  to  70°  south.*  An  equilibrium  between  the  two  ele- 
ments exists  only  on  two  parallels  of  the  terrestrial  circle,  one  of  which  is 
in  45°  of  north  latitude,  half  way  between  the  equator  and  the  pole.  In 
this  part  of  the  earth's  circumference,  the  land  occupies  exactly  one  half 
of  the  surface  of  the  globe. 

The  principal  accumulation  of  water  is  in  the  southern  hemisphere,  and 
*  Dove,  Zeitschrift  filr  allgemeine  Erdkunde.     Jan.,  1862. 


LAND  AND  WATER. 


51 


the  continental  masses,  on  the  other  hand,  are  grouped  in  the  northern 
half  of  the  earth's  surface.  This  contrast  between  the  two  divisions  of  the 
globe  becomes  much  more  striking  if,  instead  of  taking  the  two  poles  as  the 
centres  of  our  hemispheres,  two  points  are  chosen  which  are  situated,  one 
in  the  midst  of  the  most  extensive  tracts  of  ocean,  and  the  other  about  the 
centre  of  the  group  of  continents.  If  we  describe  a  great  circle  round 
London,  which  at  the  present  time  is,  in  fact,  the  great  focus  of  attraction 
for  the  commerce  of  the  whole  world,  almost  all  the  continental  surface 


Pig.  8.  Oceanic  HemiBphere. 

surrounding  the  basin  of  the  Atlantic,  rendering  it  almost  an  inland  sea, 
will  fall  within  this  hemisphere.  .  The  other  half  of  the  terrestrial  surface, 
the  centre  of  which  would  be  situated  somewhere  near  New  Zealand,  the 
antipodes  of  Great  Britain,  is  almost  entirely  filled  up  with  the  immensity 
of  water.  The  antarctic  countries — Australia,  Patagonia,  and  the  adja- 
cent archipelagos — form  the  only  land  which  breaks  the  uniformity  of  this 
oceanic  hemisphere.  According  to  a  very  plausible  hypothesis,  this  ex- 
uberance in  the  development  of  continents  on  one  side  of  the  globe,  and 
the  afflux  of  the  waters  of  the  ocean  towards  the  opposite  hemisphere,  are 


52 


TEE  EARTH. 


caused  by  the  unequal  weight  of  the  materials  which  constitute  the  mass 
of  the  globe  and  the  consequent  non-coincidence  between  the  actual  cen- 
tre and  the  centre  of  gravity.* 

The  coast  outline  of  the  continents  which  surround  the  great  ocean 
tends  to  a  form  which  is  perceptibly  circular ;  it  is  a  kind  of  ring,  broken 
in  two  at  the  south  near  the  frigid  zone  of  the  antarctic  circle.  From  the 
southern  point  of  Africa  to  Kamtschatka,  and  from  the  Aleutian  Isles  to 
Cape  Horn,  the  land  is  arranged  in  an  immense  amphitheatre,  the  circum- 


No.  9.  Continental  Hemisphere. 

ference  of  which  is  equal  to  the  circumference  of  the  globe,  and  can  not 
be  less  than  25,000  miles.  They  are  not  merely  low  shores  which  spread 
in  this  hemicycle  round  the  oceanic  hemisphere ;  the  highest  plateaux,  the 
loftiest  mountains  of  the  world,  are  drawn  out  in  a  vast  semicircle  in  those 
countries  which  are  adjacent  to  the  Pacific,  and  tend  to  incline  toward 
that  ocean  the  centre  of  gravity  of  the  whole  of  the  continental  bulk. 

Thus  it  is  along  the  side  of  the  Indian  Ocean,  an  appendage  as  it  is  to 
the  great  Southern  Ocean,  that  Africa  presents  its  loftiest  ridges ;  there, 
*  Herschel,  Physical  Geography,  p.  15. 


NORTH     AMERICA 


PL.  IV 


HAPPEH  6c  BROTHERS.  NEW  YORK 


CONTOUR  OF  THE  LAND. 


53 


Fig.  10.  Baain  of  the  Pacific 

too,  are  found  the  snowy  mountains  of  Kenia  and  of  Kilimandjaro  and  the 
plateau  of  Ethiopia,  like  a  great  fortress  surrounded  by  bastions.  East- 
ward of  the  narrow  entrance  to  the  Red  Sea  stands  another  plateau,  that 
of  the  Yemen,  whose  steepest  slopes  are  likewise  turned  toward  the  shores 
of  the  ocean. 

Farther  on,  this  rampart  of  lofty  ridges,  which  might  well  be  called  the 
"  vertebral  column"  of  the  body  of  continents,  is  interrupted  by  the  de- 
pression of  the  Euphrates  and  the  Persian  Gulf;  but  it  again  commences 
at  the  north  of  Persia.  The  Caucasus,  the  Elburz,  the  Hindu-Kutch,  the 
Karakorum,  and  the  proud  Himalaya,  the  summits  of  which  rise  more  than 
5^  miles  above  the  plains  of  Hindostan,  all  are,  on  an  average,  three  or 
four  times  nearer  to  the  Indian  than  to  the  Arctic  Ocean.  This  difference 
would  be  still  more  increased  if  we  did  not  take  into  account,  as  portions 
of  the  great  Asiatic  body,  the  southern  peninsulas  which  stretch  away  so 
far  into  the  sea.  Taken  as  a  whole,  the  continental  mass  may  be  divided 
into  two  gradients,  one  of  which  descends  rapidly  toward  the  plains  next 
the  Indian  Ocean,  whilst  the  other  side,  ribbed  with  divergent  mountain 
chains,  inclines  more  gradually  toward  the  immense  marshy  tundras  which 
border  the  Frozen  Ocean. 

The  great  plateaux  of  Central  Asia,  bounded  on  the  north  and  south  by 
the  mountain  chains  which  radiate  in  a  fan-like  shape  from  the  knot  of  the 
Hindu-Kutch,  form,  in  the  direction  of  the  northeast,  the  highest  portion 
of  the  continental  amphitheatre ;  then,  in  the  north  of  the  valley  of  the 
Amoor,  they  are  prolonged  up  to  a  short  distance  of  the  coast-line  by 
ranges  of  peaks,  which  tower  over  the  Sea  of  Ochotzk  and  Behring's 
Straits.  Beyond  this  the  waters  of  the  Pacific  have  opened  out  a  passage 
to  join  the  tides  of  the  Frozen  Ocean ;  but  yet  the  line  of  mountains  is 
still  prolonged.  Arranged  as  they  are,  in  the  form  of  a  broken  isthmus, 
on  the  south  of  the  Straits,  the  Aleutian  Isles  unite  the  two  continents  of 
Asia  and  North  America ;  one  might  almost  fancy  them  the  shore-line  of 
some  ancient  and  submerged  land. 


54 


THE  EARTH. 


The  lofty  peninsula  of  Aliaska,  which  follows  on  to  the  Aleutian  range, 
is  the  starting-point  of  the  series  of  highlands  which  border  the  coasts  of 
the  Pacific  along  the  whole  length  of  the  two  American  continents.  Par- 
allel chains,  abutting  in  some  places  on  large  groups  of  mountains,  bend 
round  the  shores  of  Sitka,  British  Columbia,  and  California,  gradually 
merging  into  the  plateau  of  Anahuac.  The  latter  is  prolonged  on  the 
southeast  by  a  volcanic  chain,  here  and  there  interrupted ;  but  on  the 
coasts  of  the  Gulf  of  Darien  the  great  chain  begins  again,  and,  plunging 
the  rocks  which  form  its  base  deep  into  the  waves  of  the  Pacific,  extends 


Fig.  11.  Circnmpolar  Circle. 

its  double  or  triple  snowy  ridges  down  to  the  Straits  of  Magellan.  The 
other  elevations  of  the  surface  of  the  ground  lie  to  the  east  of  this  back- 
bone, as  it  were,  of  the  South  American  continent,  and  attain  a  very  much 
less  considerable  altitude ;  they  are,  indeed,  intersected  and  even  crossed 
by  some  of  the  rivers  which  take  their  rise  in  the  perpetual  snows  of  the 
Andes.  Added  to  this,  the  steepest  slope  of  the  principal  chain  is  uni- 
formly turned  toward  the  coast  of  the  Pacific,  and  the  distance  from  the 
mouths  of  the  Amazon  to  the  summits  of  the  Andes  is  on  the  average,  at 


POLAR  CIRCLE. 


55 


least,  fifteen  times  longer  than  the  short  span  from  the  ridges  of  the  latter 
to  the  shore  of  the  ocean. 

The  immense  semicircle  of  high  land  forming  the  inner  coast-line  of  the 
mass  of  continents  which  extended  from  the  Cape  of  Good  Hope  round  to 
Cape  Horn  is  not,  however,  the  only  evidence  of  the  forces  which  are  al- 
ways in  action,  tending  to  elevate  the  salient  portions  of  the  terrestrial 
sphere,  and  operating  in  great  circular  lines.  Thus  in  the  chain  of  the 
Andes  is  commenced  a  series  of  volcanic  mountains  and  islands  which 
forms  a  vast  circle  round  the  Southern  Ocean.     This  is  the  great  ring  of 


Fig.  12.  Circle  of  Inland  Lakes  and  Seas. 

active  volcanoes  which  was  for  the  first  time  described  by  Leopold  von 
Buch,  and  designated  by  Carl  Rittcr  as  the  "  Circle  of  Fire,"* 

Thus,  also,  the  continental  and  insular  shores  which  are  turned  toward 
the  Arctic  Ocean  assume  a  circular  curve.  As  far  as  it  is  possible  to  judge 
from  the  present  state  of  our  knowledge  as  to  this  part  of  the  world,  it 
appears  as  if  a  polar  circle  inclined  about  five  degrees  toward  Behring's 
Straits  would  have  for  its  almost  regular  circumference  the  northern 
*  Vide  the  chapter  on  "  Volcanoes." 


56 


THE  EARTH. 


coasts  of  Siberia,  of  Parry's  archipelago,  Greenland,  Spitzbergen,  and  Nova 
Zembla. 

Another  circle,  inclined  about  ten  degrees  to  the  pole  in  the  direction 
of  the  meridian  of  Paris,  would  pass  through  the  greater  part  of  the  inland 
seas  of  the  Old  and  New  Worlds.  This  curve  would  enter  the  Mediter- 
ranean through  the  Straits  of  Gibraltar,  and,  crossing  this  sea,  as  well  as 
the  Euxine,  would  unite  the  Caspian  and  the  Sea  of  Aral,  both  of  which, 
during  a  recent  geological  epoch,  formed  but  one  sheet  of  water;  it  would 
then  be  prolonged  toward  the  Pacific  through  the  chain  of  the  chief  Sibe- 
rian lakes,  including  the  Baikal.     On  the  American  continent  the  curve 


Fig.  13.  Semicircle  of  Deserts. 

passes  through  the  Winnipeg  Lake,  the  Mediterranean  of  the  great  lakes 
of  the  St.  Lawrence,  then  the  Champlain  Lake,  and  the  Bay  of  Fundy. 
Thus  terminates  this  great  series  of  continental  depressions,  which  cer- 
tainly was  not  formed  at  random.  On  the  north  of  the  Mediterranean, 
the  most  important  of  all  the  inland  seas,  the  loftiest  mountains  in  Europe 
form  a  rampart  similar  to  that  which  bounds  the  South  American  shore 
of  the  Pacific.  In  fact,  the  Pyrenees,  the  Alps,  and  the  Balkans  form  a 
sort  of  wall,  broken  through  with  numerous  gaps,  which  is  much  nearer  to 
the  Mediterranean  than  to  the  northern  seas,  and  presents  also  its  steepest 
slopes  toward  the  south. 


DESERTS  AND  SEA- COASTS. 


57 


Jean  Reynaud  lias  also  thought  that  he  could  point  out*  the  existence 
of  another  terrestrial  ring,  which  must  likewise  have  been  formed  in  obe- 
dience to  some  great  geological  law.  This  third  circle,  inclined  15°  (or 
rather  20°)  to  the  pole,  passes  through  the  Isthmus  of  Panama,  which  is 
the  deepest  depression  of  the  land  of  America,  and  crosses  almost  all  the 
great  deserts  in  the  Old  World,  many  of  which  were  covered  with  water 
during  the  later  terrestrial  periods.  These  sandy  or  rocky  tracts  are  ar- 
ranged obliquely  across  the  continents  of  Africa  and  Asia,  and  consists  of 
the  Sahara,  the  sandy  districts  of  Egypt,  the  Nefoud  of  Arabia,  the  salt 
plateaux  of  Persia,  and  the  Gobi,  or  Chamo,  the  latter  inferior  in  extent 
only  to  the  African  solitudes.  It  is  a  remarkable  thing  that  this  series  of 
dried-up  seas  is  commanded  on  the  north  by  various  mountain  chains,  the 


Fig.  14.  Western  Shores  of  the  Mediterranean. 


Alps,  the  Taurus,  the  Caucasus,  and  the  AltaK ;  like  the  Pacific  and  the 
Mediterranean,  these  now  vanished  waters  were  bordered  on  the  north  by 
a  rampart  of  high  lands.  Oscar  Peschel  has,  however,  proved  that  the 
phenomena  of  climate  constitute  the  real  cause  of  the  supposed  "  Equator 
of  Contraction,"  and  that  this  semicircle  of  deserts  is  to  be  attributed  to 
the  general  direction  of  the  winds  and  the  scarcity  of  rain. 

Not  only  those  various  regions  which  are  distinguished  by  some  strik- 
ing analogy  in  elevation  and  aspect  are  circularly  arranged  on  the  surface 
of  the  planet,  but  the  mere  outlines  of  the  continents  themselves  seem  to 
be  obedient  to  some  rhythmical  law,  in  conformity  to  which  they  present 
*  Terre  et  Ctel,  Eclair^issements  scientljiques. 


58  THE  EARTH. 

a  series  of  arcs  of  a  circle,  assuming  a  regularity  which  is  sometimes  al- 
most perfect.  The  coasts  of  the  three  southern  continents,  South  Amer- 
ica, Africa,  and  Australia,  afford  remarkable  instances  of  this  rule.  The 
coast-lines  of  all  the  peninsulas  of  the  northern  continent  may  likewise  be 
cut  up  into  arcs  of  a  circle,  and  multitudes  of  islands,  of  which  Sicily  can 
perhaps  be  taken  as  a  type,  may  be  compared  to  actual  curving-sided  tri- 
angles. This  circular  arrangement  of  the  coasts  is  so  frequently  re- 
marked that  many  geologists  have  gone  so  far  as  to  endeavor  to  class  va- 
rious countries  according  to  the  degree  of  the  curvature  of  their  gulfs  and 
bays. 


SOUTH      AMERICA 


PL.V. 


DIVISION  OF  THE  LAND.  59 


CHAPTER  Vm. 

DIVISION  OF  THE  LAND  INTO  THE  OLD  AND  NEW  WORLDS. — DOUBLE  AMERI- 
CAN CONTINENT. — DOUBLE  CONTINENT  OP  EUROPE  AND  AFRICA. — DOUBLE 
CONTINENT  OF  ASIA  AND  AUSTRALIA. 

Although  we  may  consider  the  continental  masses  as  arranged  in  cer- 
tain great  circles  traced  round  the  sphere,  we  must  also  recognize  the  ef- 
fect of  another  law  in  virtue  of  which  the  various  groups  of  land  are  ar- 
ranged in  three  double  continents,  forming  respectively  three  parallel 
series. 

At  first  sight,  it  would  seem  as  if  the  portions  of  the  earth  which  have 
have  emerged  from  the  waters,  form,  in  fact,  but  two  groups — those  of 
the  Old  and  New  Worlds :  and  that  the  shapes  of  these  groups  appear  to 
bear  little  or  no  resemblance  to  one  another.  Yet  a  careful  examination 
can  not  fail  to  reveal  a  striking  unity  of  plan,  where  at  first  sight  all 
seems  disorder  and  chaos.  The  fact  is,  in  consequence  of  the  crossing 
of  the  different  upheaved  portions  of  the  earth— some  in  a  circular  direc- 
tion rfund  the  seas,  others  parallel  to  the  meridian — there  is  produced 
among  the  continental  groups  a  series  of  contrasts  w-hich  so  interfere  with 
the  resemblances,  as  to  cause  that,  in  the  general  distribution  of  the  land, 
opposite  forms  should  successively  predominate.  NeverthHess,  this  med- 
ley, by  its  infinite  variety,  is  the  very  thing  which  gives  so  great  a  har- 
mony to  the  ensemble  of  the  terrestrial  outline. 

In  the  comparative  study  of  the  configuration  of  continents,  we  must 
choose  America  as  our  type,  because  in  this  portion  of  the  world  the  line 
of  upheaval,  tending  from  north  to  south,  forms  a  tangent  to  the  curve 
which  is  described  by  the  disposition  of  the  land  round  the  Pacific,  and 
is  even  coincident  with  it  along  a  certain  portion  of  its  extent.  In  con- 
sequence of  this  coincidence  of  the  axis,  the  New  World  exhibits  a  very 
great  regularity  of  shape.  It  is  composed  of  two  triangles,  each  pointing 
its  apex  toward  the  south,  and  linked  together  by  a  very  narrow  isthmus. 
These  two  halves  of  America,  one  of  which  belongs  entirely  to  the  north- 
em  hemisphere,  the  other  being  ti'opico-meridional,  form  two  perfectly 
distinct  continents,  and  yet  they  show  so  great  a  similarity  of  structure 
that  they  are  evidently  the  counterparts  of  one  another.  Nevertheless, 
as  the  natural  effect  of  the  increasing  divergence  in  North  America  be- 
tween the  continental  axis  and  the  circle  of  mountains  which  spread 
round  the  Pacific,  this  continent  is  much  larger  than  its  companion,  and 
its  coast-line  is  much  more  indented.  The  more  typical  form,  therefore, 
is  that  of  the  southern  continent.  , 

In  the  Old  World,  Africa  evidently  follows  the  same  model  as  South 


QQ  THE  EARTH. 

America.  As  regards  their  general  structure,  the  two  continents  are 
alike  in  their  great  triangular  mass,  with  coasts  slightly  inflected ;  and 
the  similarity  extends  even  to  the  details  of  their  gulfs  and  promonto- 
ries. The  contrasts,  are,  it  is  true,  very  numerous ;  but  they  exhibit  so 
much  regularity  and  rhythm,  so  to  speak,  that  even  in  these  we  can  not 
fail  to  see  a  new  proof  of  unity  of  formation  in  the  two  continental 
masses. 

As  far  as  Europe  is  concerned,  we  should,  at  first  sight,  be  tempted  to 
say  that  there  was  no  degree  of  correspondence  between  this  part  of  the 
world  and  the  North  American  continent.  In  fact,  this  collection  of  pe- 
ninsulas, which  even  in  our  days  is  still  the  most  important  region  of  the 
whole  world,  on  account  of  the  high  civilization  of  the  nations  inhabiting 
it,  might  be  looked  upon  as  nothing  but  a  geographical  appendix — a  mere 
prolongation  of  Asia ;  in  fact,  we  almost  hesitate  to  compare  it  with 
North  America,  the  bulk  of  which  occupies  a  superficies  twice  as  large. 
Yet  a  geological  study  of  the  conformation  of  Europe  proves  that  in  re- 
ality it  forms  a  distinct  continent.  At  some  previous  epoch  it  was  sepa- 
rated from  Asia  by  a  sheet  of  water,  which  stretched  from  the  Mediterra- 
nean to  the  Gulf  of  Obi,  through  the  present  Euxine,  Caspian,  and  Aral 
seas.  At  the  foot  of  the  mountain  chains  of  Oural  and  Altai  extend  those 
immense  steppes  which,  like  most  deserts,  still  retain  much  of  their  former 
oceanic  appearance,  and  form  the  eastern  boundary  of  Europe  quite  as 
effectually  as  would  a  second  Atlantic.  The  arai  of  the  sea  whidi  once 
divided  these  two  divisions  of  the  world  is,  indeed,  dried  up ;  but,  al- 
though now  united,  the  two  lands  none  the  less  retain  their  distinctly  de- 
fined charactqjs. 

Thus,  geology  bears  its  testimony  in  establishing  the  continental  form 
of  Europe  and  its  similarity  to  North  America.  The  resemblance  be- 
tween the  two  quarters  of  the  globe  is  kept  up  on  the  southern  as  well  as 
on  the  eastern  side.  It  is  very  true  that  on  the  southern  side  the  land  of 
Europe  is  no  longer  connected  with  that  of  Africa  by  an  isthmus  similar 
to  that  which  joins  the  two  Americas ;  but,  as  even  Strabo  well  knew, 
an  upheaving  of  scarcely  a  hundred  yards  would  suffice  to  form  a  tongue 
of  land  from  Sicily  to  Tunis,  dividing  the  Mediterranean  into  two  halves. 
A  submarine  bank  separates  this  sea  into  two  deep  basins,  and,  owing  to 
its  steep  elevation,  may  be  considered  as  an  actual  isthmus.  Added  to 
this,  the  northern  part  of  Africa — that  is,  the  region  of  the  Atlas,  com- 
prised between  the  former  sea  of  the  Sahara  and  the  present  coasts  of 
Morocco,  Algiers,  and  Tunis — is  certainly  an  ancient  dependency  of  Eu- 
rope. Modern  science  has  established  the  fact  that,  as  regards  both  its 
Fauna  and  its  Flora,  as  well  as  its  geological  constitution,  the  whole  of 
the  eastern  sea-coast  of  the  Mediterranean — the  north  as  well  as  the  south 
— forms  an  inseparable  whole.  Thus,  M.  Bourguignat  has  clearly  estab- 
lished, by  his  examination  of  living  molluscs,  that  Northern  Africa  does 
not  possess  one  single  species  which  js  peculiar  to  it,  and  that  all  the 
types  of  the  animals  which  are  found  on  the  slopes  of  the  Atlas  proceed 


DOUBLE  CONTINENTS.  gl 

from  the  Iberian  peninsula.  The  western  Sahara  and  Tripoli  being  equal- 
ly devoid  of  any  species  specially  belonging  to  them,  it  becomes  evident 
that  these  latter  regions,  at  the  commencement  of  the  present  epoch,  had 
not  yet  emerged  from  the  bed  of  the  ocean,  and  that  Mauritania  formed 
the  southern  continuation  of  the  Spanish  peninsula;*  the  headlands  of 
Ceuta  and  Gibraltar  then  formed  portions  of  one  and  the  same  chain  of 
mountains.  The  ancients  were  not  ignorant  that  the  western  entrance  to 
the  Mediterranean  had  once  been  closed,  since  they  attributed  to  Hercules 
the  honor  of  having  opened  the  gate  between  the  two  seas.  Many  au- 
thors even  regarded  it  as  a  vexatious  innovation  that  the  geographers 
had  made  Europe  and  Libya  two  distinct  parts  of  the  world ;  for  although 
separated  by  the  sea,  the  two  regions  appeared  to  them  to  belong  to  the 
same  geographical  whole.f 

The  external  outlines  of  Europe  remind  one  forcibly  of  those  of  North- 
ern America.  In  both  continents,  the  coasts  which  border  on  the  Atlan- 
tic are  deeply  indented,  and  not  only  allow  the  sea  to  penetrate  a  long 
way  into  the  interior  of  the  land  in  various  places,  but  also  throw  out  pe- 
ninsulas far  into  the  ocean.  In  Europe,  the  Mediterranean  and  the  Baltic 
Sea  correspond  with  the  Gulf  of  Mexico  and  all  those  seas  which  extend 
between  Greenland  and  British  America.  But  it  must  be  remarked  that 
in  Europe,  the  arrangement  of  which  is  finer  and  more  delicate  than  that 
of  any  other  part  of  the  world,  the  peninsulas  are  more  slender  in  form, 
and  the  inland  seas  more  surrounded  with  land.  In  Europe,  the  penin- 
sulas have  become  islands,  and  the  seas  have  become  lakes.  Nevei'the- 
less,  Europe  corresponds  in  its  structure  with  North  America  to  a  great 
extent,  and  forms,  with  Africa,  a  second  pair  of  twin  continents,  parallel 
to  those  of  the  New  World. 


15.  Terra  quadrifUa. 


Asia  and  Australia  constitute  the  third  pair  of  continents,  although 
their  form  only  very  imperfectly  reproduces  the  primitive  type.  There 
is  an  interruption  of  equilibrium  to  the  great  advantage  of  the  northern 
portion ;  but  in  the  general  configuration  of  these  great  masses  we  can 
still  discern  the  principal  features  which  distinguish  the  other  double 
continents.  Like  North  America  and  Europe,  Asia  is  geologically  iso- 
lated ;  like  these  two  parts  of  the  world,  she  throws  out  numerous  penin- 

*  Bourguignat,  La  Malacologie  de  VAlgirie. 

t  Sallust,  Bell.  Jug.,  c.  17 ;  Von  HoflF,  Veranderungen  der  Erdoherflache. 


62 


THE  EARTH. 


sulas  into  the  seas  which  surround  her;  and  although  she  is  not  directly 
united  to  Australia  by  a  continuous  isthmus,  yet  the  Sunda  Isles,  "  like 
the  piles  of  a  demolished  bridge,"  stretch  across  the  sea  between  the  two 
continents.  As  regards  Australia,  both  by  its  regular  and  almost  geo- 
metrical form,  and  also  by  its  entii'e  absence  of  peninsulas,  it  evidently 
reminds  us  of  the  two  other  parts  of  the  world  which  push  their  way  far 
into  the  Southern  Ocean. 


Fig.  IC.  Mundus  tiijxirtitus. 

Finally,  if  we  consider  separately  the  Old  World,  or  eastern  group  of 
continents,  we  may  recognize  a  quadripartite  division,  or  the  separation 
of  the  land  into  four  parts  arranged  two  by  two  on  the  north  and  south 
of  the  equator.  This  is  the  idea  that  was  taught  by  most  of  the  ancients, 
whidfc  also  induced  them  to  give  to  the  world  then  known  the  name  of 
Terra  quadrijida.*  Others,  no  less  following  certain  systematic  concep- 
tions, fancied  that  the  land  that  had  emerged  from  the  deep  was  shaped 
like  an  egg,  and  composed  of  three  portions,  surrounding  the  sacred  tem- 
ple of  Delphi,  "  the  umbilicus  of  the  world." 

Thus,  in  the  external  form  of  continents,  we  find  two  quite  distinct 
laws  in  action ;  one,  according  to  which  they  are  arranged  in  circles  ob- 
liquely to  the  equator,  the  other  which  distributes  them  in  three  lines  par- 
allel to  the  meridian.  To  this  complication  is  due  the  apparent  irregular- 
ity of  the  double  continents  in  the  Old  World,  for  there  the  two  axes  of 
formation  cross,  and  consequently  there,  too,  is  produced  a  great  diversity 
in  the  relief  of  the  land.  The  mutual  resemblances  and  contrast  exhibited 
by  the  two  halves  of  the  world  can,  however,  be  perfectly  well  explained 
if  we  connect  them  with  one  or  the  other  of  these  two  orders  of  facts. 
If  we  look  upon  the  land  as  forming  three  parallel  double  continents,  we 
must  then  be  struck  with  the  similarity  which  they  mutually  present 
both  as  a  whole  and  in  details;  if,  on  the  contrary,  we  admit  the  usual 
division  of  the  continental  masses  into  two  worlds,  we  discern  the  reason 
of  the  contrasts,  which  are  only  another  kind  of  resemblance.  In  this 
way  we  may  explain  the  variety  in  the  forms  of  the  continent  of  Europe, 
by  looking  upon  it  either  as  the  half  of  two  twin  continents  parallel  to 
the  two  Americas,  or  as  a  great  Asiatic  peninsula,  forming  a  portion  of 
the  immense  ring  of  land  which  extends  round  the  ocean.     Just  as  in  a 

♦  Joachim  Ldewel,  Pytheas  de  Marseille. 


EUP 


Drawn  by  A.  Vuillemin. 


PI    VI 


»s      So       33      40       4i        io        ii         60  es 


Kn*4   W  Irl-.ri 


CHAINS  OF  THE  HDWU-KUTCH.  g3 

t 
woven  fabric,  we  can  discern  both  the  warp  and  the  woof  in  the  marvel- 
ous texture  of  the  earth's  surface. 

The  principal  feature  in  the  relief  of  the  Old  World  is  the  enormous 
elevation  of  the  land  near  the  centre  of  Asia,  at  the  intersection  of  the 
lofty  chains  of  the  Hindu-Kutch,  in  that  region*of  grandeur  to  which  the 
epithet  "  the  roof  of  the  world  "  has  been  justly  given.  This  elevated 
spot,  round  which  radiate  the  Himalaya,  the  Karakorura,  the  Kuenlun,  the 
Thian-Chan,  the  Soliraan-Dagh,  and  other  chains  of  mountains,  is,  in  fact, 
the  point  of  the  earth  at  which  the  two  continental  axes  cross  one  anoth- 
er, one  tending  from  the  north  to  the  south,  the  other  from  the  southwest 
to  the  northeast,  parallel  to  the  outline  of  the  Pacific.  At  their  meet- 
ing-point the  two  terrestrial  waves  overlap  one  another,  just  as  two  bil- 
lows coming  together  in  the  open  sea  from  two  different  points  of  the 
horizon.  There,  at  the  intersection  of  the  axes,  stands  the  real  apex  of 
the  earth,  the  orographical  centre  of  continents ;  there,  too,  we  find,  was 
the  centre  of  dispersion  of  the  Aryan  nations.  By  a  remarkable  contrast, 
at  the  exact  antipodes  of  this  region  of  elevated  plains  and  lofty  mount- 
ains, we  find  those  broad  tracts  of  the  Pacific  which  are  most  destitute  of 
islands;  and  there,  too,  are  probably  situated  the  deepest  profundities  of 
the  ocean. 


(J4  THE  EAJtTH. 


CHAPTER  IX. 

PRINCIPAL     ANALOGIES    BETWEEN    CONTINENTS. — PYRAMID    FORM    OF    POR- 
TIONS   OF  THE    WORLD. — SLOPES    AND    DECLIVITIES. CLOSED    BASINS    OF 

EACH  CONTINENT. — SOUTHERN  PENINSULAS  IN  EACH  GROUP  OF  CONTI- 
NENTS.— HYPOTHESIS  OF  PERIODICAL  DELUGES. — RHYTHMICAL  ARRANGE- 
MENT OF  PENINSULAS. 

Every  continent,  considered  by  itself,  may  be  compared  to  a  pyramidal 
mass  having  an  enormous  base  and  a  summit  placed  far  from  the  centre 
of  its  figure.  Thus  Mont  Blanc,  the  loftiest  summit  of  the  Alps,  is  sit- 
uated at  a  comparatively  short  distance  from  the  west  and  south  coasts 
of  Europe.  The  latter,  therefore,  taken  as  a  whole,  may  be  looked  upon 
as  a  pyramid,  the  height  of  which  is  not  more  than  a  thousandth  part  of 
its  base ;  the  faces  turned  toward  Asia  and  the  Frozen  Ocean  being  four 
times  as  long,  on  the  average,  as  the  sides  which  tend  toward  the  Atlan- 
tic and  the  Mediterranean.  The  Asiatic  continent  has  for  its  apex  the 
lofty  mountains  of  the  Himalaya,  and  from  these  elevated  points  the  face 
of  the  country  inclines  in  very  difierent  gradients  toward  the  two  op- 
posite oceans :  on  one  side  the  fall  is  rapid  down  to  the  plains  and 
gulfs  of  Hindostan ;  on  the  other  side  the  descent  is  very  considerably 
longer. 

The  general  outline  of  the  relief  of  the  continent  of  Africa  is  less 
known ;  it  is,  however,  probable  that  the  mountains  Kenia  and  Kilimand- 
jaro  are  the  culminating  points  of  the  continental  polyhedron.  These 
mountains,  which  rise  very  far  from  the  centre  of  Africa,  also  exhibit  on 
one  side  a  comparatively  steep  incline,  and  on  the  other  a  very  gradual 
descent.  In  Australia  we  see  the  same  phenomena,  for  the  most  elevated 
points  of  this  continent  are  probably  to  be  found  in  New  South  Wales  at 
a  short  distance  from  the  edge  of  the  Pacific ;  from  these  mountains  to 
the  Indian  Ocean  the  distance  is  at  least  six  times  as  great. 

The  two  Americas,  also,  may  likewise  be  considered  as  two  solid  bod- 
ies having  their  culminating  points  far  distant  from  the  centre  of  the 
figure — one  at  Orizaba,  or  Popocatepetl,  the  other  in  the  group  of  the 
Bolivian  mountains.  In  spite  of  the  varied  outlines  of  relief  whicl*  con- 
tinents exhibit,  in  spite,  too,  of  the  basins  and  depressions  in  their  surface, 
there  are  but  few  localities  where  the  ground  shows  any  hollows  lower 
than  the  level  of  the  sea ;  and  these  hollows,  such  as  the  neighborhood 
of  the  Caspian  and  the  valley  of  the  Dead  Sea,  are  situated  precisely  on 
the  respective  confines  of  two  continents,  Europe  and  Asia,  and  Asia  and 
Africa.  Even  the  depressions  of  the  Algerian  Sahara,  the  surface  of 
which  is  in  many  places  lower  than  the  Mediterranean,  are  the  bed  of  the 


PYRAMID  FORMS.  §5 

ancient  sea  which  once  separated  the  real  Africa  from  the  districts  of  the 
Atlas. 

Another  great  feature  of  resemblance  between  the  various  continental 
masses  is  that  eacli  of  them  contains  one  or  more  closed  basins,  where  a 
receptacle  is  found  for  the  water-courses  which  can  not  flow  to  the  outer 
bide  of  the  continent ;  these  concavities  having  their  own  peculiar  system 
of  lakes  and  rivers,  are,  as  it  were,  so  many  worlds  by  themselves.  The 
Asiatic  continent,  the  largest  of  all,  and  that  in  which  the  sui)posed  cen- 
tre is  most  distant  from  the  sea,  is  the  continent  in  which  the  inland  hy- 
drographical  basins  are  of  the  greatest  extent.  They  comprehend  nearly 
the  whole  area  of  the  high  plateaux  of  Tartary  and  Mongolia,  namely,  the 
))asins  of  Lob-Xor,  Tengri-Nor,  Koko-Nor,  and  Oubsa-Nor ;  and  on  the 
west  of  the  great  mountain  chains  of  Central  Asia  they  also  embrace  the 
plateau  of  Iran,  the  basin  of  Balkach,  and  also  the  basins  of  the  sea  of 
Aral  and  the  lakes  of  Van  and  Ourmiah.  By  the  depression  of  the  Cas- 
pian, the  Asiatic  series  of  lakes  without  outlet  is  connected  with  the  Eu- 
ropean system,  which  extends  to  the  very  centre  of  Russia,  to  the  sources 
of  the  Kama  and  the  Volga.  The  whole  of  this  region,  the  waters  of 
which,  from  the  hills  of  the  Russian  Valdai  to  the  plateaux  of  Mongolia, 
tind  no  outlet  in  the  direction  of  the  sea,  embraces  an  area  at  least  as  ex- 
tensive as  that  of  Europe.  The  two  continents  of  America  likewise  have 
their  isolated  systems  of  lakes  and  rivers  occupying  a  corresponding  posi- 
tion— one  in  the  "Great  Basin,"  between  the  Rocky  Mountains  and  the 
Sierra  Nevada  of  California,  the  other  on  the  plateau  of  Titicaca,  between 
the  chain  df  the  Andes  and  the  Cordi^ras  properly  so  called.  Africa, 
too,  has  several  basins  without  outlet,  tne  principal  one  being  that  of  the 
Lake  Tchad,  situated  in  the  centre  of  the  continent.  Finally,  even  Aus- 
tralia, in  spite  of  its  comparatively  small  extent,  has  its  lakes,  Torrens, 
Gairdner,  and  others,  which  do  not  communicate  with  the  sea.* 

As  Bacon  formerly  remarked,  the  three  groups  of  continents  exhibit 
also  a  singular  resemblance  to  one  another  in  the  pyramidal  form  of  their 
terminal  points  in  the  direction  of  the  Antarctic  Ocean.  These  three 
southern  peninsulas  do  not  advance  to  an  equal  distance  into  the  sea,  as 
they  reach  respectively  to  36,  44,  and  56  degrees  of  south  latitude,  but 
they  may  be  connected  by  an  ideal  circle,  inclined  10  degrees  to  the 
South  Pole.f  The  distances  between  the  extremities  of  the  three  conti- 
nents are  not  very  far  from  equal  on  the  terrestrial  periphery,  as  the 
tracts  of  ocean  between  the  Cape  of  Good  Hope  and  Cape  Horn,  Cape 
Horn  and  Tasmania,  Tasmania  and  the  South  of  Africa  are  nearly  in  the 
ratio  of  the  numbers  7,  8,  and  9. 

Each  of  these  promontories,  pushed  forward,  as  they  are,  from  the  rest 
of  the  land,  appears  to  have  been  partly  demolished  by  the  waves.  Thus 
the  extremity  of  South  America  presents  the  appearance  of  an  immense 
ruin  ;  the  tortuous  Straits  of  Magellan  separate  it  from  the  Tierra  del 
Fnego,  which  is  itself  divided  into  numerous  islets  by  a  labyrinth  of 

•  Vide  the  Map  of  the  World,  Tl.  I.  t  Jean  Reynaud,  Terre  et  del. 

£ 


66 


THE  EARTH. 


Fig.  17.  Circle  of  Jnri^llon  of  the  Continental  Points. 


channels,  and  is  guarded  on  the  south,  as  by  a  couching  lion,  by  the  for- 
midable headland  of  Cape  Horn.  At  the  southern  point  of  Africa  stands 
another  "  Cape  of  Storms,"  to  which  a  feeling  of  confidence  in  the  ap- 
proaching discovery  of  India  gave  the  name  of  the  Cape  of  Good  Hope. 
To  the  east  of  this  promontory,  which  is  connected  with  the  main  body 
of  the  continent  by  a  system  of  plateaux  and  mountains,  a  great  bank  or 
shelf  pushes  out  fer  into  the  sea ;  this  bank  is  doubtless  the  remains  of 
some  vanished  land,  and  the  force  of  the  marine  currents  still  bi-eaks  over 
it.*  The  Australian  continent,  too,  has  for  its  southern  projection  the 
steep  shore  of  Van  Dieraen's  Land ;  for,  by  its  geographical  position,  this 
island  evidently  belongs  to  Australia ;  the  error,  therefore,  of  Cook,  who 
looked  upon  Tasmania  as  nothing  but  a  promontory  of  New  Holland,  was 
more  apparent  than  real.  There  is  another  fact  which  completes  the  re- 
semblance between  the  terminal  points  of  the  three  continents  of  the  antarc- 
tic hemisphere,  namely,  that  each  of  the  seas  which  extend  to  the  east 
of  these  countries  washes  some  island  or  considerable  archipelago.  On 
the  east  of  Australia  there  is  New  Zealand ;  at  the  east  of  the  South 
American  continent  we  find  the  Falkland  archipelago ;  east  of  Africa, 
the  large  island  of  Madagascar. 

*  Houzeau,  De  la  Symetrie  des  Formes  des  Continents. 


AF 


T)rawii  by  A  Vuillemin 


HARPEP, 


PI.  Ml 


Kn0^'    W     IrhiT'J 


J".  A 


PENINSULAS.  67 

These  remarks  of  Bacon,  since  developed  by  Buffon,  Forster,  the  com- 
panion of  Cook,  and  in  modem  times  by  Steftens,  Carl  Ritter,  Arnold 
Guyot,  and  others  geographers,  have  given  rise  to  the  hypothesis  that  a 
terrible  deluge,  coming  from  the  southwest,  once  rushed  over  the  conti- 
nents of  the  southern  hemisphere,  crumbling  them  up,  dismembering  them, 
and  carrying  their  debris  over  the  northern  contments,  thus  forming  the 
long  slopes  which  incline  toward  the  Arctic  Ocean.  The  land  in  the 
north  would  thus  be  disproportionately  augmented  at  the  expense  of  the 
south,  of  which  nothing  would  be  left,  so  to  speak,  but  the  skeleton.  To 
this  great  inundation,  which  carved  out  afresh  the  great  continental 
masses,  Pallas,  the  Russian  traveler,  attributes  the  transport  of  the  innu- 
merable remains  of  mammoths  which  are  found  buried  in  the  soil  of  the 
Siberian  tundras.  This  hypothesis  has  been,  as  we  know,  adopted  since 
by  Adhemar  and  his  disciples.  In  the  opinion  of  these  geologists,  who 
recognize  the  great  agents  of  terrestrial  renovation  in  a  series  of  periodi- 
cal deluges  proceeding  alternately  from  the  north  and  south  every  10,500 
years,  the  bones  found  in  Siberia  were  brought  there  by  the  last  deluge 
but  one,  which  resulted  from  the  breaking  up  of  the  ice  at  the  south  pole. 
According  to  one  of  these  hypotheses,  the  last  dissolution  of  the  ice  came 
from  the  south  ;  according  to  the  other,  from  the  north.  It  is,  therefore, 
prudent  to  set  aside  these  contradictory  ideas  which  attribute  to  some 
cataclysm  the  peninsular  form  of  the  southern  continents.  Besides,  at  the 
present  day,  there  is  no  longer  any  doubt  that  both  the  mammoth  and 
rhmoceros  were  once  natives  of  Siberia — the  very  country  where  their 
remains  are  now  found.* 

Almost  all  the  great  peninsulas  of  the  eai-th — as  Greenland,  Kamt- 
schatka,  and  Corea,  including  even  those  which  would  suggest  a  sudden 
change  in  the  sea-level — extend  in  a  southerly  direction.  Added  to  this, 
each  of  the  three  northern  continents,  in  their  southern  articulations,  seem 
to  adopt  as  a  type  the  three  southern  continents  taken  as  a  whole ;  thus, 
each  puts  out  three  peninsulas  into  the  seas  which  bathe  its  southeni 
shores.  In  Europe,  Asia,  and  North  America  respectively,  three  groups 
of  secondary  peninsulas  correspond  to  the  three  great  promontories  of  the 
southern  world. 

In  the  Old  World  especially,  these  peninsular  articulations  are  formed 
■with  a  considerable  degree  of  regularity,  and,  so  to  speak,  of  rhythm  and 
measure  ;  in  the  different  continents,  they  exhibit  the  most  striking  anal- 
ogies. Arabia,  in  the  proud  and  simple  beauty  of  its  outline,  recalls  to 
mind  the  elegant  and  yet  majestic  form  of -Spain ;  Hindostan,  in  the  gen- 
tle undulations  of  its  banks  and  the  roundness  of  its  bays,  corresponds  to 
Italy ;  India  beyond  the  Ganges,  by  its  numerous  indentations  and  the 
enormous  development  of  its  coasts,  seems  the  counterpart  of  Greece — 
that  beautiful  country,  the  outline  of  which  has  been  so  justly  compared 
to  that  of  a  mulberry-leaf.  In  both  continents,  the  peninsulas  become 
more  and  more  articulated,  and  more  and  more,  as  it  were,  endowed  with 
*  Die  neuesten  Arbeiten  iiber  das  Mammuth,  Mittheilungen  von  Petermanit,  ix.,  18C6. 


gg  THE  EARTH. 

vitality  as  we  proceed  from  west  to  east.  The  Mediterranean  peninsulas 
particularly  present  the  remarkable  phenomenon  that  the  variety  of  out- 
line is  greater  in  proportion  to  their  nearness  to  the  rising  sun.  The  nu- 
merous bays  which  hollow  out  the  coast  of  Spain  all  along  the  Mediterra- 
nean shore  are  developed  in  regular  arcs  of  a  circle  equal  on  the  average 
to  a  quarter  of  its  circumference.  The  Italian  gulfs — those  of  Genoa,  Na- 
ples, and  Salerno — are  spread  out  in  perfect  semicircles  round  the  coast 
of  the  peninsula ;  while  the  gulfs  of  Greece  form  very  deep  indentations 
into  the  land,  and,  like  the  Gulf  of  Lepanto,  might  be  called  Mediterra- 
neans in  miniature. 

It  must  also  be  remarked  that  on  the  east  of  the  somewhat  severely- 
designed  coasts  of  the  analogous  peninsulas  of  Spain  and  Arabia,  the  isl- 
ands are  but  few  and  of  small  importance.  Italy  and  India,  on  the  con- 
trary, the  forms  of  which  are  richer,  have  each  their  large  island,  and, 
with  their  southern  extremities,  almost  touch  Sicily  and  Ceylon  respect- 
ively. With  regard  to  Greece  and  the  Transgangetic  peninsula,  the  seas 
which  bathe  their  eastern  coasts  are  dotted  over  with  innumerable  islands 
and  islets,  like  a  brood  of  young  birds  nestling  under  the  wing  of  their 
mother.  The  two  other  eastern  peninsulas,  which  are  also  thrown  off  by 
the  great  Asiatic  continent,  ai"e  each  of  them  likewise  accompanied  by  an 
archipelago. 

The  three  southern  peninsulas  of  North  America  do  not  exhibit  the 
same  regularity  in  their  aspect  as  those  of  Europe  and  Asia.  In  conform- 
ity with  the  somewhat  narrow  and  elongated  form  of  the  continent  itself, 
two  of  these  peninsulas — Florida  and  Lower  California — seem  attenuated 
in  comparison  with  the  analogous  portions  of  the  Old  World.  The  other 
peninsular  appendage,  which,  being  placed  in  the  very  axis  of  the  New 
World,  is  much  more  developed,  is  none  other  than  the  isthmus  of  Cen- 
tral America,  now  modified  and  distorted.  In  fact,  a  simple  depression 
of  the  ground  of  about  one  hundred  feet  is  all  that  is  needed  in  order  that 
the  Pacific  and  the  Caribbean  Sea  should  unite  their  waters  between  the 
two  American  continents ;  besides,  it  appears  that,  at  a  recent  geological 
epoch,  a  channel,  at  least  thirty-seven  miles  wide,  connected  the  two  seas 
across  the  plain  which  is  now  filled  with  a  lava  deposit,  and  is  command- 
ed on  one  side  by  the  Sierra  de  Maria  Enrico,  and  on  the  other  by  the 
Sierra  Trinidad.*  A  single  feature  of  the  earth's  relief  may  at  the  same 
time  fulfill  several  functions :  thus,  exactly  at  the  antipodes  of  Central 
America,  the  Sunda  Islands  are  also  an  isthmus  between  the  two  conti- 
nents of  Asia  and  New  Holland. 

There  are  immerous  other  analogies  between  the  different  parts  of  the 
world  which  we  might  also  mention ;  but  most  of  them  may  be  referred 
to  those  we  have  named,  or  else  they  belong  more  to  the  province  of  ge- 
ology propei'ly  so  called. 

*  Moritz  Wagner,  Mittheilungen  von  Petermann,  1861. 


CONTRACTS  m  AIUEA  AND  FORM. 


CHAPTER  X. 

NUMEROUS  INDENTATIONS  OF  THE  NORTHERN   CONTINENT. HEAVINESS    OF 

FORM  IN  THE    SOUTHERN  CONTINENTS. — INEQUALITY  OP  SIZE  IN  THE  CON- 
TINENTS OP  THE  OLD  WORLD. — EXTENT  OP  COAST-LINE  IN  INVERSE  RATIO 

TO  THE  AREA  OP  LAND. CONTRASTS  BETWEEN  THE  OLD  WORLD  AND  THE 

NEW. — THE   TRANSVERSE  POSITION   OP  THE   AXES   OP   AMERICA   AND   THE 

OLD    WORLD. CONTRASTS    OP    CLIMATE    IN    THE    VARIOUS    CONTINENTS  : 

NORTH  AND  SOUTH,  EAST  AND  WEST. 

The  contrast  between  the  shapes  of  the  various  continental  shores  is 
one  which  is  very  easily  verified.  North  America,  Europe,  and  Asia 
have  a  very  considerable  extent  of  coast-line  in  comparison  with  their 
bulk.  They  are  penetrated  for  long  distances  by  deep  gulfs  and  inland 
seas,  and  their  outline  is  rugged  with  promontories ;  it  might  be  said 
that  the  organization  of  these  continental  masses  bears  some  resemblance 
to  an  articulated  body  and  its  limbs.  South  America,  Africa,  and  Aus- 
tralia seem,  on  the  other  hand,  to  enjoy  but  a  rudimentary  conformation ; 
their  contour  is  almost  geometrically  regular  and  simple,  and  their  bays 
and  gulfs  are  so  slightly  indented  into  the  land,  that  the  regular  line  of 
the  coast  is  scarcely  altered  ;  there  is,  too,  an  almost  complete  deficiency 
in  promontories  of  a  peninsular  form.  In  the  great  scale  of  terrestrial  or- 
ganization, these  continents  present  an  inferior  phase  of  life.  Neverthe- 
less, this  heaviness  of  contour  and  deficiency  of  peninsulas  are  in  great 
part  compensated  for  by  the  more  oceanic  position  of  the  southern  conti- 
nents and  the  prevalence  in  them  of  a  tropical  climate.  In  fact,  under 
the  tropics,  the  air,  being  much  warmer,  is  saturated  by  a  larger  quantity 
of  moisture  ;  and  the  atmospheric  currents,  being  more  rapid  and  regular, 
carry  the  sea-breezes  across  much  wider  areas.  Thanks  to  the  tropical 
rains,  trade-winds,  and  hurricanes,  the  enormous  masses  of  South  America 
and  even  Africa  are  as  much  exposed  to  oceanic  influences  as  other  parts  of 
the  world  which  are  more  deeply  indented  by  gulfs  and  bays.  The  three 
northern  continents,  on  the. contrary,  the  shores  of  which  are  so  cut  into 
and  pierced  in  every  direction,  owe  to  their  inland  seas  the  ability  (as  re- 
gards a  considerable  portion  of  their  surface)  of  imbibing  those  aqueous 
vapors  without  which  they  would  be  nothing  but  immense  deserts. 

The  area  of  the  continents  is  a  fact  no  less  important  than  their  form, 
and  the  contrasts  afforded  in  this  respect  are  also  not  a  little  striking. 
While  the  two  halves  of  America  are  almost  equal  in  extent,  the  four 
continents  of  the  Old  World  differ  much  in  the  size  of  their  respective 
areas.  Asia,  by  herself,  includes  a  larger  surface  of  land  than  the  two 
Americas  together.     Europe,  pushed  out  into  the  ocean  as  a  mere  Asiatic 


70  THE  EARTH. 

peninsula,  is  foui*  or  five  times  smaller  than  the  enormous  mass  with  which 
she  is  connected.  In  the  south,  the  surface  of  Africa  is  three  times  as 
great  as  that  of  Europe,  while  Australia,  compared  with  its  northern 
neighbor,  the  area  of  which  is  six  times  bigger,  scarcely  deserves  more 
than  the  name  of  a  great  island.  It  must,  however,  be  remarked  that,  by 
a  very  curious  phenomenon  of  compensation,  the  two  halves  of  each  con- 
tinental pair  are  arranged  so  as  to  balance  on  the  terrestrial  sphere.  In 
the  western  pair,  Africa,  which  is  the  preponderant  portion,  lies  to  the 
south,  and  the  smaller  Europe  extends  to  the  north.  In  the  eastern  pair, 
it  is  just  the  reverse:  on  the  north  is  the  great  continent  of  Asia,  and  on 
the  south  the  region  of  New  Holland,  which  would  correspond  with  Eu- 
rope. 

AREA  OF  CONTINENTS. 

FIRST    PAIR.  • 

North  America 7,953,315  square  miles. 

South  America 6,949,674       "        " 

SECOND   FAIR. 

Europe 3,822,320       "        " 

Africa 11,244,958       "        '/ 

THIRD   PAIR. 

Asia 16,771,879       "        " 

Australia 2,972,916       "        " 

The  continents  may  also  be  compared  by  pointing  out  the  respective 
distances  of  their  ideal  centres  from  the  nearest  point  on  the  shore  of  the 
ocean. 

CONTINENTAL  RADII. 

FIRST    PAIR. 

North  America 1087  miles. 

South  America 931     " 

* 

SECOND   PAIR. 

Europe 478  miles. 

Africa 1118     " 

*  THIRD    PAIR. 

Asia 1491     " 

Australia 615      " 

This  great  inequality  in  the  size  of  the  continents  might  furnish  cause  for 
surprise,  wei-e  we  not  well  aware  that,  according  to  the  beautiful  law  pro- 
pounded by  Geoffroy  Saint-Hilaire,  no  function  can  be  unduly  developed 
except  at  the  expense  of  some  other  function.  Europe  is  small,  it  is  true ; 
but  what  an  opulence  of  coast-line  does  she  enjoy  !  What  profusion  of 
gulfs  and  peninsulas  diversify  her  outline,  how  many  islands  and  islets 
there  are  in  her  seas  !  In  Europe,  land  and  water  are  arranged  in  alter- 
nate layers  as  if  to  form  an  immense  electrical  battery,  where  the  acid, 
sheets  of  metal,  and  conducting  wires  are  replaced  by  seas,  land,  and  aeri- 
al currents.  Europe  is  so  variously  articulated  that  she  enjoys  a  more 
considerable  extent  of  coast-line  than  either  South  America  or  Africa  it- 


/♦Tfxrj  /•<  J^  y>!i/lemin 


HARFEB    ^^.  BROT? 


PL  .VIII 


VvT    \'':  ^  p  I-; 


EXTENT  OF  SEA- COAST.  7X 

self,  both  of  which  fill  so  much  greater  an  area.  Australia  at  first  sight 
appears,  from  its  solid  form,  to  constitute  a  modification  of  the  law  ac- 
cording to  which  the  smallest  continental  masses  are  the  most  highly 
organized.  But  Australia  must  not  be  looked  upon  as  an  isolated  body; 
we  are  bound  to  take  into  accouut  the  elongated  isthmus  of  islands  and 
islets  which  connects  it  with  Ind^Phina.  Along  this  former  isthmus  are 
scattered  numerous  archipelagos,  presenting  an  almost  incalculable  devel- 
opment of  coast-line,  and  consequently  possessing  all  the  advantages  of 
climate,  richness,  and  fertility  which  are  aflTorded  by  a  maritime  position ; 
there,  too,  more  than  in  any  other  part  of  the  world,  the  magnificence  of 
terrestrial  vitality  is  displayed  in  the  splendor  and  variety  of  its  pro- 
ductions. 

The  following  tables,  which  give  in  miles  the  absolute  and  relative 
length  of  the  sea-coast  of  each  continent,  are  therefore  necessarily  incom- 
plete. How  shall  we  separate  from  Europe  England,  Ireland,  Sicily,  and 
the  Isles  of  Greece — all  of  them  countries  which  have  played  so  important 
a  part  in  the  history  of  civilization?  How  can  we  neglect,  in  the  New 
World,  the  West  India  Islands,  and  the  islands  lying  to  the  east  of  the 
continent  of  Asia — the  Moluccas,  the  Sunda  Archipelago,  and  Japan  ? 
< 

EXTENT  OF  SEA-COAST. 

FIRST    PAIR. 

North  America 29,969  miles. 

South  America 16,012      " 

SECOND   PAIR. 

Europe 19,825      " 

Africa 12,561      " 

THIRD    PAIR. 

Asia 35,886      " 

Australia 8,947      " 

PROPORTION  OF  SEA-COAST  TO  SURFACE. 

FIRST   PAIR. 

North  America 1  mile  to  265  square  miles. 

South  America 1    "     "434       "        " 

SECOND    PAIR. 

Europe 1    "     "  i;)2      "        " 

Africa 1    "     "  895       "        " 

THIRD   PAIR. 

Asia 1    "     "  469       "         " 

Australia 1    "     "  332       "         " 

By  taking  account  of  the  principal  islands — Great  Britain,  Ireland,  Sar- 
dinia, Sicily,  and  several  others — the  total  extent  of  the  European  coast- 
line may  be  estimated  at  26,716  miles,  which  will  give  one  mile  for  143 
square  miles  of  surface. 

In  the  two  continents  of  the  New  World,  the  plateaux  and  the  plains 
show  a  surface  nearly  equal  in  extent,  and,  in  this  respect,  present  a  har- 


72  THE  EARTH. 

mony  which  does  not  exist  in  the  Old  World.  All  the  western  countries 
of  North  America,  as  well  as  a  great  part  of  its  eastern  regions,  consist  of 
plateaux,  some  level  and  others  commanded  by  mountain  chains.  The 
plains  which  extend  between  these  two  systems  of  elevated  ground,  and 
embrace  the  fluviatile  basins  of  British  America  and  of  the  Mississippi 
and  Missouri,  are  equal  in  surface  to  ^p  higher  regions  along  the  edges 
of  the  two  coasts.  In  South  America  the  plains  are  comparatively  more 
extensive.  Nevertheless,  if  to  the  chain  of  the  Andes  and  their  subsidi- 
aries, we  add  all  the  Colombian  plateaux,  those  of  Peru  and  Bolivia,  the 
groups  of  Famatina,  Aconquija,  and  Cordova,  the  sierras  of  the  Guianas, 
the  chains  of  the  Brazilian  coast  and  of  Minas  Geraes,  the  gigantic  steppes 
of  Patagonia  between  the  ridges  of  the  Andes  and  the  Atlantic  coast,  we 
shall  find  that  the  balance  is  kept  pretty  equal  between  the  high  and  the 
low  lands  of  this  part  of  the  world.  According  to  Humboldt,  whose  fig- 
ures, however,  should  be  carefully  criticised  with  all  the  means  afforded 
us  by  our  increasingly  exact  acquaintance  with  the  outline  of  the  terres- 
trial relief,  the  mean  elevation  of  North  America  is  747  feet,  and  that 
of  South  America  would  'attain  to  1149  feet. 

The  continents  of  the  Old  World  do  not  afford  an  equal  hannony  in 
the  general  configuration  of  their  elevation.  Asia,  taken  as  a  whole,  is  a 
vast  system  of  plateaux,  extending  from  the  headlands  of  Asia  Minor  to 
those  of  the  Corea,  and  from  the  shores  of  Beloochistan  to  those  of  the 
province  of  Ochotsk.  The  central  region  of  Asia,  surrounded  by  the 
highest  mountains  in  the  world,  is  the  most  elevated  district  existing  in 
any  of  the  continents,  and  in  some  places  attains  the  mean  height  of  9000, 
12,000,  and  15,000  feet.  The  total  area  of  the  Asiatic  plateaux  is  esti- 
mated by  Humboldt  at  five-sevenths  of  this  part  of  the  world ;  Mesopo- 
tamia, the  plains  of  the  Ganges  and  of  the  Indus,  China  proper,  and  the 
Siberian  tundras  make  up  the  other  two-sevenths  of  the  continent.  As 
if  to  make  up  for  this,  Australia  is  comparatively  very  deficient  in  pla- 
teaux and  mountain  chains ;  of  all  the  divisions  of  the  earth  this  is  the 
one  which  exhibits  the  least  amount  of  prominence  above  the  ocean  level. 
The  mean  elevation  can  as  yet  be  given  but  very  hypothetically,  as  a 
great  part  of  the  regions  of  the  interior  is  still  unknown ;  but  this  conti- 
nent must  present  about  a  third  of  the  elevation  of  Asia — the  latter  be- 
ing approximately  estimated  by  Humboldt  at  1162  feet. 

Europe  being  situated,  in  the  Old-World  group,  in  a  diagonal  line  as 
regards  Australia,  affords,  like  the  latter  continent,  a  great  prejionderance 
of  plains  and  plateaux.  Almost  the  whole  of  Eastern  Europe  is  a  level 
country ;  and  this  district — a  great  part  of  which  is  cultivated,  although 
here  and  there  covered  with  turf  and  heath — extends  through  Poland  and 
Prussia  as  far  as  the  frontiers  of  France  and  Belgium.  Over  this  im- 
mense area,  the  level  of  the  ground  is  so  uniform  that  from  Nijni-Novo- 
gorod  to  Cologne,  a  distance  of  2454  miles,  there  is  not  a  single  railway 
tunnel.  In  Western  Europe,  which,  in  a  historical  point  of  view,  is  the 
real  Europe,  the  more  elevated  regions  are,  it  is  true,  very  numerous ; 


^ 


AUSTRALIA  AND 


tTa*vi,   by    A  Vuiilemin . 


HARPER   ^  ERi 


ADJACENT  ARCHIPELAGO 


PL.  IX. 


Knfe'^ty  Erhard. 


Rs   }jy^w  yoPK 


PLATEAUX.  73 

but  most  of  them  amount  to  mere  mountain  chains,  on  each  side  of  which 
extend  considerable  tracts  of  level  country.  The  only  plateaux  of  any 
notable  importance  in  the  general  configuration  of  the  continent  are  those 
of  the  Iberian  peninsula,  Suabia,  and  Turkey ;  all  three,  with  a  kind  of 
rhythm,  abut  on  mountain  chains,  the  other  faces  of  which  command  hor- 
izontal flats  of  alluvium.  On  the  north  of  the  Pyrenees  and  the  Spanish 
plateau  lie  the  plains  of  the  Garonne  and  Languedoc ;  on  the  south  of 
the  Bavarian  plateau  and  the  rampart  of  the  Alps  stretch  the  plains  of 
Lombardy  and  Piedmont,  forming  a  continuation  of  the  level  surface  of 
the  Adriatic  Sea;  finally,  the  low-lying  lands  of  the  Danube  are  separated 
from  the  plateaux  of  Turkey  by  the  Balkan  chain,  which  extends  in  a  line 
almost  parallel  to  that  of  the  Pyrenees.* 

On  account  of  the  plateaux  existing  in  Europe  being  so  few,  the  mean 
elevation  of  this  continent  \s  not  much  more  than  half  that  of  Asia ;  ac- 
cording to  Humboldt  it  is  about  672  feet.  With  regard  to  Africa,  we 
need  hardly  say  that  it  is  impossible  to  fix  the  mean  elevation  with  any 
certainty ;  but  modern  travelers  who  have  penetrated  into  the  interior 
of  this  division  of  the  world  have  seen  enough  of  it*to  warrant  them  in 
stating  that  Africa  is  very  similar  to  Asia  in  respect  to  the  elevation  of 
the  land.  With  the  exception  of  Egypt,  the  plains  of  the  Niger,  some  por- 
tions of  the  sea-coast,  and  districts  of  the  Sahara,  which  were  once  covered 
by  the  sea,  the  continent  is  entirely  composed  of  plateaux,  most  of  which 
abut  on  lofty  mountain  chains.  The  laic  of  diagonals^  which  is  followed  in 
the  respective  dimensions  of  the  four  continents  of  the  Old  World,  is  found 
also  to  hold  good  as  regards  their  general  configuration.  Asia  and  Africa, 
the  two  continents  in  which  the  plateaux  predominate,  are  placed  diagon- 
ally to  Europe  and  Australia,  in  which  the  plains  are  the  most  extensive.f 

Another  great  contrast  between  the  Old  and  New  Worlds  is  one  that 
is  exhibited  in  the  central  portions  of  these  groups.  Between  the  two 
Americas  stretches  a  sea  of  an  almost  circular  shape,  surrounded  on  all 
sides  by  a  belt  of  islands  and  continental  shore.  The  centre  of  the  Old 
World,  on  the  contrary,  is  occupied  by  the  plains  of  Mesopotamia,  and 
high  ground  toward  which  tend  several  seas  in  an  oblique  direction. 
The  Persian  Gulf,  the  Red  Sea,  the  Mediterranean,  the  Euxine,  and  the 
Caspian  surround  this  central  spot  of  the  Eastern  continents,  and  approach 
the  pentagonal  mass  obliquely  at  almost  symmetrical  intervals.  Looking 
at  the  form  and  direction  of  these  seas,  it  seems  as  if  the  region  which 
they  circumscribe  had  experienced  a  kind  of  wrench,  as  if  it  had  been 
drawn  into  some  vast  eddy. 

Another  very  remarkable  phenomenon  of  equilibration  is  exhibited  in 
the  fact  that  the  highest  mountains  of  each  of  the  two  halves  of  the  world 
are  situated  in  opposite  hemispheres,  but  at  an  equal  distance  from  the 
equator.  Near  one  of  the  tropics  rise  the  lofty  Himalaya  and  the  other 
great  mountain  groups  of  Asia ;  close  to  the  other  tropic  stand  the  Boli- 
vian and  Chilian  Andes. 

♦  Carl  Ritter,  Europa.  t  Guyot,  Earth  and  Man. 


74  THE  EARTH. 

There  is  another  difference  between  the  various  divisions  of  the  world 
which  we  must  call  attention  to.  In  jpursuance  of  the  annular  distribu- 
tion of  the  continents  round  the  great  ocean,  the  western  coasts  of  Europe 
and  Africa  correspond  with  the  eastern  coast  of  the  New  World,  and  not 
with  the  western,  as  analogy  would  seem  to  dictate.  On  the  north,  Scan- 
dinavia forms  a  counterpoise  to  Greenland.  More  to  the  south,  the  two 
shores  which  front  each  other  across  the  North  Atlantic  bear  a  striking 
resemblance  to  each  other  in  their  numerous  indentations,  their  deeply- 
penetrating  gulfs,  their  peninsulas,  and  their  islands,  while  between  the 
coasts  of  Europe  and  those  of  California  and  British  Columbia  there  is  no 
symmetry  whatever.  With  regard  to  Africa,  several  geographers,  includ- 
ing Humboldt  himself,  have  thought  that  this  continent  and  South  Amer- 
ica had  their  corresponding  coasts  set  in  the  same  direction.  But  this  is 
not  the  case ;  these  two  divisions  of  the  wor^d  present  the  same  mutual 
contrast  as  the  two  hands  of  a  man.  There  is  symmetry,  but  not  equal- 
ity. In  fact,  the  highest  plateaux  and  the  loftiest  mountains  in  Africa 
rise  at  the  east  side  of  this  continent,  while  the  chain  of  the  Andes  com- 
mands the  western  'Shores  of  South  America.  The  most  important  Afri- 
can rivers — the  Orange  River,  the  Congo,  the  Niger,  and  even  the  Nile — 
empty  their  waters,  either  directly  or  indirectly,  into  the  basin  of  the  At- 
lantic, into  which  are  also  discharged  the  immense  rivers  of  the  Colombian 
continent — the  La  Plata,  the  Amazon,  the  Orinoco,  and  the  Magdalena. 
In  the  same  way,  the  Saharan  deserts,  which  tend  toward  the  Atlantic 
Ocean,  answer  to  the  llanos  of  Venezuela  and  the  pampas  of  La  Plata ;  the 
latter  being  likewise  inclined  toward  the  same  oceanic  basin.  Finally, 
the  two  isthmuses  of  Suez  and  Panama,  each  at  the  angle  of  their  respect- 
ive continents,  occupy  a  corresponding  though  opposite  position.  Sim- 
ilarly, Cape  Verd  must  be  considered  as  the  corresponding  point  to  the 
Brazilian  promontory  of  St.  Roch,  and  the  Gulf  of  Guinea  is  represented 
on  the  other  side  of  the  ocean  by  the  wide  semicircle  of  coast  which  opens 
out  on  the  south  of  Brazil.  Even  in  the  bed  of  the  sea  the  symmetry 
still  prevails,  since  an  upheaval  of  4500  yards  would  have  the  effect  of 
calling  forth  in  the  midst  of  the  Atlantic  a  long  strip  of  land  separated 
from  Europe  and  the  New  World  by  two  parallel  channels. 

In  each  of  the  two  groups  of  continents,  the  steep  and  gentle  inclines 
are  distributed  respectively  in  contrary  directions.  In  Europe,  Africa, 
and  Asia,  the  most  elongated  incline  of  the  land  tends  in  a  northerly  and 
westerly  direction  toward  the  Atlantic  Ocean  and  the  Frozen  Sea.  In 
the  New  World  the  more  gradual  slopes  of  the  continent  likewise  de- 
scend toward  the  Atlantic  coast — that  is,  in  an  eastward  direction.  We 
thus  have  a  contrast  which  is  also  a  harmony :  it  is  as  if  the  faces  of  the 
two  worlds  were  turned  one  to  the  other,  thus  rendering  more  easy  of  ac- 
cess their  coasts,  their  plains,  their  rivers,  and  all  the  regions  suitable  for 
the  abode  of  man. 

Another  contrast,  which  is  perhaps  the  most  important  of  all  in  the  his- 
tory of  mankind,  is  that  exhibited  by  the  transverse  position  of  the  two 


CONTRASTS  OF  CLIltATE.  75 

groups  of  continents  in  reference  to  each  other.  The  countries  of  the  Old 
World,  which  show  the  richest  luxuriance  and  the  most  exuberant  vital- 
ity, lie  between  the  Straits  of  Gibraltar  and  the  Archipelago  of  Japan,  and 
extend  from  west  to  east  in  a  line  parallel  to  the  equator;  the  New 
World,  on  the  other  hand,  stretches  from  north  to  south,  in  the  direction 
of  the  meridian.  Thus,  the  double  continent  is  set  right  athwart  the 
course  followed  by  the  winds  and  the  currents,  and  across  the  path  taken 
by  the  human  race  in  making  their  way  from  the  other  group  of  coun- 
tries ;  it,  therefore,  receives  and  develops  the  germs  of  life,  the  elabora- 
tion of  which  had  commenced  on  the  other  side  of  the  sea.  This  trans- 
verse position  of  America  in  respect  to  the  Old  World  is  one  of  the  prin- 
cipal features  of  the  planetary  relief,  and  one  also  which  exercises  a  de- 
cisive influence  on  the  future  of  the  whole  human  race. 

Finally,  it  must  not  be  forgotten  that  the  principal  contrasts  of  the  con- 
tinental masses  proceed  naturally  from  all  the  modifications  produced  by 
the  difference  of  longitude  and  latitude.  These  contrasts  are  those  of 
climate,  and  their  real  cause  is  to  be  found  in  the  form  of  the  earth  and 
its  movements  round  the  sun. 

Thus,  the  astronomical  contrast  between  the  north  and  the  south 
divijles  distinctly  the  different  parts  of  the  world  into  two  separate 
groups.  Almost  the  whole  extent  of"  the  three  northern  continents  be- 
long to  the  temperate  zone,  and  it  is  only  their  most  advanced  peninsulas  ■ 
which  are  pushed  forward — on  one  side  into  the  frigid,  and  on  the  other 
into  the  torrid,  zone.  With  regard  to  the  three  southern  continents,  they 
present  their  chief  development  between  the  tropics  or  in  the  south  tem- 
perate zone.  They  receive  the  greatest  amount  of  annual  heat,  and  con- 
sequently become  the  theatre  of  the  most  remai'kable  phenomena  of  plan- 
etary vitality.  There  the  cross  action  of  the  winds  and  rains  between 
the  two  hemispheres  takes  place,  and  hurricanes  take  their  rise ;  there, 
immense  deserts  extend  over  vast  areas;  there,  too,  vegetation  manifests 
all  its  productive  energy,  and  the  terrestrial  Fauna  attains  its  greatest 
force  and  its  highest  beauty. 

The  contrast  between  the  east  and  the  west  is  also  of  the  highest  im- 
portance in  each  group  of  continents ;  for  all  the  train  of  climatic  phe- 
nomena which  accompanies  the  sun  in  its  apparent  course  round  the 
earth  does  not  uniformly  follow  the  latitude  in  a  parallel  line  to  the  equa- 
tor. In  consequence  of  the  unequal  division  of  land  and  sea,  there  is  a 
modification  in  the  direction  of  the  currents  and  winds,  and  also  a  trans- 
position of  the  climates  themselves — sometimes  toward  the  north,  and 
sometimes  toward  the  south  ;  the  most  distinct  contrariety  in  this  respect 
is  thus  produced,  in  some  cases,  between  the  western  side  of  one  conti- 
nent and  the  eastern  side  of  the  continent  opposite  to  it.  It  is  principal- 
ly between  the  Old  and  New  Worlds  that  this  contrast  is  most  striking ; 
at  equal  latitudes,  the  western  shores  of  Europe,  and  those  which  face 
them  on  the  other  side  of  the  Atlantic,  have  very  different  climates — a 
fact  which  is  caused  by  the  changes  produced  by  marine  currents,  the 
wind«,  and  all  the  other  atmospheric  phenomena. 


76  THE  EARTH. 


CHAPTER  XL 

HARMONY  OF  SHAPE  IN  OCEANS. — THE  TWO  BASINS  OF  THE  PACIFIC. — THE 
TWO  BASINS  OF  THE  ATLANTIC. — THE  ARCTIC  FROZEN  OCEAN  AND  THE  AN- 
TARCTIC CONTINENT. — CONTRASTS,  AN  ESSENTIAL  CONDITION  OF  PLANET- 
ARY VITALITY. 

The  harmony  of  the  continental  forms  is  fully  paralleled  by  that  of  the 
oceanic  configuration.  The  Southern  Ocean  alone — that  mighty  breadth 
of  waters,  in  comparison  with  which  all  the  other  oceans  seem  but  mere 
arms  of  the  sea — extends  over  nearly  an  entire  hemisphere  of  our  planet. 
Notwithstanding  its  enormous  dimensions,  it  none  the  less  exhibits  a  most 
hai-monious  ensemble,  caused  partly  by  the  amphitheatre  of  shore  spread 
all  round  the  Pacific,  from  Van  Diemen's  Land  to  Tierra  del  Fuego ; 
partly  also  by  the  marvelous  belt  of  the  Polynesian  archipelago.  T]iese 
numerous  and  lovely  islands,  which  Ritter  calls  the  "  Milky  Way  of  the 
ocean,"  are  dotted  obliquely  over  the  whole  breadth  of  the  south  seas, 
from  the  Philippines  to  Easter  Island,  dividing  the  immense  basm  of  the 
Pacific  into  two  sheets  of  water,  distinct  from  each  other  both  by  their 
winds,  the  course  of  their  currents,  and  the  undulations  of  their  waves. 
Thus  the  great  hemisphere  of  waters  constitutes  a  kind  of  oceanic  pair, 
in  accordance  with  the  same  law  which  distributed  the  land  in  three  con- 
tinental pairs. 

The  tortuous,  valley  of  the  Atlantic,  which  separates  the  Old  World 
from  the  New,  is  also  decisively  divided  into  two  basins,  difiering  in  the 
shape  of  their  outline,  their  climates,  winds  and  currents.  An  ideal  line, 
traced  from  the  Cape  Verd  Islands  to  the  nearest  of  the  Antilles,  marks 
the  limit  of  separation  between  the  two  halves  of  the  great  oceanic  valley. 
On  one  side,  the  South  Atlantic  spreads  out  in  a  vast  semicircle  between 
the  scarcely  undulated  shores  of  the  more  massively  formed  continents; 
on  the  other,  the  North  Atlantic  gradually  contracts  toward  the  polar 
regions,  throwing  out,  both  to  right  and  left,  gulfs,  channels,  and  inland 
seas.  On  the  east,  the  Mediterranean,  the  British  and  the  Irish  Channels, 
the  North  Sea,  and  the  Baltic ;  on  the  west,  the  Caribbean  Sea,  the  Gulf 
of  Mexico,  the  isle-dotted  estuary  of  the  St.  Lawrence,  Baffin's  Bay,  and 
Hudson's  Channel  and  Bay — all  these  appear  to  correspond  on  either 
side  of  the  ocean,  and,  by  the  resemblance  of  their  outlines,  add  to  the 
harmony  of  the  continents  themselves.  Thus  the  general  form  of  the 
two  Atlantic  basins  recalls  to  mind  the  two  continental  pairs,  the  shores 
of  which  they  bathe.  The  northern  basin,  bordered  as  it  is  by  variously 
articulated  lands,  is,  from  this  very  cause,  the  richest  of  the  two  oceans  in 


THE  rOLAE  REGIONS.  77 

indentations  of  every  kind,  and  is  also  that  which  was  destined  by  nature 
to  become  the  high-road  of  the  commerce  of  nations. 

The  Indian  Ocean,  shut  up,  as  it  is,  in  the  immense  hollow  formed  by 
the  coasts  of  Africa,  Arabia,  the  Gangetic  peninsula,  the  Sunda  Isles,  and 
Australia,  can  not  exhibit  the  same  characteristic  of  duality  as  the  two 
other  oceans — the  Southern  Ocean  and  the  Atlantic.  If,  however,  we 
take  into  account  the  ancient  geological  conditions  of  Asia,  we  may,  pei-- 
haps,  be  warranted  in  looking  upon  the  Caspian,  the  Sea  of  Aral,  and  the 
other  lakes  of  Western  Asia,  as  the  remains  of  the  former  ocean  which,  in 
the  northern  hemisphere,  formed  the  equipoise  to  the  Indian  seas.  There 
would  then  have  been  three  double  oceans,  just  as  there  are  three  conti- 
nental pairs.  Added  to  this,  it  is  probable  that  the  northern  and  southern 
polar  regions  likewise  afford  an  instance  of  an  equilibrium  existing  between 
land  and  water.  We  are  at  present  but  very  imperfectly  acquainted 
with  the  regions  either  of  the  north  or  south  poles ;  but  the  explorations 
of  navigators  and  the  investigations  of  meteorologists  more  and  more 
tend  to  confirm  the  old  hypothesis,  which  supposed  that  open  sea  extend- 
ed round  the  Arctic  pole,  and  that  the  circle  of  the  south  pole  was  occu- 
pied by  a  covering  of  dry  land.  If  this  be  really  the  case,  the  harmony 
of  the  continental  masses,  and  the  sheets  of  water  which  are  interspei'sed 
among  them  over  the  surface  of  the  planet,  is  admirably  completed  by 
the  contrast  between  the  two  poles  of  land  and  water  which  occupy  the 
two  extremities. 

The  general  similarities  and  the  great  contrasts  which  we  have  now 
pointed  out  constitute  but  a  small  number  of  the  features  of  this  kind 
which  the  surface  of  the  globe  presents,  and  it  would  be  an  easy  thing 
thus  to  follow  out  our  parallels  from  sea  to  sea,  frona  river  to  river,  and 
from  mountain  to  mountain.  But  the  purely  external  symmetry  pre- 
sented by  the  continental  configurations  is  a  trifling  matter  compared 
with  the  profound  harmony  resulting  from  the  alternation  of  winds,  cur- 
rents, climate,  and  all  the  geological  phenomena ;  it  is  not  in  the  various 
portions  of  the  globe  but  in  their  working  action  that  we  must  seek  for 
the  real  beauty  of  the  earth.  Planetary  vitality  is  composed  of  perpet- 
ual contrasts  in  a  perpetual  harmony,  and  these  very  contrasts  are  inces- 
santly being  modified.  Continents,  seas,  and  atmosphere — and,  in  a  more 
special  way,  every  mountain,  every  peninsula,  every  river,  every  marine 
current,  every  wind  that  blows — may  be  considered  as  the  organs  of  the 
globe  on  which  we  live;  it  is  therefore  by  watching  these  organs  at 
Avork,  and  by  studjiing  deeply  and  thoroughly  their  action  and  reaction, 
that  we  can  best  arrive  at  an  acquaintance  with  the  physiology  of  the 
planetary  body. 

Physical  geography  is  nothing  else  but  the  study  of  all  these  terres- 
trial harmonies.  An  inquiry  into  the  superior  harmonies  which  emanate 
from  the  relations  of  mankind  to  the  planet  which  is  the  scene  of  human 
life  must  be  left  to  history,  the  task  of  which  is  to  describe  them. 


THE  EARTH. 


CHAPTER  Xn. 

GENERAL   ASPECT    OF    PLAINS. — ALLUVIAL    PLAINS. CULTIVATED   PLAINS. — 

UNIFORMITY  IN  UNCULTIVATED  PLAINS. — ^VARIETIES  IN  APPEARANCE  PRO- 
DUCED BY  CLIMATES  AND  DIFFERENT  PHYSICAL  CONDITIONS. 

The  portions  of  the  terrestrial  surface  on  which  the  vitality  of  the 
globe  shows  itself  with  the  least  intensity  and  variety  are  those  countries 
which  present  the  slightest  diversities  of  level.  In  these  regions,  the  flat- 
ness or  slight  declivity  of  the  surface  of  the  earth  prevents  the  waters 
from  flowing  rapidly ;  the  country  exhibits  the  same  amount  of  vegeta- 
tion, or  the  same  sterility,  over  vast  extents,  and  its  general  aspect  is  often 
most  monotonous.  Nevertheless,  in  spite  of  the  uniformity  of  a  flat  dis- 
trict, the  phenomena  of  nature  are  all  the  more  easily  observed  there,  be- 
cause they  are  developed  in  a  more  simple  and  regular  manner. 

Nearly  half  of  the  continental  regions  is  composed  of  low  and  compara- 
tively level  lands,  the  even  or  gently  inclined  surface  of  which  still  testi- 
fies to  the  action  of  the  waters  of  the  ocean,  or  of  the  inland  seas  by 
which  it  was  formerly  covered.  These  are  former  sea-beds,  which  have 
emerged,  from  the  deep;  and,  from  the  uniformity  of  their  appearance — 
often  much  resembling  a  tract  of  ocean — contrast  sharply  with  the  high 
lands  or  mountains  surrounding  them.  Some  of  these  plains,  which  are 
watered  by  streams  and  rivers,  have  been  greatly  modified  by  the  courses 
which  the  latter  have  taken ;  and  by  means  of  the  fertile  alluvium  that 
has  been  brought  to  them,  and  the  moisture  which  penetrates  them,  have 
spontaneously  given  birth  to  immense  forests.  They  then  lose  their  re- 
semblance to  the  surface  of  the  sea,  except  when  looked  at  from  the  top 
of  some  lofty  bluff,  around  which  the  thick  trees  seem  to  crowd  like  bil- 
lows. At  length,  when  man  comes  to  take  possession  of  the  plains,  to 
erect  his  towns,  and  to  cultivate  the  soil,  he  introduces  a  great  variety 
into  these  uniform  tracts,  and  never  ceases  to  modify  their  primitive  as- 
pect. These  low-lying  regions,  which,  by  reason  of  the  flatness  of  the 
ground,  are  destined  to  be  the  scene  of  but  slight  activity  in  the  planet- 
ary life,  have  become  the  principal  seat  of  mankind,  and  it  is  there  that 
civilization  makes  its  most  remarkable  progress.         « 

The  plains  which  best  retain  their  appearance  of  times  gone  by  are 
those  which,  owing  either  to  the  want  of  rain,  or  the  almost  complete  ab- 
sence of  slope  either  in  one  direction  or  another,  are  watered  by  only  a 
small  number  of  streams,  or  sometimes,  throughout  vast  tracts  of  country, 
are  utterly  without  them.  For  this  reason,  in  many  parts  of  the  globe,  a 
plain  and  a  desert  are  almost  synonymous.  Setting  aside  the  low  lands 
which  have  been  brought  under  cultivation,  the  plateaux  and  the  inter- 


ASPECT  OF  PLAINS.  79 

vening  mountain  chains,  we  find  that  there  is  a  coincidence  between  most 
of  the  large  level  plains  and  the  continental  deserts.  Thus  the  western 
and  eastern  regions  of  the  Sahara,  the  Nefoud  of  Arabia,  the  steppes  of 
the  Caspian,  the  Aral,  the  Balkash,  and  the  tundras  of  Siberia,  are  at  the 
same  time  the  most  extensive  plains  and  the  most  widely-spreading  des- 
erts on  the  face  of  the  globe.  The  general  axis  of  the  principal  plains  in 
the  Old  World,  as  well  as  that  of  the  deserts,  mountains,  and  continents 
themselves,  is  set  in  a  direction  from  southwest  to  northeast;  while  in 
the  New  World  the  axis  of  the  low-lying  lands  tends  from  north  to 
south  in  a  parallel  line  to  the  chains  of  the  Rocky  Mountains  and  the 
Andes. 

All  lands  which  are  bare  plains,  destitute  of  large  trees,  resemble  one 
another,  on  account  of  their  uniformity.  On  the  surface  of  these  plains, 
as  on  the  sea,  it  is  only  necessary  to  scan  the  horizon  round  in  order  to 
perceive  clear  proofs  of  the  rotundity  of  the  globe.  Although  the  sight 
reaches  without  difficulty  over  the  bare  ground,  or  its  green  carpet  of 
plants,  yet  the  bases  of  hills  and  the  trunks  of  trees  which  appear  at  the 
limits  of  the  plain  are  hidden  by  the  convexity  of  the  earth.  At  first  we 
only  perceive  the  summits  of  the  hills  and  the  branches  of  the  trees;  then,  in 
proportion  as  we  draw  nearer,  the  lower  declivities  and  the  trunks  of  the 
trees  begin  to  make  their  appearance,  in  the  same  way  as,  in  the  open  sea, 
the  hull  of  a  ship  is  not  seen  until  long  after  the  sails  and  masts  have 
come  into  view.  Lastly,  as  on  the  ocean,  the  variable  aspect  of  the  sky, 
to  which,  in  hilly  countries,  we  are  in  the  habit  of  paying  only  a  second- 
ary attention,  here  regains  all  its  importance,  and  becomes  the  principal 
feature  in  the  landscape.  The  uniform  and  motionless  surface  of  the  plain 
slopes  down  toward  the  horizon,  like  the  back  otf  a  gigantic  shield,  and  its 
whole  extent  offers  no  object  which  can  arrest  the  attention ;  but  above, 
on  all  sides,  stretches  the  enormous  dome  of  the  atmosphere,  with  its  fit- 
ful play  of  light  and  shade,  the  successive  gradation  of  its  colors,  from 
deep  blue  to  fiery  purple — its  clouds,  which,  chasing  one  another  across 
the  sky,  first  disperse  and  then  cluster  together ;  drawing  themselves  out 
into  long  transparent  lines,  or  accumulating  in  massCT  of  a  sombre  gray. 
Occasionally,  when  the  air  which  hangs  over  the  plain  is  unequally  heat- 
ed by  the  rays  of  the  sun,  distant  objects  assume  a  distorted  shape,  seem- 
ing nearer  than  they  really  are,  or,  perhaps,  inverted,  producing  that  fan- 
tastic illusion  called  a  mirage,  which  was  formerly  believed  to  be  tin* 
work  of  mocking  genii.  , 

Although  all  the  bare  plains  on  the  various  continents  resemble  one  an- 
other in  the  curvature  of  the  ground,  the  circularity  of  the  horizon,  an<l 
the  play  of  the  atmosphere,  yet  their  aspect  sometimes  varies  much  in 
diftercnt  countries,  according  to  the  geological  nature  of  the  soil,  the  mean 
temperature,  the  changes  of  the  seasons,  the  direction  of  the  winds,  the 
quantity  of  rain-fall,  and  all  the  other  physical  conditions  of  the  region  ^ 
generally.  Thus,  a  clayey  plain  is  hard  and  compact,  like  the  ground  of 
a  threshing-floor  which  has  constantly  been  beaten  with  the  flail ;  another, 


80  .  2'^A'  EAETH. 

the  rocks  of  which  are  of  a  calcareous  nature,  is  intersected  here  and  there 
by  ravines  with  perpendicular  sides ;  another  is  sandy,  and,  under  the 
influence  of  the  wind,  is  rippled  with  waves  like  the  surface  of  the  sea. 
Some,  but  these  are  rare,  present  vast  extents  completely  destitute  of 
vegetation ;  others  offer,  here  and  there,  a  solitary  green  plant ;  but  every 
one  of  them  is  a  plant  of  the  same  species ;  and  one  may  travel  whole 
days  in  these  deserts  without  seeing  any  other  representatives  of  the 
vegetable  world.  The  greater  number  of  plains  have,  it  is  true,  a  Flora, 
composed  of  a  tolerably  large  number  of  species ;  but  two  or  three  plants, 
which  are  commoner  than  the  others,  appearing  uniformly  on  hundreds 
and  thousands  of  acres,  have  appropriated  to  themselves  the  whole  dis- 
trict, and  thus  give  it  a  special  character.  Lastly,  some  solitudes  are 
temporarily,  during  the  rainy  season,  or  even  during  the  whole  year,  mag- 
nificent and  verdant  prairies  enameled  with  flowers.  These  are  the  tracts 
which  man  can  most  easily  turn  to  account  by  breaking  them  up  with 
the  ploughshare. 


THE  FRENCH  LANDES.  81 


CHAPTER  Xin. 

THE  FRENXH  LANDES. — THE  BRAXDES  AND  THE  ALIOS. — THE  CAMPINE. — 
THE  HEATHS  OF  HOLLAND  AND  NORTHERN  GERMANY. — THE  PUSZTA  OF 
HUNGARY. — THE  GRASSY  STEPPES  OF  RUSSIA. — THE  SALT  STEPPES  OF 
THE  CASPIAN  AND  THE  ARAL. — THE  TUNDRAS. 

Thanks  to  the  rains  blown  up  by  the  sea-breezes,  the  comparatively 
small  deserts  of  Western  Europe  do  not  assume  the  formidable  character 
of  the  Sahara,  or  the  Nefoud  of  Arabia.  Those  best  known  are  the  landes 
of  Gascony. 

The  old  tracts  of  French  landes  embrace  not  only  the  department 
which  takes  its  name  from  them,  but  also  include  half  of  La  Gironde,  as 
well  as  the  extreme  comer  of  Lot-et-Garonne,  extending  over  nearly 
2,500,000  acres.  This  region,  which  was  once  covered  by  the  waters  of 
the  Atlantic,  is  a  plateau  averaging  160  to  190  feet  in  height,  and  sinking 
in  a  gentle  decline  on  the  northeast  toward  the  Gironde  and  the  Garonne, 
on  the  west  toward  the  lakes  on  the  sea-shore,  and  on  the  south  toward 
the  River  Adour.  The  uniformity  of  the  great  plateau  of  the  landes  is  so 
great  that,  for  a  distance  of  twenty-eight  miles  between  Lamothe  and 
Labouheyre,  the  railroad  from  Bordeaux  to  Bayonne  is  perfectly  rectilin- 
ear; one  might  call  it  a  "  visible  meridian." 

For  some  years  past,  the  labor  of  man  has  done  much  in  turning  to  ac- 
count this  vast  domain,  once  so  neglected ;  private  individuals  and  com- 
munities have,  with  equal  ardor,  sought  to  enrich  themselves  by  replacing 
the  heath  with  pines  and  other  trees,  and  there  can  be  no  doubt  that,  at 
an  early  future,  the  whole  extent  of  the  landes  will  be  covered  with  for- 
ests and  cultivated  grounds.  There  are  now  but  few  places  where  we 
can  still  see  what  the  whole  plateau  once  was,  stretching  from  the  edge  of 
the  vineyards  of  Bordeaux  to  the  country  at  the  foot  of  the  first  Pyrenean 
hills. 

In  these  uninhabited  tracts  the  landscape  is  certainly  deficient  in  vari- 
ety, but  it  always  possesses  a  certain  grandeur  and  a  singular  charm  for 
those  who  love  nature  in  all  her  freedom.  All  round,  within  the  limited 
circle  which  is  surrounded  by  the  level  line  of  the  horizon,  nothing  is  to  be 
seen  but  a  thick  underwood  of  bramles  and  various  other  kinds  of  heath, 
springing  up  to  the  height  of  a  yard  or  two  above  the  ground.  During 
their  flowering-time  these  plants  mingle  a  light  shade  of  pink  with  their 
delicate  green,  but  they  are  always  roughened  with  a  number  of  heath- 
branches,  stripped  of  leaves,  and  black  as  if  charred  in  a  fire.  In  other 
spots  tall  ferns  have  taken*  possession  of  the  ground  and  fill  the  air  with 
tiieir  penetraling  odor.     Farther  on  we  come  upon  large  patches  of  furze 

F 


82 


THE  EABTH. 


and  broom,  which  flower  together  in  the  spring  and  cover  the  plain  with 
an  immense  veil  of  gold.  Mosses,  grasses,  and  briers  grow  together  along 
the  edges  of  the  paths ;  water-lilies,  and  other  aquatic  plants,  repose  qui- 
etly on  the  surface  of  the  muddy  pools ;  bunches  of  rushes  and  sedge 


Fig.  IS.  The  "  Landes"  of  Gascony. 


spring  up  in  the  spongy  earth  around  the  water.  And  this  is  all.  Per- 
haps, on  the  extreme  horizon,  a  bluish  line,  pointing  out  the  edge  of  a 
pine  forest,  may  be  faintly  visible. 

Over  a  vast  extent  of  the  landes  the  supei*ficial  soil  is  composed  of  a 
white  and  almost  unmixed  sand ;  but  in  general  it  is  very  much  mingled 


THE  LANDES  OF  OASCONT.  33 

with  vegetable  remains,  which  give  it  a  gray  or  blackish  color,  like  char- 
coal ashes.  Below  this  upper  layer  extends  a  stratum  of  agglutinated 
sand,  generally  of  a  rusty  color,  and  bearing  a  great  similarity  in  appear- 
ance to  ferruginous  sandstone;  the  hardened  dust  known  in  the  landes 
of  Medoc  under  the  denomination  of  "alios^^  owes  its  color  and  its  firm- 
ness to  the  continual  infiltration  of  rain-water,  which  can-ies  down  into 
the  ground  various  organic  substances  in  a  state  of  solution,  and  blends 
them  intimately  with  the  arenaceous  particles.  In  a  general  way  alios, 
notwithstanding  its  ferruginous  appearance,  contains  the  oxide  of  iron 
only  in  an  almost  imperceptible  proportion.  When  it  is  thrown  into  the 
fire  it  is  noticed  to  carbonize  slowly,  and  is  then  reduced  to  ashes ;  yet,  in 
certain  localities,  especially  in  raarehy  districts  where  the  argillaceous 
iron  is  naturally  formed,  the  subjacent  layer  is  gradually  changed  into  an 
actual  mineral.  Generally,  the  bed  of  alios,  which  is  hardest  where  it  is 
least  thick,  is  completely  impervious  to  water,  like  a  stratum  of  rock. 
Rain-water,  being  thus  checked  by  the  continuous  layer  of  cUios,  must 
necessarily  remain  in  the  upper  soil,  and,  during  the  wet  season,  the  sur- 
face of  the  landes  would  be  changed  into  one  great  marsh  if  care  were 
not  taken  to  cut  trenches  or  drains,  which  receive  the  overflow  of  the 
scattered  pools,  and  carry  it  either  to  the  different  rivulets,  or  to  the  lakes 
on  the  sea-shore.  In  order  to  cross  more  easily  the  sheets  of  water  which 
sometimes  extend  farther  than  the  eye  can  reach  between  the  patches 
of  heath,  the  shepherds  of  the  layides  have  adopted  the  custom  of  walk- 
ing and  watching  over  their  flocks  on  stilts  more  than  a  yard  high.  In 
this  respect  the  Lanusquets,  or  Landescots,  are  without  parallel  all  over 
the  world,  and,  if  I  am  not  mistaken,  in  the  history  of  mankind. 

Nearly  all  the  regions  of  Western  Europe,  which  were  in  early  ages 
covered  by  the  sea,  and  have  since  retained  the  uniformity  of  surface  of 
the  former  sea-beds,  have  long  since  come  under  cultivation  ;  such  as,  for 
instance,  the  low  ground  of  the  ancient  Gulf  of  Poitou,  the  filled-up  estua- 
ry of  Flanders,  the  largest  part  of  Holland,  and  German  and  Danish  Fries- 
land.  But,  farther  inland,  there  are  here  and  there  tracts  of  landes  like 
those  of  Bordeaux.  In  France  one  may  mention  those  of  Sologne  and 
Brenne,  which  were  fonnerly  a  vast  forest  of  about  1,234,000  acres  in  ex- 
tent, and  are  now  being  transformed  anew  by  patches  of  pines,  drainage, 
canals,  and  other  improvements.  In  Belgium  the  sandy  landes  of  the 
Campine,  which,  since  the  establishment  of  the  Germans  and  Batavi  in 
the  neighboring  countries,  have  always  been  a  flat  surface  of  heaths  dot- 
ted over  with  pools,  extended  in  1849  over  a  surface  of  345,000  ncres;  but 
the  brave  Belgian  husbandmen  who  laid  siege  to  these  landes  continue  to 
reduce  their  dimensions  at  the  rate  of  3950  acres  a  year.* 

In  Holland  and  the  north  of  Germany  the  belt  of  heaths  assumes  its 

greatest  width,  and  extends  over  a  much  more  considerable  surface  than 

that  of  the  landes  of  Gascony.    In  Holland  alone  an  extent  of  about 

4,196,875   acres,  more  than  half  the  territory,  consists  of  a  sandy  soil, 

•  Emile  de  Laveleve,  Revue  da  Deux  Mondes,  June,  1861. 


84 


THE  EARTH. 


which  was  once  nothing  but  a  vast  solitude,  the  uncultivated  parts  of 
which  still  contrast  most  strikingly  with  the  rich  polders  of  the  coast.  A 
great  part  of  this  sandy  regioli,  which  is  elevated,  upon  an  average,  48  feet 
above  the  sea,  is  covered  wnth  spongy  peat-mosses,  which  will  readily 
burn  after  having  previously  been  dried  by  means  of  drainage-canals,  and 
cut  into  pieces  of  a  jjroper  size.  One  fine  day  in  the  summer  time  the 
peasants  set  light  to  these  masses  of  dry  turf,  and  soon  the  conflagration 
spreads  over  wide  extents,  and  thousands  of  acres  are  burning  at  the 
same  time.  When  the  north  wand  passes  over  these  immense  fires  it  car- 
ries with  it  smoking  particles  of  the  smouldering  turf  hundreds  of  leagues 
away  from  Holland,  and  sometimes  even  to  the  centre  of  France,  Switzer- 


f    "^^jr'rr^fh 


X^^ 


(/ 


/AaiLsmli; 


Fig.  19.  Extent  of  the  Heath-smoke  in  1S57. 

land,  Bavaria,  and  Austria.  This  is  the  origin  of  those  dry  fogs,  or  north- 
em  fogs,  which  give  a  yellowish  tint  to  the  atmosphere,  and  sometimes 
half  hide  the  face  of  the  sun.*  However,  when  the  wind  is  favorable,  a 
comparatively  slack  fire  transmits  its  smoke  to  very  great  distances; 
thus,  in  1865,  at  the  time  of  the  fire  in  a  part  of  the  city  of  Limoges,  the 
cloud  of  smoke,  which  stretched  away  in  long  eddies  toward  the  west, 
was  perfectly  visible  as  far  as  Marennes,  a  distance  of  about  125  miles  in 
a  straight  line. 

*  EmJle  de  Lavelej'e,  Revue  des  Deux  Mondes,  Jnn.,  18G4.  M.  de  Lavelej-e  thinks  that 
the  name  of  "  brandes"  given  in  Gascony  to  the  high-growing  s])ecies  of  heath,  is  derived 
from  the  habit  they  have  of  burning  them.     In  German,  brand  signifies  burning. 


PLJjyS  OF  UUNOARY  AND  RUSSIA.  35 

The  landes  of  the  north  of  Europe  enjoy  a  colder  climate  than  those 
of  Gascony,  therefore  their  vegetation  is  less  developed  and  not  so  diver- 
sified ;  but  it  seems  that  in  both  belts  of  heath  the  composition  of  the  soil 
is  nearly  the  same.  In  Germany  and  in  Jutland,  as  well  as  in  France,  the 
yellow  color  of  the  sand  is  due  to  the  gradual  infiltration  of  the  juices  of 
the  plants,  which  are  loaded  with  tannin  ;  and  the  ferruginous-looking 
ti(fa^  which  is  found  at  a  certain  depth  in  the  substratum,  through  which 
the  roots  of  trees  can  not  penetrate,  is  no  doubt  nothing  else  than  a  bed 
of  hardened  sand  of  the  same  nature  as  the  alios  of  the  French  landes. 
In  Jutland,  where  this  bed  is  on  an  average  from  two  to  four  inches  in 
depth,  they  give  it  the  name  of  jern-al,  or  iron-sand.  In  England,  Scot- 
land, and  Ireland  a  thin  bed  of  "  iron-pan,"  of  the  same  appearance,  is 
found  under  the  large  bai'ren  heath-covered  moors. 

Very  different,  indeed,  in  their  vegetation  are  the  large  grassy  plains  of 
Hungary  and  Central  Russia ;  they  are,  in  fact,  immense  prairies,  not 
less  uniform  than  the  landes,  but  presenting  a  much  more  lovely  and 
pleasing  aspect,  especially  in  the  season  of  flowers.  The  Magyar  Piiszta., 
«o  celebrated  by  Petoefi,  was  formerly  a  lake  of  more  than  310  miles  in 
circumference,  bounded  on  one  side  by  the  large  bend  of  the  Danube, 
from  Pesth  to  Belgrade,  and  on  the  other  by  the  semicircle  of  the  Carpa- 
thians and  the  western  mountains  of  Transylvania.  The  soil,  which  is 
nourished  by  the  fertile  alluvium  that  the  Tisza,  the  Maros,  and  other 
rivers  bring  down  from  the  surrounding  mountains,  is  very  fertile,  and  in 
the  cultivated  districts  yields  abundant  crops.  Vast  extents,  which  arc 
left  as  natural  meadows,  look  like  perfect  seas  of  waving  grasses,  over 
which  roam  in  unrestrained  freedom  herds  of  half-wild  oxen  and  those 
uncouth  horses  which  are  ridden  by  the  rude  Czikos  troopers.  The 
beauty  of  these  green  and  flowering  plains,  dotted  over  with  low,  mud-# 
built  houses,  often  hidden  almost  to  the  roofs  in  the  tall  herbage,  is 
heightened  by  the  contrast  afforded  by  the  wide  semicircle  of  blue 
mountains  forming  the  distant  horizon. 

The  grassy  steppes  of  Central  Russia  do  not  possess,  like  the  Hunga- 
rian puszta,  this  beautiful  framework  of  lofty  mountains,  but  they  offer  a 
charm  no  less  peculiar  in  the  beauty  of  their  flowers  and  the  gracefulness 
of  the  ears  of  corn  gently  waving  in  the  breeze.  The  vast  region  of  the 
Tchomosjom  (black  earth),  thus  named  on  account  of  the  color  of  its  soil, 
is  still  in  great  part  a  sea  of  grasses,  varied  only  here  and  there  by  vil- 
lages, cultivated  fields,  and  rivers  flowing  slowly  between  steep  banks. 
The  Tchomosjom,  which  extends  over  the  valleys  of  the  Don,  the  Dnie- 
per, and  the  Volga,  comprehends  an  area  of  more  than  197,500,000  acres, 
nearly  twice  the  size  of  France,  and  throughout  this  immense  district  the 
vegetable  soil  is  of  a  depth  varying  from  three  to  fifteen,  and  sometimes 
even  reaching  to  thirty  and  sixty  feet.  Thus  the  geological  nature  of 
the  soil  proves  that  this  plain  is  not  of  oceanic  origin  ;  msLTine  debris  is 
not  found  in  any  part  of  it,  nor  any  of  those  irregular  boulders  brought 
down  from  the  mountain  glaciers  of  Scandinavia.     The  "  black  lands" 


gg  THE  EARTH. 

were  formerly  an  irregularly  shaped  continent,  surrounded  on  all  sides 
by  water.  Though  they  are  incessantly  fertilized  by  the  remains  of  de- 
cayed turf,  yet  they  seem  unable  to  nourish  the  roots  of  trees ;  forests, 
therefore,  are  entirely  wanting  in  these  regions ;  thanks,  also,  to  the  nat- 
ural drainage,  there  are  no  stagnant  swamps.  These  lands,  prepared  for 
culture  by  a  grassy  vegetation  for  many  thousands  of  centuries,  are 
among  the  best  in  the  world  for  the  production  of  cereals,  and  sooner  or 
later  they  will  become  one  vast  field  of  corn.* 

To  the  south  of  the  Tchornosjom  there  are,  here  and  there,  some  oases 
of  the  same  nature  which  are  equally  remarkable  for  the  richness  of  their 


Fig.  20.  The  "  Black  Lands"  of  Russia. 


vegetation ;  but  the  greater  part  of  the  steppes  are  former  sea-beds, 
which  have  emerged  at  a  recent  epoch,  and  exhibit  no  traces  of  verdure 
except  in  the  spring.  The  heat  of  summer  soon  scorches  up  the  grass, 
and  the  flocks  which  graze  on  these  vast  plains  are  obliged  to  take  ref- 
uge by  the  banks  of  the  rivers  in  order  to  obtain  their  food.  The  only 
oases  of  the  steppes  of  the  Don  and  the  Dnieper  are  those  districts  in 
*  Buprecht,  Bulletin  de  F Academic  de  Petershourg,  voL  vii.,  No.  5. 


THE  RUSSIAN  STEPPES.  87 

wliich  the  inhabitants  have  been  able  to  renew  and  purify  the  soil  by  the 
use  of  spring  water.  Some  villages,  which  were  founded  in  the  last  cen- 
tury by  German  colonists,  are  perfect  little  nests  of  verdure,  the  beauty 
of  which  contrasts  most  strikingly  with  the  formidable  aspect  of  the  sur- 
rounding solitudes. 

Nearly  all  the  countries  of  Russia  and  Tartary,  which  are  situated  be- 
low the  level  of  the  sea  in  the  great  Caspian  depression,  are  steppes  of  a 
still  more  arid  and  desolate  character  than  those  even  of  southern  Russia. 
They  are  interminable  tracts  of  loose  sand,  interspersed  with  banks  of 
hard  clay,  like  a  threshing-floor  beaten  solid  by  the  flail,  and  beds  of  rock 
here  and  there  intersected  by  clefts  in  which  a  little  vegetable  soil  some- 
times accumulates.  These  steppes  of  sand  or  clay  comprehend  the  prin- 
cipal part  of  the  western  basin  of  the  Caspian ;  the  rocky  steppes  extend 
to  the  east  toward  Tartary ;  lastly,  the  salt  plains,  which,  by  their  efllores- 
cence,  bear  witness  to  the  fact  of  the  former  extension  of  the  sea,  occupy 
a  considerable  tract  between  the  course  of  the  Volga  and  that  of  the 
Yak.  There,  too,  is  situated  the  desert  of  Narin,  the  clayey  and  barren 
surface  of  which  is  scattered  over  with  sandy  plateaux  covered  with  ver- 
dure, and  crossed  from  north  to  south  by  a  chain  of  downs  sheltering  the 
pastures  which  lie  half  hidden  in  the  hollows.*  With  the  exception  of 
these  scanty  green  patches,  which  are  frequented  by  some  few  wandering 
tribes,  nearly  the  whole  of  the  Caspian  depression  is  the  very  picture  of 
aridity.  No  natural  meadows  reach  the  eye,  like  those  in  t#B  steppes  of 
the  Dnieper,  the  Don,  and  the  Irtysh ;  and  the  pastures  occupy  only  a 
very  limited  breadth  at  some  considerable  distance  to  the  north  of  the 
present  sea-shore.  When  the  locusts  settle  down  there,  which  is  fre- 
quently the  case,  not  a  blade  of  grass  is  left,  and  the  very  reeds  in  the 
marshes  are  eaten  down  to  the  level  of  the  water. 

It  is  well  known  what  an  inauspicious  aspect  the  surface  of  the  steppes 
present  in  the  middle  of  winter,  when  all  is  hidden  under  the  snow,  and 
the  freezing  wind  stirs  up  this  silvery  sea  iqto  waves  and  eddies.  But 
even  in  the  most  joyous  season  of  the  year  the  immense  extent  of- white 
sand  and  reddish  clay,  varied  here  and  there  with  scanty  shrubs  of  worm- 
wood and  euphorbia,  with  their,  sombre-colored  leaves,  likewise  presents 
a  most,  forbidding  aspect.  The  vast  tracts  of  ground,  which  are  crossed 
by  travelers  in  cars  drawn  by  horses  at  full  gallop,  appears  like  a  fiery- 
colored  sheet  striped  with  long  gray  lines.  Here  and  there  ravines,  hol- 
lowed in  the  soil  by  the  toiTents  of  rain-storms,  have  to  be  crossed  with 
great  labor;  then  some  marsh,  with  its  thick  whitish  waters  seen  in 
glimpses  through  a  forest  of  reeds,  has  to  be  avoided.  In  the  distance  a 
border  of  blood-red  saltwort  betrays  the  presence  of  a  salt  pool,  and  quite 
in  the  extreme  horizon,  heavy  hanging  clouds,  in  long  rows,  one  above 
the  other,  point  out  the  vicinity  of  the  sea-shore.  The  soil  reflects  an  in- 
tolerable amount  of  heat.  At  the  same  time  the  breeze,  drawn  as  by  a 
centre  of  attraction  to  the  burning  surface  of  the  steppes,  raises  before  it 

*  Pallas. 


88  THE  EARTH. 

columns  of  dust ;  at  the  side  of  the  car  the  debris  of  witliered  plants  may 
be  seen  strangely  bounding  along  by  thousands  and  by  millions ;  these 
racers  of  the  steppes^  which  are  rolled  into  balls  by  the  wind,  seem  to  be 
having  a  contest  of  speed,  and,  keeping  close  to  the  earth,  pursue  each 
other  furiously,  sometimes  making  leaps  of  several  yards ;  one  might  al- 
most fancy  that  they  were  human  beings  hui'ried  along  in  some  demo- 
niacal race.  At  the  end  of  each  stage  the  traveler  stops  an  instant  before 
a  miserable  cabin,  half  buried  in  the  sand.  He  catches  a  glimpse  of  a  hu- 
man face  with  haggard  eyes  and  disordered  hair,  and  then  off  he  goes 
again  like  a  dart,  to  plunge  anew  into  the  desert.  It  is  seldom  that  he 
can  distinguish  in  the  distance  the  kibitka^  of  the  Calmucks  or  the  Kir- 
ghizes, or  the  tombs  formerly  raised  over  the  bones  of  warriors.  Fre- 
quently hundreds  of  miles  are  accomplished  without  seeing  any  other 
trace  of  man  having  passed  over  the  same  route,  except  the  ruts  left  by 
the  wheels  in  the  hardened  clay.*  In  these  solitudes  trees  are  almost 
completely  unknown,  and  the  few  that  are  found  there  are  looked  upon 
with  a  kind  of  adoration,  as  if  they  were  the  miraculous  gifts  of  some  divin- 
ity. Between  the  Sea  of  Aral  and  the  confluence  of  the  Tchoni  and  the 
Yatchi,  that  is  to  say  a  distance  of  310  miles  in  a  straight  line,  only  one 
tree  is  to  be  found,  and  this  is  a  species  of  poplar,  with  drooping  boughs, 
the  roots  of  which  creep  far  into  the  arid  soil.  The  Kirghizes  have  such 
a  veneration  for  this  solitary  tree  that  they  often  go  several  miles  out  of 
their  way  iiArder  to-  pay  it  a  visit,  and  each  time  they  hang  an  article  of 
their  clothing  upon  its  branches.  From  this  custom  the  name  of  sindt- 
richagatch,  or  "  rag-tree,"  has  been  given  to  the  desert  poplar.f 

The  plains  of  southern  Siberia,  which  extend  eastward  as  far  as  the  Al- 
tai Mountains  and  the  lake  of  Dsai-Sang,  present  a  very  diversified  aspect 
compared  with  the  steppes  of  the  Caspian,  and  even  with  the  landes  of 
France  and  the  heaths  of  Germany.  These  plains  are  intersected  in  vari- 
ous directions  by  chains  of  rounded  hills,  and  by  woods  of  coniferous 
trees,  which  here  and  there  \)Ound  the  horizon  and  give  a  little  life  to  the 
whole*  landscape.  Besides  the  meadow  grasses,  hundreds  of  plants  and 
shrubs  also  embellish  the  surface  of  the  ground.  In  the  spring  rosaceous 
plants,  thorny  plum-trees,  cytisi,  tulips,  and  other  plants,  with  white,  pink, 
yellow,  and  variegated  flowers,  glitter  on  the  greensward  of  the  undula- 
ting valleys  of  the  steppe.J 

In  the  north  of  Russia  and  Siberia  the  long  plains  which  descend  in  an 
imperceptible  slope  toward  the  Arctic  Ocean  are  not  less  solitary  than 
the  Caspian  steppes,  and  have  an  equally  formidable  aspect.  During  a 
great  part  of  the  year  the  circular  space  bounded  by  the  horizon  presents 
nothing  but  an  immense  winding-sheet  of  snow  rippled  by  the  wind. 
When  this  bed  of  snow  melts  under  the  summer  sun,  the  lowest  districts 
in  the  plain,  or  tundrcf,  appear  dotted  over  liere  and  there  with  plots  of 

*  Von  Baer,  Kaspische  Stiulien. — Pallas.  • 

+  Zaleski,  La  Vie  des  Steppes  Kirghizes. 

J  Humboldt,  Asie  Centrale  and  Tableaux  de  la  Nature. 


PLALVS  OF  SIBERIA.  89 

Sphagnmn  and  various  other  green  plants,  which  grow  and  swell  almost 
like  sponges  by  means  of  the  half-hidden  pools  of  water.  Nearly  the 
whole  extent  of  the  soil  is  covered  with  reindeer  moss  and  other  whitish 
lichens ;  and  one  might  readily  fancy  that  the  interminable  carpet  of 
winter  snow  was  still  spread  before  one's  eyes.  In  these  regions,  how- 
ever, the  earth  is  always  frozen  to  a  great  depth,  in  spite  of  the  rudiment- 
ary  vegetables  which  grow  on  its  surface  and  the  lagoons  of  w.ati'r  which 
sparkle  during  several  months  in  the  marshy  depressions  of  the  soil.* 

♦  Wrangell. 


90  THE  EARTH. 


CHAPTER  XIV. 

SEMICIRCLE  OF  DESERTS  PARALLEL  TO  THE  SEMICIRCLE  OF  LANDES  AND 
STEPPES. — THE  SAHARA. SANDS,  ROCKS,  OASES. — ^THE  DESERTS  OF  ARA- 
BIA.— THE  NEFOUD. — DESERTS  OF  IRAN  AND  THE  INDUS. — THE  DESERT 
OF  COBI. 

At  a  great  distance  to  the  south  of  this  zone  of  Zawcfe?,  prairie^steppes, 
and  tundras^  which  extends  in  an  irregular  semicircle  from  Prance  to 
Siberia,  there  is  another  zone  of  plains,  deserts,  and  plateaux  which 
curves  round  in  a  parallel  direction  to  the  former,  and  exhibits  a  still 
more  formidable  and  monotonous  aspect.  This  zone,  which  is  crossed  by 
an  imaginary  line  called  by  John  Reynaud  the  "equator  of  contrac- 
tion,"* comprehends  the  great  Sahara  of  Africa  and  the  deserts  of  Ara- 
bia, Persia,  Cobi,  and  Chinese  Mongolia.  This  zone  is  in  a  great  measure 
destitute  of  water  and  vegetation,  and,  on  the  whole,  is  much  less  accessi- 
ble to  man  than  the  northern  solitudes.  Not  only  is  it  more  intensely 
heated  by  the  solar  rays,  but  it  also  enjoys  a  much  less  amount  of  moist- 
ure on  account  of  the  chains  of  mountains  which,  at  several  points,  im- 
pede the  passage  of  the  rain-clouds,  and  especially  on  account  of  the  po- 
sition it  occupies  as  extending  diagonally  across  the  most  massive  por- 
tion of  the  two  largest  continents,  Africa  and  Asia. 

The  most  important  group  of  deserts  in  the  world  is  that  of  the  Sahara, 
which  extends  across  the  African  continent  from  the  shores  of  the  Atlan- 
tic to  the  valley  of  the  Nile.  This  immense  area  is  more  than  3100  miles 
from  east  to  west,  and  is,  on  an  average,  more  than  600  miles  in  breadth ; 
it  is,  in  fact,  equal  in  size  to  two  thirds  of  Europe.  This  is  the  part  of  the 
earth  in  which  the  heat  is  most  intense  ;  although  it  is  to  the  north  of  the 
equator,  yet,  as  regards  most  of  the  world,  it  is  the  real«80w^A,f  and  the 
principal  focus  of  attraction  for  the  atmospheric  currents.  In  this  region 
there  is  only  one  season,  viz.,  summer,  burning  and  merciless.  It  is  but 
rarely  that  rain  comes  to  refresh  these  regions,  on  which  the  solar  rays 
dart  vertically  down. 

The  mean  altitude  of  the  Sahara  is  estimated  at  2000  feet ;  but  the  lev- 
el of  the  soil  varies  singularly  in  the  different  districts.  To  the  south  of 
Algeria,  the  surface  of  the  Chott  Mel-R'ir,  the  remains  of  an  ancient  sea, 
which  communicated  with  the  Mediterranean,  is  at  the  present  time  more 
than  165  feet  below  the  Gulf  of  Cabes;  while  to  the  south  and  east,  the 
ground  rises  into  plateaux  and  mountains  of  sandstone  or  granite  to  a 
height  varying  from  3300  to  6600  feet.  In  the  centre  of  the  Sahara 
stands  the  Djebel-Hoggar,  the  sides  of  which  are  covered  with  snow  dur- 
*  Vide  above,  p.  56,  Fig.  13.  t  Carl  Ritter. 


DESERT  OF  THE  SAHARA.  91 

ing  three  months  in  the  year ;  from  December  to  March*  its  picturesque 
defiles  are  traversed  by  streams  which  flow  some  distance  and  lose  them- 
selves beneath  the  surrounding  plains.  This  group  of  lofty  mountains 
is  the  great  landmark  which  forms  the  boundary  between  the  eastern 
deserts,  or  the  Sahara  proper,  and  the  group  of  western  deserts,  desig- 
nated under  the  general  name  of  Sahel.  Farther  to  the  east,  the  oases 
of  Asben,  R'at,  and  Fezzan,  which  extend  obliquely  toward  the  shores  of 
the  Gulf  of  Sidra,  might  likewise  be  considered  as  the  frontier  between 
the  two  regions. 

The  Sahel  is  very  sandy.  Throughout  the  greater  part  of  its  extent, 
the  soil  is  composed  of  gravel  and  large-grained  sand,  which  does  not 
give  way  even  under  the  foot  of  the  camel.  Some  of  the  ranges  of  sand- 
hills which  rise  in  this  desert  are  chains  of  small  hills,  composed  of  heavy 
sand  which  resists  the  influence  of  the  wind.f  But  in  many  districts  of 
the  Sahel,  the  arenaceous  particles  of  the  soil  are  fine  and  small.  The 
trade-winds  which  pass  over  the  desert  distribute  these  sandy  masses 
into  long  waves  similar  to  those  of  the  ocean,  and  here  and  there  raise 
them  into  movable  sand-hills,  which  overwhelm  all  the  oases  which  lie 
across  their  path.  Traveling  toward  the  southwest,  in  which  direction 
they  are  driven  by  the  wind,|  the  sands  reach  the  northern  shores  of  the  , 
Niger  and  Senegal  at  many  points  of  their  course,  and  by  their  incessant 
deposits  gradually  drive  the  waters  of  these  rivers  toward  the  south.  To 
the  west,  the  sand  of  the  desert  encroaches  also  upon  the  ocean.  Off  the 
coast  which  stretches  between  Cape'Bojador  and  Cape  Blanco — pointed 
out  from  afar  by  the  highest  dunes  in  the  world — a  line  of  sand-banks  ex- 
tends far  out  into  the  sea.  These  banks  are  constantly  renewed  by  the. 
desert-wind  ;  and  the  Arabs,  who  go  to  collect  the  waifs  and  strays  from 
shipwrecked  vessels,  can  safely  venture  out  several  miles  from  the  shore.§ 
A  current  of  sand  is,  therefore,  constantly  passing  across  the  desert  from 
northeast  to  southwest.  The  debris  of  rocks  in  a  state  of  decomposition, 
and  the  particles  brought  to  the  coast  of  the  Gulf  of  Cabes  by  the  tide, 
which  is  veiy  powerful  at  this  point,  are  driven  before  the  wind  into  the 
plains  of  the  Sahel,  and  thence,  after  a  journey  lasting  hundreds  and  per- 
haps thousands  of  years,  they  at  last  reach  the  sea-shore  of  the  Atlantic, 
in  order  to  recommence  in  the  oceanic  currents  another  eventful  odyssey. 

Some  paits  of  the  eastern  Sahara  are  equally  sandy ;  but  the  principal 
parts  of  the  surface  of  this  desert  are  occupied  by  plateaux  of  rock  or 
clay,  and  by  groups  of  grayish  or  yellowish  mountains.  The  chains  of 
sand-hills  are  numerous,  and,  like  those  of  the  west,  they  travel  incessant- 
ly under  the  impulse  of  the  wind  in  a  south  or  southwest  direction.  ||  The 
rocky  plateaux  are  crossed  and  recrossed  here  and  there  by  wide  and 
deep  clefts,  which  are  gradually  filled  by  the  drifted  sand,  and  into  which 

*  Duveyrier,  Exploration  du  Sahara,  vol.  i.,  p.  120. 

+  Vide  in  vol.  ii.  the  chapter  on  "Dunes."  ♦ 

t  Duveyrier,  Exploration  du  Sahara,  vol  i. ,  p.  9.  §  Carl  Ritter,  Erdkunde, 

II  Greorges  Pouchet,  Dongolah  et  la  Nubie. 


92  THE  EARTH. 

the  traveler  runs  the  risk  of  sinking,  like  the  mountaineer  into  the  cre- 
vasses of  a  glacier.  In  the  hollows,  patches  of  salt  take  the  place  of  the 
lakes  which  in  more  rainy  countries  would  be  found  there. 

Those  districts  of  the  Sahara  which  are  destitute  of  oases  present  a 
truly  formidable  aspect,  and  are  fearful  places  to  travel  over.  The  path 
which  the  feet  of  the  camels  have  marked  out  in  the  immense  solitude 
points  in  a  straight  line  toward  the  spot  which  the  caravan  wishes  to 
reach.  Sometimes  these  faint  foot-marks  are  again  covered  with  sand, 
and  the  travelers  are  obliged  to  consult  the  compass,  or  examine  the  hori- 
zon ;  a  distant  sand-hill,  a  bush,  a  heap  of  camels'  bones,  or  some  other 
indications  which  the  practiced  eye  of  the  Touareg  alone  can  understand, 
are  the  means  by  which  the  road  is  recognized.  Vegetation  is  rare,  de- 
prived as  it  is  of  the  moisture  which  it  requires ;  the  only  plants  to  be 
seen  are  the  Artemisia,  thistles,  and  thorny  Mimosas ;  in  some  sandy  dis- 
tricts there  is  a  complete  absence  of  all  kinds  of  vegetation.  The  only 
animals  to  be  found  in  the  desert  are  scorpions,  lizards,  vipers,  and  ants. 
During  the  first  few  days  of  the  journey  some  indefatigable  individuals 
of  the  fly-tribe  accompany  the  caravan,  but  they  are  soon  killed  by  tlie 
heat  ;*  even  the  flea  itself  will  not  venture  into  these  dreadful  regions.f 
The  intense  radiation  of  the  enormous  white  or  red  surface  of  the  desert 
dazzles  the  eyes ;  in  this  blinding  light,  every  object  appears  to  be 
clothed  with  a  sombre  and  preternatural  tint.  Occasionally  the  traveler, 
when  sitting  upon  his  camel,  is  seized  with  the  rdgle,  a  kind  of  brain-fe- 
ver, which  causes  him  to  see  the  most  fantastical  objects  in  his  delirious 
dreams.  Even  those  who  retain  the  entire  possession  of  their  faculties 
.and  clearness  of  their  vision,  are  beset  by  distant  mirages;  palm-trees, 
groups  of  tents,  shady  mountains,  and  sparkling  cascades,  seem  to  dance 
before  their  eyes  in  misty  vapor.  When  the  wind  blows  hard,  the  travel- 
er's body  is  beaten  by  grains  of  sand,  which  penetrate  even  through  his 
clothes  and  prick  like  needles.  Stagnant  pools,  or  Wells,  dug  with  great 
labor  in  some  hollow,  from  the  sides  of  Avhich  oozes  out  a  scanty  and 
brackish  moisture,  point  out,  each  day,  the  end  of  the  stage.  But  often, 
this  unwholesome  swamp,  where  they  hoped  to  be  able  to  recruit  their 
energies,  is  not  to  be  found,  and  the  people  of  the  caravan  must  content 
themselves  with  the  tainted  water  with  which  they  filled  their  flasks  at 
the  preceding  stage.  It  is  said  that  in  times  of  great  need  the  travelers 
have  been  compelled  to  kill  their  dromedaries  in  order  to  quench  their 
thirst  in  the  nauseous  liquid  which  is  contained  in  the  stomach  of  these 
animals. 

Terrible  stories  are  also  told  by  the  side  of  the  watch-fires,  of  caravans 
being  overtaken  when  amid  the  sand-hills  by  a  sudden  storm  of  wind,  and 
completely  buried  under  the  moving  masses ;  they  also  tell  of  whole  com- 
panies losing  their  way  in  the  deserts  of  sand  or  rocks,  and  dying  of  mad- 
ness after  having  undergone  all  the  direst  tortures  of  heat  and  thirst. 
Happily  such  adventures  are  rare,  even  if  the  accounts  of  them  are  at  all 

*  Daniel,  Handbuch  der  Geographie,  vol.  i.,  p.  446.       t  Duveyrier,  Exploration  du  Sahara. 


OASES  m  THE  DESERT.  93 

authentic.  Caravans,  when  led  by  an  experienced  guide  and  protected 
by  treaties  and  tribute  against  the  attacks  of  plundering  Arabs  and  Bei*- 
bers,  nearly  always  arrive  at  the  end  of  their  journey  without  having  un- 
dergone any  other  sufferings  than  those  caused  by  the  intolerable  heat, 
the  want  of  good  water,  and  the  coldness  of  the  nights ;  for  the  nights 
which  follow  the  burning  days  in  the  Sahara  are  in  general  very  cold.  In 
fact,  the  air  of  these  countries  being  entirely  destitute  of  aqueous  vapor, 
the  heat  collected  during  the  day  on  the  surface  of  the  desert  is,  owing  to 
the  nocturnal  radiation,  again  lost  in  space.  The  sensation  of  cold  pro- 
duced by  this  waste  of  heat  is  most  acute,  and  especially  so  to  th(?  chilly 
Arab.  Not  a  year  passes  without  ice  forming  on  the  ground,  and  white 
frosts  are  frequent.*  During  his  travels  in  the  country  of  the  Touaregs, 
M.  Duveyrier  observed  a  difference  of  more  than  129°  F.  between  the  low- 
est temperature  (24°  F.)  and  the  highest  (153°  F.) ;  but  it  is  probiable 
that  the  real  difference  between  the  extremes  of  heat  and  cold  amounts 
to  at  least  144  degrees. f 

In  all  those  countries  in  the  Sahara  where  the  water  gushes  out  in 
springs  or  descends  in  streams  from  some  group  of  mountains,  there  is  an 
oasisj  formed — a  little  green  island,  the  beauty  of  which  contrasts  most 
strikingly  with  the  barrenness  of  the  surrounding  sands.  These  oases, 
compared  by  Strabo  to  the  spots  "dotted  over  the  skin  of  the  panther,  are 
very  numerous,  and  perhaps  comprehend  altogether  an  area  equal  in  ex- 
tent to  one  third  of  the  whole  Sahara.  In  the  greater  part  of  this  region, 
the  oases,  far  from  being  scattered  about  irregularly,  are,  on  the  contrary, 
arranged  in  long  lines  in  the  middle  of  the  desert.  The  cause  of  this  is 
oither  the  higher  proportion  of  moisture  contained  in  the  aerial  currents 
which  pass  in  this  direction,  or,  and  perhaps  principally,  the  subterranean 
water  which  follows  this  slope,  and  here  and  tliere  rises  to  the  surface. 
Thanks  to  this  distribution  of  the  oases,  like  beads  on  a  necklace,  the  car- 
avans dare  to  venture  into  the  solitudes  of  the  Sahara,  their  stages  being 
all  marked  out  beforehand  by  the  patches  of  verdure  which  in  turn  rise  on 
the  horizon. 

The  oases  are,  par  excellence,  the  country  of  date-trees ;  in  the  neighbor- 
hood of  Mourzouk  there  are  no  less  than  thirty-seven  varieties.§  These 
trees  form  the  riches  of  the  tribe,  for  their  fruit  supplies  food  to  man  as 
Avell  as  to  beast — to  dromedaries,  horses,  and  dogs.  Below  the  wide  fan 
of  leaves,  which  quiver  in  the  blue  air,  are  thickly-growing  clumps  of 
apricot,  peach,  pomegranate,  and  orange-trees,  their  branches  loaded  with 
fruit,  and  vines  intertwining  round  the  trunks  ;  maize,  wheat,  and  barley 
ripen  under  the  shade  of  this  forest  of  fruit-trees,  and,  lower  still,  the 
modest  trefoil  fills  up  the  very  smallest  intervals  of  the  soil  which  iS  ca- 
pable of  irrigation.  In  order  not  to  encroach  on  this  precious  ground, 
which  is  the  very  life  of  the  whole  tribe,  the  inhabitants  construct  their 
hous^  on  the  most  unproductive  land  in  the  oasis,  and  even  on  the  very 

*  Carette.  t  Exjiloration  du  Sahara,  vol.  i.,  p.  110. 

t  Derived  from  the  ancient  Egyptian  word  ouahe,  signifying  "habitation."  §  Vogel. 


94 


THE  EAMTH. 


verge  of  the  desert.  Unfortunately,  these  wonderful  gardens  which  the 
traveler,  just  emerged  from  the  ocean  of  sand,  looks  upon  as  a  place  full 
of  enjoyment,  are  for  the  most  part  unhealthy,  on  account  of  the  constant 
evaporation  of  tepid  and  bad  water  which  the  irrigation-drains  bring  to 
the  foot  of  the  trees.  For  this  reason  the  Caesars  of  the  Lower  Empire 
used  to  send  convicts  to  the  oases,  in  order  that  they  might  get  rid  of 


Fig.  21.  Oueld-R'ir. 

them  the  sooner.*  But  the  supply  of  water,  which  is  so  precious  to  these 
gardens,  is  badly  regulated  ;  at  the  time  of  heavy  rains,  which  are,  how- 
ever, rare  in  the  desert,  the  brook,  suddenly  transformed  into  a  river, 
sometimes  destroys  the  channels  and  washes  away  the  trees ;  whereas,  if 
retained  in  vast  reservoirs,  this  water  might  be  the  means  of  extending 
the  limits  of  the  oasis.  New  tracts  of  cultivated  ground  may  even  be 
*  Humboldt,  Tableaux  de  la  Nature. 


ABABLUr  DESERTS.  95 

created* by  boring  artesian  wells;  this  has,  indeed,  been  done  in  some 
places,  though  in  a  rough  manner,  by  the  native  tribes.  In  eight  years, 
from  1856  to  1864,  the  French  engineers  dug,  in  the  Hodna  and  the  Sa- 
hara of  the  province  of  Constantineh,  eighty-three  wells,  which  yield  al- 
together 11,859  gallons  a  minute,  and  nourish  more  than  125,000  palm- 
trees  ;  a  few  strokes  of  the  boring-rod  have  thus  changed  the  terrible  as- 
pect of  the  desert  and  adorned  it  with  magnificent  groves.  No  doubt,  if 
all  the  subterranean  springs  of  the  Sahara  were  brought  to  the  surface, 
they  might  succeed  in  bringing  a  great  part  of  it  nnder  cultivation,  and, 
in  course  of  time,  in  modifying  the  climate  as  they  have  done  in  Egypt,* 
by  augmenting  the  quantity  of  rain  and  aqueous  vapors.  Added  to  this, 
the  examination  of  the  soil  and  the  remains  which  are  contained  in  it, 
proves  that  at  a  recent  geological  epoch  the  Sahara  was  much  less  sterile 
than  it  now  is.  The  tribes  of  the  Algerian  Sahara  say  that  at  the  time 
of  the  Romans  the  Ouad-Souf  was  a  great  river,  but  some  one  threw  a 
spell  upon  it  and  it  disappeared.! 

To  the  east  of  Egypt,  which  may  be  considered  as  a  long  oasis  situated 
on  the  banks  of  the  Nile,  the  desert  begins  again,  and  borders  the  whole 
extent  of  the  Red  Sea.  A  large  part  of  Arabia  presents  nothing  but 
sands  and  rocks,  and  toward  the  southeast,  in  the  Dahna,  there  are  soli- 
tudes which  no  traveler,  either  Arab  or  Frank,  seems  yet  to  have  crossed. 
To  the  north  and  east  stretch  the  Nefouds,  or  "  daughters  of  the  great 
desert,"  which  are  much  smaller  than  the  Dahna,  but  are  nevertheless  for- 
midable tracts  to  travel  over.  One  of  these  regions,  which  was  crossed 
by  Palgrave,  is  that  in  which  the  mass  of  sand,  formerly  deposited  there 
by  the  marine  currents,  affords  the  greatest  depth ;  in  certain  places  it  is 
330,  400,  and  even  500  feet  deep.  It  can  be  measured  by  the  eye  by  de- 
scending to  the  bottom  of  the  funnel-shaped  cavities,  which  the  springs 
of  water,  spouting  out  of  the  adjacent  granite  or  calcareous  rock,  have 
gradually  hollowed  out  in  the  bed  of  sand.  This  enormous  bed  of  mate- 
rial, which  represents  chains  of  pulverized  mountains,  does  not  exhibit  an 
even  surface,  as  one  would  expect,  but,  throughout  its  whole  expanse, 
presents  long  symmetrical  undulations,  similar  to  those  waves  which  roll 
in  the  Caribbean  Sea  under  the  even  influence  of  the  trade-winds.  These 
waves  stretch  from  north  to  south,  parallel  to  the  meridian ;  it  is  probable 
that  they  are  owing  to  the  movement  of  the  earth  round  its  axis.  The 
solid  rocks  beneath  unresistingly  obey  the  impelling  force  which  carries 
them  toward  the  east,  but  the  movable  sands  which  are  above  them  do 
not  allow  themselves  to  be  carried  away  with  an  equal  rapidity ;  each 
day  an  infinitesimal  quantity  remains  behind  and  seems  to  glide  toward 
the  west,  like  the  waves  of  the  ocean,  the  atmospheric  currents,  and  ev- 
ery thing  that  is  movable  on  the  face  of  the  globe.  J  The  parallel  furrows 
^f  sand  in  the  Nefoud  certainly  rise  to  a  greater  height  than  those  of 
the  other  deserts,  and  differ  much  in  their  aspect  from  the  smaller  waves 

*  Vide  the  chapter  on  "  Labor  of  Man."  *  Carette. 

X  FiWe  the  chapter  on  "Rivers." 


1)0  THE  EABTH. 

of  sand  formed  by  the  wind ;  but  the  reason  is,  that  the  bed  of  sand  in  this 
region  is  of  a  very  great  bulk,  and  because  at  this  point  the  swiftness  of  the 
globe  nearly  attains  its  niaximum,on  account  of  its  vicinity  to  the  equator.* 

To  the  east  of  the  Arabian  peninsula,  the  chain  of  deseits  is  prolonged 
obliquely  across  Asia.  The  principal  part  of  the  plateau  of  Iran,  occupy- 
ing a  quadrilateral  space,  surrounded  by  mountains  which  stop  the  rains 
in  their  passage,  consists  of  sterile  solitudes,  some  covered  with  saline- 
beds,  the  remains  of  dried-up  lakes,  others  spread  over  with  shifting  sands, 
which  the  wind  blows  up  into  eddies,  or  dotted  over  with  reddish-colored 
hills,  which  the  mirage  renders  either  nearer  or  more  distant  to  the  eye 
than  they  really  are,  incessantly  modifying  them  according  to  the  undu- 
lations of  the  atmosphere.  This  plateau  is  only  separated  from  the 
steppes  of  Turkestan  by  the  Elburz  Mountains,  and  is  continued  toward 
the  east  by  the  deserts  of  Afghanistan  and  Beloochistan,  which  are  not 
so  large,  and  much  easier  to  travel  over.  Even  the  rich  peninsula  of  In- 
dia is  protected  by  a  belt  of  sterile  tracts  situated  on  the  right  and  left 
of  the  Indus.  Between  each  of  the  five  rivers  (Punjaub),  which,  by  the 
union  of  their  waters,  form  the  great  river,  stretches  a  line  of  steppes  in 
which  the  torrent-waters  of  the  mountains  are  soon  lost.  The  soil  of 
these  steppes  is  nearly  every  where  barren,  except  on  the  edge  of  the  irri- 
gation canals  constructed  by  the  inhabitants  at  a  very  heavy  outlay. 

B'^yond  the  mighty  central  group,  whence  radiate  far  and  wide  the 
mountain-chains  of  Asia,  the  steppes  and  deserts,  mutually  alternating 
according  to  the  topogi-aphical  conditions,  and  the  abundance  or  scarcity 
of  water,  extend  over  a  space  of  more  than  1850  miles  between  Siberia 
and  China  Proper.  The  eastern  part  of  this  belt  is  called,  according  to 
the  languages,  Cobi  or  Chamo,  that  is  to  say,  the  desert  ^^ar  excellence, 
and,  from  its  enormous  dimensions,  corresponds  with  the  Sahara  of  Africa, 
situated  exactly  at  the  opposite  extremity  of  the  long  chain  of  solitudes 
which  stretches  right  across  the  Old  World.  The  mirage,  the  moving 
sand-hills  blown  up  into  eddies,  and  many  other  phenomena  described  by 
African  travelers,  are  found  in  certain  districts  of  the  Cobi,  just  the  same 
as  in  all  other  deserts.  But  the  cold  here  is  exceptionally  intense,  on  ac- 
count of  the  great  height  of  the  plateaux,  which  is  on  an  average  4950 
feet,  and  the  vicinity  of  the  plains  of  Siberia,  which  are  crossed  by  the 
polar  wind.  It  freezes  nearly  every  night,  and  often  during  the  day. 
The  dryness  of  the  atmosphere  is  extreme;  there  is  hardly  any  vegeta- 
tion, and  a  few  grassy  hollows  are  the  only  oases  of  these  regions.  From 
Kiahkta  to  Pekin,  there  are  only  five  trees  for  a  distance  of  400  to  500 
miles,  which  is  the  width  of  the  desert  in  this  part  of  Mongolia.f  The 
Cobi,  however,  like  the  Sahara,  was  formerly  covered  by  the  waters  of  the 
ocean ;  even  on  the  elevated  plateaux,  old  cliffs  may  be  noticed,  the  bases  of 
which  are  worn  away  by  the  waves,  and  long  strands  of  round  shingle  stretch 
around  the  area  which  was  formerly  occupied  by  a  now  vanished  gulf     ^ 

♦  Gifford  Palgrave,  Journal  of  the  Geographical  Society,  18G4. 
t  Kiis>ell-Killough,  Seize  milles  lieues,  p.  111. 


PLAINS  OF  THE  NEW  WORLD.  97 


CHAPTER  XV. 

I 

PLAINS   AND   DESERTS   OP    THE    NEW   WORLD. COMPARATIVE    HUMIDITY    OF 

THE    AMERICAN  CONTINENTS. — DISTRIBUTION   OP  SAVANNAS   AND   STERILE 
TRACTS. — THE  PRAIRIES  OP  NORTH  AMERICA. — THE  LLANOS  AND  PAMPAS. 

The  American  continent,  being  narrower  and  more  exposed  throughout 
its  whole  extent  to  the  moist  sea-breeze  than  the  larger  mass  of  the  Old 
World,  presents,  therefore,  but  a  very  small  number  of  districts  in  which 
the  dryness  and  sterility  are  to  be  compared  to  certain  parts  of  the  Sahara 
and  Arabia.  It  is  true  that  plains  occupy  a  relatively  much  larger  area 
in  the  New  World  than  in  the  continents  of  Asia  and  Africa ;  but  they 
are  for  the  most  part  regions  which,  from  the  abundance  of  water  and 
the  deposit  of  fluviatile  alluvium,  have  become  very  fertile.  Thus,  the 
low  grounds  which  extend  along  the  two  banks  of  the  Mississippi,  and 
especially  the  districts  lying  along  the  edges  of  the  Amazon  and  its  large 
tributaries,  are  covered  with  immense  forests,  which  are  perfect  seas  of 
trees  and  creepers,  into  which  no  one  would  dare  to  venture  without  a 
guide,  even  if  they  are  not  completely  impenetrable,  except  for  the  native, 
armed  with  his  machete.  The  selvas  of  the  Amazon  are  the  regions 
where  vegetation  exhibits  its  richest  exuberance,  and  over  the  most  ex- 
tensive area.* 

Plains  which  are  devoid  of  trees  occupy  very  considerable  tracts  of 
land  in  the  two  Americas,  and,  notwithstanding  the  absence  of  all  forest 
vegetation,  several  of  them  being  formed  of  fluviatile,  or  lacustrine  alluvi- 
um, are  extremely  fertile.  In  consequence  of  the  composition  of  the  soil, 
the  distribution  of  the  rain-fall  and  water-courses,  and  perhaps,  also,  in 
obedience  to  some  still  unknown  law  governing  the  apportionment  of 
plants  on  the  surface  of  the  earth,  savannas  of  the  various  grasses  alter- 
nate suddenly  with  virgin  forests.  This  unexpected  contrast  between 
the  wall  of  trunks,  through  which  the  sight  can  not  penetrate,  and  the 
unbounded  extent  of  the  grassy  plain  waving  in  the  breeze,  is  one  of  the 
most  striking  spectacles  imaginable.  In  the  basins  of  the  Mississippi,  the 
Amazon,  and  the  tributaries  of  the  La  Plata,  these  sudden  transitions  from 
forest  to  savanna  are  frequently  found  ;  next  to  the  great  rivers  and  large 
sheets  of  marshy  water,  they  are  the  most  prominent  feature  of  the  land- 
scape in  the  plains  of  the  New  World. 

Taken  as  a  whole,  the  grassy  expanses  of  America  are  all — like  the 
laiules,  the  steppes,  and  the  tundras  of  the  Old  World — regularly  ar- 
ranged in  a  line  parallel  to  the  axis  of  the  continents  themselves.  In 
North  America,  they  are  contained  in  the  vast  central  basin  formed  by 
•  Vide  the  chapter  oa  "  The  Earth  and  its  Flora." 

G 


98  THE  EARTH. 

the  Alleghanies  and  the  first  spurs  of  the  Rocky  Mountains.  In  South 
America,  they  likewise  occupy  a  part  of  the  depression  in  the  middle  of 
the  continent  between  the  plateaux  of  the  Guianas  and  Brazil,  and  the  first 
groups  of  the  Andes.  Thanks  to  the  rainy  sea-breezes  which  blow  over 
these  plains  either  from  the  north  or  south,  vegetation  is  here  kept  up,  at 
least,  during  several  months  of  the  year ;  and  nowhere,  even  in  the  less 
fertile  districts,  are  real  deserts  to  be  found.  These  plains,  which,  as  in 
Africa  and  Asia,  are  likewise  arranged  in  a  line  parallel  to  the  belt  of  sa- 
vannas and  to  the  continental  axis  of  America,  are  all  situated  on  the 
western  side,  on  the  slopes,  or  in  the  inner  basins  of  the  Rocky  Mount- 
ains and  the  Andes.  They  are,  however,  comparatively  inconsiderable, 
and  intersected  by  fluviatile  valleys,  some  of  which  terminate  in  lakes 
without  an  outlet,  while  others  run  down  to  the  sea. 

The  savannas  or  prairies  of  Illinois  and  the  other  Western  States  of  the 
American  Republic  resembled,  not  long  since,  the  Magyar  puszta  and  the 
grassy  steppes  of  Russia,  except  as  regarded  the  difference  of  vegetation 
attributable  to  climate.  Some  of  those  plains,  w^iich,  at  a  former  geolog- 
ical epoch,  were  covered  by  the  waters  of  Lake  Michigan,  have  not  yet 
been  transformed  into  cultivated  fields,  and  they  have  a  uniform  and  placid 
surface  like  that  of  a  lake.  The  flowering  grasses  gi'owing  on  them  wave 
and  quiver  in  the  wind  like  the  ripple  of  the  waves,  and  the  clumps  of 
trees  are  dotted  about  like  islands.  Here  and  there  these  islands  are 
grouped  into  archipelagos,  and  the  arms  of  the  prairies  which  surround 
them  fork  out  and  unite  again  like  the  arms  of  a  grassy  sea ;  one  single 
prairie,  situated  in  the  centre  of  the  State  of  Illinois,  is  so  vast,  that,  as  far 
as  the  eye  can  reach,  not  one  of  these  thick  clumps  of  trees  appears  in 
sight.  But  in  consequence  of  the  very  rapid  colonization  of  the  Western 
States,  these  countries  are  every  day  changing  their  aspect.  The  traveler, 
therefore,  must  not  delay  if  he  wishes  to  survey  these  immense  prairies, 
where  the  horizon,  as  on  the  sea,  is  only  limited  by  the  rotundity  of  the 
globe — where  the  grasses  are  so  high  that  they  reach  up  to,  and  bend 
over,  the  head  of  the  traveler,  and  the  roebuck  can  dart  through  them 
without  even  being  perceived !  Ere  long,  these  j^rairies  will  have  ceased 
to  exist,  save  in  the  narrations  of  Cooper,  the  novelist ;  the  furrows  of 
the  unrelenting  ploughshare  will  have  converted  them  all  into  cultivated 
fields.  The  Americans  are  active  in  turning  them  to  account  and  in  tak- 
ing possession  of  this  fertile  land.  The  country,  which  is  strictly  surveyed, 
is  divided  into  townships  of  about  six  miles  on  each  side,  and  subdivided 
into  square  miles,  which  are  again  separated  into  four  parts.  All  these 
quadrilateral  spaces  are  so  accurately  set  as  to  aspect  that  each  of  their 
sides  points  to  one  of  the  four  cardinal  points.  The  purchasers  of  small 
or  large  squares  never  allow  themselves  to  deviate  from  the  straight  line ; 
as  true  geometricians,  they  construct  their  roads,  build  their  cabins,  dig 
their  ponds,  and  sow  their  turnips  in  the  direction  of  the  meridian  or  the 
equator.  Thus  the  prairies,  once  so  beautiful  with  their  gently  undula- 
ting contour  and  their  misty  distances,  now  bear  a  strong  resemblance 


THE  PAMPAS.  99 

to  an  immense  chess-board.  Even  the  railway  engineers  will  hardly  make 
up  their  minds  to  cross  the  degrees  of  longitude  in  an  oblique  direction. 

In  the  southern  continent,  the  regions  which  correspond  with  the  prair- 
ies of  the  United  States  are  the  pampas  of  the  La  Plata  and  the  llanos 
of  Columbia.  These  latter  expanses,  so  well  described  by  Humboldt,* 
are  probably,  of  all  the  plains  in  the  world,  those  which  exhibit  in  their 
appearance  the  most  striking  contrast,  according  to  the  diflferent  seasons 
of  the  year.  After  the  rainy  season,  these  plains,  which  extend  over  the 
immense  zone  contained  between  the  course  of  the  Orinoco  and  the 
Andes  of  Caracas,  Merida,  and  Suma-paz,  are  covered  with  thick  grass, 
and  graminaceous  and  cyperaceous  plants,  among  which  the  sensitive 
and  other  species  of  mimosa  here  and  there  exhibit  their  delicate  foliage. 
Horses  and  oxen  wander  by  millions  over  these  magnificent  pastures. 
But  the  soil  gradually  dries  up,  the  water-courses  become  exhausted,  the 
lakes  change  into  pools  and  then  into  sloughs,  in  the  mud  of  which  croco- 
diles and  serpents  delight  to  wallow;  the  clayey  ground  shrinks  and 
cracks,  the  plants  wither,  and  are  torn  to  shreds  by  the  wind ;  the  cattle, 
driven  by  hunger  and  thirst,  take  refuge  in  the  neighborhood  of  the  great 
rivers,  and  multitudes  of  their  skeletons  lie  bleaching  on  the  plain.  This 
is  the  special  time  when  the  llanos  most  resemble  the  deserts  of  Africa, 
which  are  situated  farther  from  the  equator  on  the  other  side  of  the  At- 
lantic— all  at  once,  the  storms  of  the  rainy  season  inundate  the  soil,  mul- 
titudes of  plants  shoot  out  from  the  dust,  and  the  immense  yellow  ex- 
panse is  transformed  into  a  flowery  meadow.  The  rivers  overflow  their 
banks,  and  the  inundations  will  sometimes  extend  over  a  breadth  of  hun- 
dreds of  miles ;  the  ancient  islands,  called  "  tables"  or  rnesas^  form  the 
only  land  which  appears  above  the  troubled  sheet  of  waters. 

The  llanos  of  Venezuela  and  New  Granada  have  an  area  estimated  at 
154,000  square  miles,  nearly  equal  to  that  of  France.  The  Argentine 
pampas,  which  are  situated  at  the  other  extremity  of  the  continent,  have 
a  much  more  considerable  extent,  probably  exceeding  500,000  square 
miles.  This  great  central  plain,  which  forms  one  of  the  most  remarkable 
features  of  South  America,  stretches  its  immense  and  nearly  horizontal 
surface  over  a  length  of  at  least  1 900  miles,  from  the  burning  regions  of 
tropical  Brazil  to  the  cold  countries  of  Patagonia.  In  so  vast  a  territory, 
the  climate  and  vegetation  must  necessarily  differ  very  much,  and  yet  a 
great  monotony  prevails,  on  account  of  the  horizontal  character  of  the 
ground  and  the  want  of  water.  The  rivers  of  ihepatnpas^  the  Pilcomayo, 
the  Vermejo,  and  the  Salado,  which  rise  in  the  Andes  and  the  Sierra 
Aconquija,  ultimately  reach  the  great  fluviatile  artery  of  the  Parana,  but 
not  without  having  lost  a  large  part  of  their  waters  on  the  road,  owing 
to  the  evaporation  in  the  lagoons  and  marshes.  Farther  south,  the  Rio 
Dulce,  which  also  rises  in  the  ravines  of  Aconquija,  is  lost  in  a  salt  lake  at 
some  distance  to  the  west  of  the  Parana.  In  the  same  way  all  the  water- 
courses of  the  provinces  of  Catamarca,  Rioja,  San  Juan,  Mendoza,  and 
*  Tableaux  de  la  Nature  and  Voyage  dans  lea  Regions  Eqmnoxiales. 


100 


THE  EARTH. 


Fig.  22.  The  Pampas. 

Cordova,  growing  smaller  in  proportion  to  their  distance  from  the  mount- 
ains, ultimately  spread  out  into  marshes,  or  break  up  into  pools  ;  the  sand 
of  the  desert  gradually  absorbs  them.  The  Rio-Quinto,  which  formerly 
reached  the  sea,  and  emptied  itself  to  the  south  of  the  estuary  of  La  Plata 
into  the  bay  of  San-Borombon,  now  stops  at  about  the  middle  of  its  for- 
mer course ;  but  to  the  east  some  lagoons  connect  it  with  the  sources 
of  a  small  stream,  which  may  be  considered  as  the  Lower  Quinto.  The 
diminution  of  rains,  and  the  increase  of  evaporation  during  the  present 
geological  period,  have  resulted  in  severing  the  river  into  two  parts. 


THE  PAMPAS.  101 

The  western  plains,  wliich  partly  surround  the  Cordovan  group,  are 
dotted  over  with  prickly  j)lants,  brooms,  mimosas,  and  other  shrubs  of 
scanty  foliage.  There  is  only  a  short  turf  growing  upon  the  clayey  and 
compact  soil,  and  here  and  there  vast  salt  plains,  completely  devoid  of 
vegetation,  glitter  in  the  sun.  These  are  real  deserts,  which  were  former- 
ly crossed  by  travelers  in  caravans,  just  as  in  the  solitudes  of  Africa  and 
Persia.  The  carriages  which  now  run  regularly  between  the  towns  on 
each  side  of  the  plain  go  across  in  a  straight  line,  and  their  drivers  do 
not  even  take  the  trouble  to  trace  out  a  road.  Farther  to  the  east,  the 
pampa  proper  extends  from  north  to  south,  between  the  Salado  and  the 
regions  of  Patagonia.  Here  are  situated  the  immense  and  celebrated 
pasture-grounds  which  form  the  wealth  of  the  Argentine  Republic,  on  ac- 
count of  the  cattle  which  overrun  it  by  hundreds  of  thousands,  and,  in- 
deed, millions.  The  grassy  surface  seems  to  be  completely  flat ;  no  ob- 
ject interrupts  the  majestic  uniformity  of  the  landscape,  except,  perhaps, 
a  herd  of  oxen,  the  yellow  wall  of  some  estancia,  or  a  solitary  tree  spared 
by  the  hatchet  of  the  gaucJio.  Pools,  some  brackish  or  saline,  others  filled 
with  fresh  water,  are  scattered  over  the  prairie,  and  continue  the  wavy 
covering  of  grasses  with  their  tufts  of  rushes  and  reeds.  To  the  north  of 
the  Salado,  the  great  sea  of  grass  is  succeeded  by  thickets  of  mimosas, 
and  other  prickly  shrubs,  which  surround  the  small  savannas.  Lastly, 
beyond  the  windings  of  the  Pilcomayo,  bunches  of  palm-trees  are  seen 
here  and  there  among  the  clumps,  and  the  pampa^  called  in  this  district 
the  Great  Cfuico,  ultimately  joins  on  to  the  large  selvas  in  the  basin  of 
the  Amazon  by  swampy  grounds  and  isthmuses  of  forest 


102  TSE  EABTH. 


CHAPTER  XVI. 

AMERICAN  DESERTS. — THE  GREAT  BASIN  OP  UTAH. — THE  DESERTS  OF  COLO- 
RADO.—THE  ATACAMA  AND  THE  PAMPA  OF  TAMARUGAL. — DEPOSITS  OF 
SALT,  SALTPETRE,  AND   GUANO. 

In  North,  as  in  South  America,  the  deserts  proper  lie  to  the  west  of 
the  continent,  and  occupy  the  basins  commanded  by  the  parallel  or  di- 
vergent walls  of  the  Rocky  Mountains.  In  both  hemispheres  it  is  the 
want  of  rain  which  is  the  cause  of  the  sterility  of  these  expanses,  to  which 
the  moist  winds  can  not  obtain  access,  on  account  of  the  high  mountains 
by  which  the  plains  are  surrounded ;  but,  by  a  remarkable  contrast,  the 
rains  in  the  northern  continent,  which  are  stopped  en  route  before  reach- 
ing the  deserts,  are  those  brought  by  the  clouds  from  the  Pacific,  and  in 
the  southern  continent  those  which  come  from  the  Atlantic  with  the 
trade-winds.  In  the  north,  the  ridges  of  the  western  chains,  the  coast- 
range,  and  the  Sierra  Nevada  are  the  impediments  which  detain  the  moist- 
ure of  the  atmospheric  currents  of  the  neighboring  ocean :  in  the  south 
it  is,  on  the  contrary,  the  eastern  groups  of  the  Cordilleras  which,  by  op- 
posing the  course  of  the  Atlantic  trade-winds  from  the  northeast  and 
southeast,  are  the  cause  of  the  barrenness  which  exists  on  their  opposite 
declivities.*  Besides,  in  both  continents,  most  of  the  deserts,  whether 
plains  or  plateaux,  seem  to  have  been,  at  some  former  geological  epoch, 
leveled  by  the  waters  of  some  inland  sea. 

The  most  northerly  of  these  American  deserts  occupies,  to  the  west  of 
Lake  Utah,  a  jDart  of  the  space  called  the  "  Great  Basin,"  and  is  comprised 
between  the  principal  chain  of  the  Rocky  Mountains  and  the  Sierra  Ne- 
vada of  California.  The  desert  of  Utah  is  an  immense  surface  of  clay, 
dotted  over  with  thin  tufts  of  artemisia ;  in  certain  places,  however,  it  ex- 
hibits no  trace  of  vegetation,  and  resembles  a  causeway  of  concrete,  in- 
tersected by  innumerable  clefts,  forming  nearly  regular  polygons..  In  the 
midst  of  these  solitudes  no  rivulet  flows,  and  no  water-spring  gushes 
forth ;  only  after  journeying  for  many  a  long  hour  the  traveler  sometimes 
comes  upon  some  field  of  crystallized  salt,  a  white  expanse,  on  which  the 
clouds  and  blue  sky  are  reflected  as  on  the  surface  of  a  lake.  On  the  ex- 
treme horizon  some  volcanic  rocks  may  be  seen,  like  great  scoriae,  half 
veiled  by  warm  atmospheric  columns,  quivering  like  the  air  over  the 
flame  of  a  hot  brazier.  Across  these  vast  plains,  inhabited  only  by  a  pro- 
digious quantity  of  extraordinarily-shaped  lizards,  the  road  employed  by 
the  emigrants  used  to  pass,  which  was  so  soon  destined  to  be  supplanted 
by  the 'Pacific  Railway  from  New  York  to  San  Francisco.  Since  the  dis- 
*  Vide  the  chapters  on  "Winds"  and  "Rain." 


UTAH  AND  COLORADO.  103 

covery  of  California,  thousands  of  men  have  perished  in  this  desert,  and 
innumerable  horses  and  oxen  have  died  of  thirst ;  the  right  direction  of 
the  road  is  indeed  recognized  by  their  bones  lying  scattered  over  the 
ground.  The  traveler  is  obliged  to  stop  during  the  night,  for  fear  of 
losing  his  way,  when  he  no  longer  hears  the  sound  of  the  skeletons  crush- 
ing under  the  feet  of  his  steed.* 

Separated  from  this  desert  by  chains  of  mountains,  among  which  are  to 
be  found  several  shady  valleys  enlivened  by  brooks,  there  are  some  soli- 
tudes extending  southward  which  are  less  sterile  than  those  of  which  we 
have  just  spoken.  The  only  vegetation  which  some  of  these  exhibit  is  a 
few  scanty  brambles  here  and  there  creeping  over  the  ground;  others  are 
clothed  with  a  tliin  foliage  of  thorny  shrubs ;  but  the  greater  part  of  the 
bare  rocks  or  clay  in  these  desert  tracts  appears  just  the  same  as  when  it 
first  emerged  from  the  water.  Only  a  few  pitahayas^  like  gigantic  wax 
candles,  stand  solitarily  at  considerable  distances  from  each  other.  Their 
trunks,  which  rise  to  the  height  of  from  48  to  60  feet,  are  as  straight  as 
columns,  and  from  the  base  to  the  summit  have  a  nearly  uniform  thick- 
ness, equaling  sometimes  the  size  of  the  human  body ;  the  branches,  to 
the  number  of  two  or  three  only,  jut  out  from  the  trunk  at  a  right  angle, 
and  then  stand  erect,  like  the  branches  of.  an  enormous  candelabrum. 
Owing  to  the  regularity  of  their  shape,  their  parallel  sides  covered  with 
thorns,  and  their  grayish-green  color,  these  curious  plants  seem  to  be  a 
kind  of  intermediate  substance  between  the  tree  and  the  rock,  and  give 
to  the  landscape  an  aspect  which  is  both  fantastic  and  repulsive.  In  some 
regions  hundreds  of  miles  may  be  traversed  across  the  mountainous  val- 
leys and  plains,  and  during  the  whole  journey  no  other  species  of  terres- 
trial vitality  can  be  seen  but  these  immense  pitahayas.  Even  this  amount 
of  vegetation  is  wanting  in  the  most  sterile  districts  of  New  Mexico  and 
Arizona.  Thus  the  desert  of  Colorado,  situated  near  the  mouth  of  the 
river  bearing  the  same  name  in  the  Gulf  of  California,  is  a  totally  barren 
expanse  of  clay  and  sand.  In  the  evening,  when  the  sun  is  setting  far 
away  behind  the  ruddy  mountains  and  darting  its  rays  across  the  dusty 
atmosphere,  the  traveler,  when  encamped  in  the  bed  of  some  dried-up 
river  on  the  border  of  this  immense  plain,  which  was,  indeed,  formerly  a 
lake,  might  easily  fancy  that  he  sees  stretching  before  him  the  surface  of 
a  sea  of  fire.f 

The  deserts  of  North  America,  crossed  here  and  there  by  fertile  valleys, 
extend  eastward  toward  the  basins  of  the  Red  River  and  the  Arkansas, 
w'here  they  blend  with  the  savannas,  and  to  the  south  into  the  Mexican 
states  of  Chihuahua,  Sonora,  and  Sinaloa.  But  in  the  tropical  zone,  which 
commences  beyond  these  points,  the  heavy  summer  rains  and  the  much 
smaller  extent  of  the  Mexican  territory  between  the  two  oceans,  have  pre- 
vented the  foi*mation  of  deserts.  Regions  destitute  of  trees  and  verdure 
are  only  again  found  on  the  coasts  of  Peru,  to  the  south  of  the  Gulf  of 

*  Pacific  Railway  Report, — Jules  R^my,  Voyage  au  Pays  des  Mormons. 
t  Pacific  Railway  Report. 


104  THE  EARTH. 

Guayaquil.  The  trade-winds,  after  having  discharged  their  moisture  on 
the  eastern  slopes  of  the  Andes,  pass  away  through  the  air  far  above  the 
sea-shore  on  the  western  side  of  the  mountains,  and  then  sweep  far  out  to 
sea  over  the  surface  of  the  Pacific.  It  is  rarely  that  an  atmospheric  eddy 
blows  back  upon  these  coasts  even  the  smallest  rainy  current ;  sometimes 
five,  ten,  and  even  twenty  years  elapse  without  a  single  drop  of  rain  hav- 
ing fallen  in  Payta  and  the  other  sea-coast  towns.  The  greater  part  of 
the  houses  in  the  rich  and  commercial  city  pf  Iquique  were  sim'ply  com- 
posed of  four  walls,  without  the  useless  luxury  of  a  roof.  Nevertheless,  the 
coasts  of  Peru  are  not  completely  destitute  of  verdure.  Some  small  riv- 
ers, fed  by  the  snows  from  the  Andes,  and  tapped  throughout  their  whole 
length  by  irrigation-drains,  maintain  a  little  vegetation  in  the  valleys, 
and,  during  the  season  which  is  called  winter,  particularly  in  May,  June, 
and  July,  heavy  dews  refresh  the  soil  of  the  mountains  on  the  coast,  and 
cause  the  cactus  and  various  bulbous  plants  to  shoot  forth  here  and  there ; 
hence  is  derived  the  name  of  tietnpo  de  floras  given  to  this  part  of  the 
year.*  The  commercial  towns  situated  on  the  sea-shore,  the  gardens  in 
the  valleys,  the  rare  grasses  on  the  hills,  and,  lastly,  the  cliflT-like  declivi- 
ties of  the  Andes,  which  rise,  ridge  after  ridge,  up  to  their  snowy  sum- 
mits, give  to  the  whole  landscape  an  animated  character  which  is  entirely 
wanting  in  the  deserts  of  North  America. 

The  solitudes  of  the  Andes  most  resembling  the  desert  regions  of  the 
Old  World  and  of  the  United  States  are  the  elongated  plateaux  which 
rise  one  above  another  between  the  sea  and  the  principal  chain  of  the  An- 
des, in  southern  Peru  and  on  the  frontiers  of  Bolivia  and  Chili ;  such  as 
the  pampas  of  Islay  and  Tamarugal  and  the  desert  of  Atacama.  The 
pampa  of  Tamarugal,  so  called  fi*om  the  Tamariigos,  or  tamarisks,  which 
grow  in  the  hollows  where  some  moisture  oozes  out  of  the  soil,  has  a  mean 
altitude  of  from  2900  to  3900  feet.  It  is  a  plain  nearly  covered  with  beds 
of  salt,  or  salares,  which  are  worked  like  rock  quarries.  The  strata  of  salt 
are  so  thick,  and  rain  is  so  rare  upon  the  plateau,  that  the  houses  of  the 
village  of  Noria,  which  are  inhabited  by  the  workmen,  are  entirely  con- 
structed of  blocks  of  salt.  Some  deserts,  situated  to  the  east  of  the  Tam- 
arugal, on  more  elevated  plateaux,  contain  a  still  larger  quantity  of  salt. 
The  pampa  of  Sal,  which  is  overlooked  by  the  volcano  of  Isluga,  has  a 
mean  altitude  of  not  less  than  13,800  feet,  and  its  whole  extent,  which  is 
125  miles  long  and  from  nine  to  twenty-four  miles  wide,  is  perfectly  white. 
The  depth  of  salt  deposited  upon  this  plateau  varies  from  five  to  sixteen 
inches,  according  to  the  undulations  of  the  ground. 

Whence  do  these  enormous  masses  of  salt  proceed  ?  Doubtless  from 
the  sea  or  ancient  lakes  which  formerly  covered  these  countries  and  have 
been  gradually  emptied  by  the  rising  of  the  soil.  Saline  matter  saturates 
even  the  rocks  and  clays,  for  a  film  of  salt  again  forms  by  efflorescence 
on  all  the  ground  in  the  desert  from  which  crops  have  previously  been 
taken.     The  district  of  Santa-Rosa,  which  was  completely  cleared  of  salt 

*  Bollaert,  Antiquities. 


DESERT  OF  ATACAMA.  1  Qo 

ill  1827,  was  all  white  again  and  fit  for  working  after  a  lapse  of  twenty- 
three  years.  Sea-salt  is  not  the  only  production  of  these  immense  natural 
laboratories ;  but  nitrates,  sulphates,  carbonate  of  soda,  borates  of  soda 
and  lime,  are  also  found  there  and  increase  every  year  in  thickness,  thanks 
to  the  ephemeral  torrents  which  sometimes  descend  loaded  with  debris 
from  the  adjacent  Cordilleras.  Saltpetre  is  also  procured  from  the  pampa 
of  Tamarugal,  and  is  the  article  which,  during  all  the  wars  of  Europe  and 
America,  gave  such  great  commercial  importance  to  the  town  of  Iquique. 

About  the  middle  of  the  eighteenth  century,  an  Indian,  named  Negre- 
ros,  discovered  the  existence  of  saltpetre  in  the  pampa;  having  lighted  a 
fire  of  brush-wood  upon  the  soil,  he  perceived  that  the  ground  was  melt- 
ing, and  that  a  stream  issued  from  the  midst  of  the  firebrands  and  cinders. 
From  this  date  they  began  to  work  these  beds;  but  it  is  only  since  the 
last  fifteen  years  especially  that  this  branch  of  industry  has  been  carried 
on  to  any  considerable  extent.  According  to  Smith,  the  engineer,  the 
beds  of  nitrate  occupy  in  the  pampa  of  Tamarugal  an  area  of  483  square 
miles ;  in  some  spots,  where  the  mass  is  not  less  than  ten  feet  in  depth,  a 
ton  of  saltpetre  may  be  taken  from  a  square  yard  of  ground ;  but  reckon- 
ing only  on  a  product  of  110  lbs,  a  yard,  it  is  found  that  the  total  quantity 
of  saltpetre  at  present  contained  in  the  superfcial  beds  of  the  pampa  is 
not  less  than  sixty-three  millions  of  tons,  or  enough  to  supply  the  require- 
ments of  trade  for  1393  years,  if  the  working  does  not  exceed,  on  an  av- 
erage, that  of  the  year  I860.* 

The  desert  of  Atacama,  the  largest  of  all  those  in  South  America,  occu- 
pies a  wide  belt  of  plateaux  between  the  shores  of  the  Pacific  and  the 
high  rampart  of  the  Andes,  which  separates  Bolivia  from  the  Argentine 
Republic,  This  expanse  of  reddish -colored  rocks,  and  crescent -shaped 
shifting  sand-hills,  is  so  repulsively  desolate  a  place  that  the  conquerors 
of  Chili,  whether  Incas  or  Spaniards,  never  made  up  their  minds  to  ven- 
ture into  it,  in  going  along  the  sea-coast ;  they  have  been  obliged  to  pass 
far  into  the  interior,  by  the  plateaux  of  Bolivia,  and  to  twice  cross  the 
Andes  before  entering  the  Chilian  valleys.  Not  long  since,  men  of  sci-» 
ence  were  the  only  travelers  who  dared  to  enter  the  desert  of  Atacama. 
Nevertheless  this  formidable  -  looking  country  also  possesses,  like  the 
pampa  of  Tamarugal,  great  natural  riches,  which  will  not  fail  to  summon 
the  labor  of  man  and  all  the  progress  of  civilization  to  these  desolate  re- 
gions. Besides  salt  and  saltpetre,  this  desert  produces  guanof — that  is, 
heaps  of  the  almost  exhaustless  droppings  of  all  the  searbirds  which  set- 
tle down  in  clouds  upon  the  sea-shore.  During  the  course  of  centuries 
the  ordure  has  accumulated  into  perfect  rocks  which  the  sun  dries  up, 
and  the  surface  of  which  is  but  rarely  softened  by  rain.  These  masses 
of  detrittis,  which  are,  to  all  appearance,  useless  upon  these  barren  shores, 
are  life  itself  to  the  countries  of  England,  France,  and  Belgium,  which 
have  become  exhausted  by  the  extent  of  cultivation ;  and,  consequently, 
this  substance  constitutes  a  most  important  element  of  national  com- 
*  Bollaert,  Antiquities,  pp.  155,  240.  t  Derived  from  the  word  huanu. 


IQQ  THE  EARTH. 

merce.  The  principal  treasure,  or  national  bank,  so  to  speak,  of  the  Pe- 
ravian  Republic  is  represented  by  the  heaps  of  excrement  which  cover 
the  Chincha  Islands,  off  the  coast  of  Callao.  According  to  the  various 
calculations,  from  twelve  to  fifteen  millions  of  tons  of  excellent  guano  are 
to  be  found  there,  a  quantity  which  is  worth  to  Peru  more  than  eighty 
millions  of  pounds  sterling,  an  amount  which,  if  well  laid  out,  would  en- 
able the  happy  possessors  to  construct  a  magnificent  system  of  railways, 
and  to  build  a  school  in  each  of  their  villages.  But  they  must  be  quick 
about  it,  for  the  treasure  of  guano  will  probably  be  exhausted  in  twenty 
years;  already,  since  the  year  1866,  the  northern  island  has  been  cleared 
down  to  the  solid  rock. 


FLATS  AUK  AND  PLAINS.  IQT 


CHAPTER  XVII 

DIFFERENCE  BETWEEN  PLATEAUX  AND  PLAINS. — MATERIAL  IMPORTANCE 
OF  PLATEAUX  IN  .THE  ECONOMY  OF  THE  GLOBE. — DISTRIBUTION  OF  ELE- 
VATED  REGIONS   ON  THE   SURFACE    OF   CONTINENTS. 

XoTwiTHSTANDiNG  the  Variety  of  aspects  and  vegetation  which  is  in- 
troduced by  the  difference  of  climate,  low-lying  lands,  among  which,  it 
must  be  remembered,  are  included  so  many  sterile  deserts,  play  a  much 
less  important  part  in  the  history  of  the  globe  than  the  more  elevated 
portions  of  the  emerged  surface  of  the  earth.  Both  the  organization  and 
the  vitality,  so  to  speak,  of  continents  are  owing  to  the  external  relief  of 
the  planet ;  these  inequalities  in  the  surface  are  also  th6  cause  of  the  va- 
ried development  and  distribution  of  climates,  water-courses,  products, 
and  populations  over  the  whole  world. 

All  the  elevated  portions  of  continents  and  islands  may  be  naturally 
divided,  according  to  the  height  and  inclination  of  the  land,  ijjto  plateaux 
and  mountain  systems.  By  the  word  plateau  we  now  usually  undei*stand 
some  extent  of  land  raised  to  a  considerable  elevation  above  the  level  of 
the  sea ;  but  the  surface  is  not  always  uniform  and  level,  as  the  name 
would  seem  to  indicate.  When  the  surface  is  very  irregular,  either  fur- 
rowed by  deep  ravines,  or  dotted  over  with  hills  and  mountains,  the  ideal 
plain  which  would  pass  through  the  bases  of  all  the  mountains  at  a  height 
to  allow  for  filling  up  all  the  intervening  depressions  is  considered  as  the 
superficies  of  the  plateau.  There  are,  however,  some  plateaux  which  are 
almost  perfectly  level,  such  as  the  staked-plains  of  Texas  and  some  por- 
tions of  the  Utah  basin. 

Low-lying  lands,  also,  very  often  present  a  surface  undulated  with  hills 
and  valleys,  and  connected  with  higher  plateaux  either  by  gradual  slopes, 
or  by  a  succession  of  terraces,  which  may  be  looked  upon  either  as  the 
rise  of  the  plain  or  the  descent  of  the  plateau.  The  difference  existing 
between  high  and  low  lands  is  purely  relative ;  we  can  only  define  them 
by  saying  that  a  plain  is  a  surface  comparatively  level,  and  commanded  on 
one  or  all  sides  by  more  elevated  tracts,  and  that  plateaux  exceed  in 
height  the  land  surrounding  them.  The  ground  which  would  be  a  plain 
for  the  inhabitants  of  the  mountains  above  it,  would  be  a  plateau  for 
those  who  live  on  a  lower  level.  Thus,  in  I^ouisiana,  where  the  surface  is 
so  frequently  inundated,  undulations  of  the  ground  which  are  almost  im- 
perceptible to  the  eye  go  by  the  name  of  hills,  because  they  are  not  in- 
vaded by  the  floods  of  water ;  also,  on  the  level  surface  of  the  sea,  the 
blocks  of  ice  detached  from  the  glaciere  of  Greenland  and  Spitzbergen 
are  commonly  called  mountains  of  ice,  or  icebergs.     Agassiz,  when  con- 


108  THE  EARTH. 

templating  the  heights  of  Obydos,  in  the  midst  of  the  interminable  plains 
of  the  Amazon,  fancied  that  he  was  again  looking  upon  the  sublime 
mountains  of  his  native  country.* 

The  absolute  height  of  the  several  stages  of  elevation  of  the  land  is  not, 
therefore,  the  chief  thing  taken  into  account  in  the  geograpliical  division 
into  plains  and  plateaux,  but  the  relation  which  they  bear  to  the  conti- 
nental mass  of  which  they  form  a  part.  The  country  of  North  Hindostan 
is  more  elevated  than  the  plateaux  of  Suabia  and  Bavaria,  and  yet  it  must 
nevertheless  be  considered  as  a  plain,  because  it  belongs  to  a  continent 
the  general  features  of  which  are  gigantic,  in  comparison  with  those  of 
Europe.  In  both  parts  of  the  world  the  respective  proportions  are  re- 
tained between  the  various  stages  of  the  continental  edifice.  The  pla- 
teaux of  Asia  correspond  to  those  of  Southern  Gerniany;  the  Himalayas 
remind  us  of  the  Alps ;  Hindostan,  with  its  plains  amd  mountains,  is  the 
counterpart  of  the  Italian  peninsula. 

Although  plateaux,  precisely  on  account  of  their  size  and  the  grandeur 
of  their  proportions,  make  less  impression  on  the  human  mind  than  a 
steep  and  rugged  mountain  chain,  towering  up  between  two  countries 
like  an  enormous  rampart,  nevertheless  in  their  importance  in  the  vitality 
of  the  globe  they  are  certainly  superior  to  any  other  features  in  the  con- 
tinental configuration.  If  the  emerged  surface  of  the  planet  were  perfect- 
ly level,  the  most  dispiriting  uniformity  would  every  where  reign.  The 
same  phenomena  would  be  produced  over  the  whole  extent  of  the  conti- 
nental surface  from  one  ocean  to  the  other ;  the  winds,  meeting  with  no 
obstacle  in  their  course,  would  sweep  round  the  globe  w'ith  an  ever-equal 
motion,  like  the  long  bands  of  cloud  which  the  telescope  discovers  on  the 
planet  Jupiter.  There  would  be  none  of  those  elevated  masses  which,  by 
their  transverse  position  to  the  natural  course  of  the  winds,  produce  an  in- 
terruption of'the  equilibrium,  and  drive  back  the  atmospheric  currents  in 
every  direction.  There  would  be  none  of  those  great  refrigerators,  as 
they  may  be  called,  which  condense  the  moisture  in  the  clouds,  storing  it 
in  their  reservoirs  of  ice  and  snow.  Rain  would  fall  every  where  to 
nearly  an  equal  extent,  and  the  water,  finding  no  declivity  along  which 
it  might  be  carried  ofi"  to  the  ocean,  would  stagnate  in  putrid  marshes.  A 
perfect  equilibrium  of  the  forces  of  nature  would  have  as  its  effect  uni- 
versal stagnation  and  death.  Supposing  that  men  could  exist  on  such  an 
earth  as  this,  the  uniformity  of  one  great  plain  would  be  far  from  afford- 
ing them  any  greater  facilities  for  mutual  coramunicatiori ;  they  would, 
on  the  contrary,  remain  scattered  round  their  miserable  lagoons  in  all 
their  primitive  barbarism.  The  migrations  of  whole  nations  down  the 
inviting  slope  of  some  of  the^vast  continental  plateaux,  in  quest  of  a  new 
country,  like  a  great  river  seeking  the  sea,  could  never  have  taken  place. 
All  civilization  would  have  been  impossible.  Perhaps,  as  some  geologists 
think,  the  surface  of  the  globe  was  uniform  and  without  any  prominent 
relief  when  the  Icthyosaurus  swam  heavily  through  the  marsh-pools  and 
*  Conversafoes  sohre  o  Amazonas. 


PLATEAUX  AND  PLAINS.  109 

the  Pterodactyl  spread  his  sluggish  wings  over  the  reed-beds,  ^t  was 
then  an  earth  for  reptiles,  it  could  not  be  a  world  for  men. 

If  the  great  plateaux  of  the  globe  had  been  arranged  round  the  Arctic 
Frozen  Ocean,  and  their  long  slopes  had  gradually  sunk  toward  the  In- 
dian and  Pacific  oceans,  the  full  developpient  of  humanity  would  have 
been  equally  impossible.  In  the  north  the  altitude  of  the  plateaux  would 
have  doubled  the  cold  of  the  frozen  zone ;  all  organic  life,  even  that  of 
the  most  rudimentary  plants,  would  have  probably  ceased  to  exist,  and, 
doubtless,  the  freezing  winds,  sweeping  down  from  this  citadel  of  snows, 
would  have  changed  into  a  second  region  of  ice  those  temperate  countries 
which  are  now  the  fields  of  so  many  varied  products,  and  where  so  many 
powerful  nations  have  taken  their  rise.  The  only  habitable  lands  would 
be  the  islands  of  the  South  Seas  and  the  tropical  regions  of  the  continents, 
if,  indeed,  man  could  exist  at  all  in  a  climate  where  overwhelming  heat 
would  be  succeeded  by  icy  winds  blowing  down  from  the  lofty  plateaux 
of  the  north.  But,  even  supposing  that  isolated  tribes  could  have  found  a 
footing  in  these  countries,  mankind  in  a  general  sense  could  not  have  ex- 
isted ;  for  by  the  word  mankind  we  must  not  understand  merely  a  multi- 
tude of  scattered  individuals,  but  the  whole  human  race,  having  a  full 
self-consciousness  and  knowledge  of  its  destiny. 

Whatever  may  have  been  the  geological  causes  of  the  present  distribu- 
tion of  plateaux  over  the  various  continents,  the  following  remarkable 
fact  must  be  recognized,  that  their  height  increases  in  proportion  to  their 
proximity  to  the  torrid  zone,  as  if  the  rotation  of  the  globe  had  caused, 
not  only  the  equatorial  enlargement  of  the  planetary  mass,  but  also  the 
elevation  of  the  continents  themselves.  In  the  Tropic  of  Cancer,  the 
mean  altitude  of  the  plateaux  is  nearly  equal  to  that  of  the  mountains  in 
the  temperate  zone,  while  the  plateaux  of  the  latter  are,  on  the  average, 
the  same  height  as  the  mountains  of  the  polar  zone.*  In  consequence  of 
this  distribution  of  the  various  high  lands,  it  comes  to  pass  tfiat,  in  every 
latitude,  certain  portions  of  each  continent  exhibit  an  epitome  of  all  the 
climates  which  succeed  one  another  over  the  circumference  of  the  planet 
from  this  latitude  to  the  poles^  Owing  to  these  plateaux  and  the  mount- 
ains which  crown  them,  the  Iberian  peninsula,  Turkey,  and  Asia  Minor 
enjoy,  at  various  points  of  their  surface,  all  the  varieties  of  a  temperate 
climate,  and  thrust  their  loftiest  peaks  into  cold  regions  almost  similar  to 
those  of  the  poles.  In  countries  of  this  sort,  the  traveler  can  change  both 
the  climate  and  the  features  of  nature  round  him  by  a  journey  of  a  few 
days,  or  even  sometimes  of  a  few  hours ;  while  at  sea,  he  must  have  made 
a  voyage  from  the  tropics  to  the  icebergs  of  the  poles  if  he  wislied  to 
traverse  the  corresponding  stages  of  climate.  The  fact  of  the  gradually 
increasing  elevation  of  plateaux  as  we  go  south  tends  actually  to  double 
the  number  of  the  zones  in  the  middle  latitudes.  A  polar  climate  is,  as  it 
were,  placed  above  the  temperate  climate.  In  Hindostan,  three  zones  of 
temperature  merge  into  each  other  on  the  slopes  of  the  Himalaya,  the 

*  Metcalfe. 


110  THE  EARTH. 

lofty  southern  boundary  of  the  Asiatic  plateaux.  The  plains  beneath, 
where  vast  rivers  flow  down  to  the  sea  and  impenetrable  forests  extend 
over  vast  tracts,  are  inhabited  by  an  almost  innumerable  population; 
higher  up,  we  find  mountain  torrents,  long  avenues  of  firs,  and  flocks 
wandering  over  wide  pastures;, higher  still,  there  is  little  but  brushwood, 
mosses,  snow,  and  masses  of  ice.*  The  function  of  these  high 'lands  in 
the  economy  of  the  globe  is  to  bring  down  the  north  into  the  very  bosom 
of  the  south,  and  to  unite  within  a  limited  space  all  the  climates  of  our 
planet  and  all  the  seasons  of  the  year.  All  these  plateaux  are,  so  to 
speak,  small  continents  emerging  from  the  midst  of  the  plains,  and,  like 
the  great  continents  bounded  by  the  ocean,  their  phenomena,  as  a  whole, 
present  a  kind  of  epitome  of  the  phenomena  of  the  entire  globe ;  they 
may,  in  fact,  be  called  so  many  microcosms.  Vital  centres,  as  they  are, 
of  the  planetary  organism,  they  arrest  the  winds  and  the  clouds  in  their 
courses,  and,  discharging  the  rain,  modify  all  the  movements  which  take 
place  on  the  surface  of  the  globe.  Owing  to  the  circulation  of  elements 
which  is  incessantly  taking  place  between  all  the  more  prominent  por- 
tions of  the  continental  relief  and  the  two  oceans  of  the  atmosphere  and 
the  water,  the  gradations  of  climate  on  the  sides  of  the  plateaux  are  di- 
versely blended,  and  are  constantly  bringing  into  mutual  connection  both 
the  Flora  and  Fauna  of  every  country,  and  also  different  nations  and 
races  of  men. 

*  Vide  the  chapter  on  "The  Earth  and  its  Flora."' 


THE  GREA  T  PL  A  TEA  UX  OF  CEXTRAL  ASIA.  \ll 


CHAPTER  XVm. 

TIIE    GREAT    PLATEAUX    OF  CENTRAL  ASIA  AND   THE  GATE    OF  THE    HINDOO- 

KUTCU. PLATEAUX   OF  EUROPE  ;   THEIR  SYMMETRICAL  ARRANGEMENT. — 

PLATEAUX    OF  THE   TVVO    AMERICAS. — SIMILARITY    BETWEEN   THE    CLOSED 
BASIN    OF   BOLIVIA   AND   THE    DISTRICT   OF  UTAH. — PLATEAUX    OF  AFRICA. 

Plateaux,  like  the  continents  themselves,  exhibit  an  organization  more 
or  less  rudimentary,  and  a  shape  more  or  less  articulated,  and  therefore 
their  importance  as  agents  in  the  vitality  of  the  globe  proportionately  va- 
ries. Thus  the  great  plateaux  of  Central  Asia,  which  may  be  looked  upon 
as  the  very  skeleton  of  the  continent,  exercise,  it  is  true,  an  influence  of 
the  very  highest  order  in  the  general  economy  of  the  earth,  but  they  are 
almost  cut  off  from  all  the  rest  of  the  world ;  their  water-courses  run  into 
inland  basins,  without  any  outlet  to  the  sea,  and  the  nations  which  inhabit 
them  live  in  a  state  of  almost  perfect  isolation  from  the  other  peoples  of 
the  earth.  The  principal  group  of  plateaux,  which  is  bounded  on  the 
south  by  the  mountains  of  Karakoinim  and  Kuenlun,  on  the  west  by  the 
Bolor,  on  the  north  by  the  Thian-Chan,  the  Altai,  and  the  Daurian  Moun- 
tains, and  on  the  east  by  the  solitudes  of  the  great  Mongolian  desert  and 
the  variously  ramified  mountain  chains  of  the  interior  of  China,  constitute 
an  immense  quadrilateral  nearly  equal  in  extent  to  the  whole  of  Europe. 
Among  these  elevated  ranges  there  are  some,  as  the  Dapsang  and  the 
Boullon,  resting  upon  the  Kuenlun,  which  exceed  16,400  feet  in  mean 
height.*  Round  the  greatest  part  of  its  extent  this  enormous  fortress  of 
plateaux  is  rendered  almost  inaccessible  by  its  formidable  girdle  of  moun- 
tains, snows,  and  deserts ;  only  toward  the  northwest,  between  the  Thian- 
Chan  and  the  Altai',  several  depressions  in  the  surface  open  out  a  road 
through  which,  some  centuries  back,  the  terrible  Mogul  horsemen  poured 
down  to  enter  upon  their  course  of  devastation  through  Asia  Minor  and 
Eastern  Europe. 

At  one  of  its  angles,  the  great  quadrilateral  plateau  of  Central  Asia 
borders  upon  another  elevated  tract,  of  smaller  dimensions  but  of  nearly 
similar  shape ;  this  is  the  territory  of  Iran,  which,  although  likewise  in 
great  part  made  up  of  deserts,  does  not  form  so  much  of  a  prison  to  the 
people  who  inhabit  it  as  the  high  grounds  situated  more  to  the  east.  On 
the  north  it  has  several  outlets  toward  the  plains  of  Tartary  and  the  Cas- 
pian Sea,  on  the  west  toward  the  valleys  of  the  Tigris  and  Euphrates,  and 
also  is  connected  with  the  mountain-systems  of  Asia  Minor — the  long- 
reaching  peninsula  pushed  out  between  the  two  European  seas.  It  is  a 
remarkable  thing  that  just  in  the  very  vicinity  of  the  central  knot  of 

*  Schlagintweit. 


112  ^^^  EARTH. 

mountains  where  the  two  great  plateaux-systems  of  Mongolia  and  Iran 
are  united,  the  principal  portal  of  the  Aryan  nations  is  situated — the  de- 
file through  which  passed  the  flux  and  reflux  of  wars,  migration,  and  com- 
merce. By  a  singular  geographical  contrast,  this  vital  knot  of  the  conti- 
nent of  Asia  is  at  the  same  time  both  the  spot  where  th6  two  great  pla- 
teaux join  one  another,  and  also  where  the  plains  of  Hindostan  communi- 
cate with  those  of  Tartary  and  the  Caspian.  The  diagonals  both  of  the 
high  and  low-lying  lands  of  Asia  cross  at  right  angles  on  this  point  of  the 
Hindu-Kutch.*  Here  too  is  found,  as  regards  the  history  of  mankind,  the 
most  remarkable  spot  of  the  whole  earth. 

In  Europe,  too,  the  arrangement  of  the  most  considerable  plateaux  also 
exhibits  a  singular  symmetry.  In  the  same  way  as  in  the  continent  of 
Asia,  all  of  them,  with  the  exception  of  the  narrow  plateau  of  Southern 
Norway,  are  situated  in  the  south  of  Europe,  and  bounded  on  one  side  by 
a  chain  of  mountains.  On  the  west  there  is  the  plateau  of  Spain,  backed 
up  by  the  great  rampart  of  the  Pyrenees,  the  mean  height  of  the  plateau 
being  about  1980  feet;  in  Central  Europe  there  is  the  plateau  of  Suabia 
and  Bavaria,  commanded  on  the  south  by  the  lofty  Alps  of  Switzerland 
and  the  Tyrol ;  on  the  east  there  are  the  high  lands  of  Turkey,  situated 
all  along  the  southern  base  of  the  Balkan  range.  Thus  the  central  pla- 
teau of  the  three  extends  northward  from  a  system  of  mountains,  whilst, 
by  a  kind  of  polarity,  the  two  others,  situated  at  the  two  extremities  of 
Europe,  are  at  the  south  of  the  range  which  serves  as  their  base  of  sup- 
port.f  These  elevated  districts  are,  moreover,  much  more  richly  organ- 
ized than  those  of  Asia,  and  call  to  mind  the  form  of  the  continent  of 
which  they  form  a  part,  indented  as  it  is  with  its  numerous  bays  and  pen- 
insulas. These  plateaux  also  possess  their  promontories,  Avhich  push  out 
far  into  the  plains ;  wide  valleys,  too,  break  a  way  into  their  elevated  lev- 
els, thus  providing  numerous  outlets  to  the  peoples  which  inhabit  the  body 
of  the  plateau  and  the  country  surrounding  it.  By  means  of  their  diver- 
sified outlines,  the  elevated  countries  of  Europe  are  in  no  way  isolated 
from  the  rest  of  the  continent ;  in  no  place  are  the  rivers  compelled  to  ac- 
cumulate in  stagnant  lakes ;  every  drop  of  water,  every  product  of  the 
soil,  and  every  man  that  dwells  there,  can  find  an  easy  pathway  to  the 
surrounding  plains. 

As  a  type  of  those  elevated  tracts,  the  edges  of  which  are  very  sharply 
defined  by  steep  ramparts  which,  however,  thanks  to  the  valleys  which  cut 
into  them,  are  in  no  way  like  inaccessible  fortresses,  we  may  mention  the 
Cav^ses,  or  the  limestone  masses  of  southern  France.  In  the  region  of 
the  Jura,  similar  plateaux,  especially  that  of  Nantua,  have  been  cut  out 
by  the  water  with  so  much  regularity  that  one  involuntarily  thinks  of 
the  legendary  giants  who  used  to  cleave  mountains  with  a  blow  of  their 
swords. 

The  plateaux  of  the  two  Americas  are  of  much  greater  altitude  than 
those  of  Europe,  and  thus  correspond  to  the  continents  on  which  they 
*  Carl  Hitter,  Erdhmde.  t  Carl  Ritter,  Europa. ' 


PLATEAUX  OF  THE  TWO  AMERICAS. 


113 


Stand.  With  the  exception  of  the  secondary  plateaax  of  the  Alleghanies, 
the  Guianas,  and  Brazil,  all  the  elevated  tracts  of  land  in  America  are 
comprised  between  the  various  ramifications  of  the  mountain  chains  which 
rise  up  in  the  far  west  in  the  vicinity  of  the  Pacific.  The  plateau  of  Utah, 
or  the  "  Great  Basin,"  is  a  vast  territory,  the  outline  of  which  is  of  a  bold 
character,  and  guarded  by  parallel  ramparts  of  rocks ;  it  is  bounded  on 


Fig.  23.  The  Canssade — Department  Tarn  et  Garonne. 


one  side  by  the  foot  of  the  Rocky  Mountains,  on  the  other  by  that  of  the 
Sierra  Nevada ;  it  is  the  principal  vertebra  of  the  back-bone  of  the  conti- 
nent. 

Farther  to  the  south  extend  the  plateauk  of  New  Mexico,  Arizona,  Chi- 
huahua, and  La  Sonora,  all  alike  surrounded  by  mountains,  and  intersected 
with  ravines  and  valleys.  The  table-land  of  Anahuac,  the  enormous  cita- 
del which  towers  up  between  the  two  seas,  is  commanded  by  the  peaks 
of  Popocatepetl,  Cofre  de  Perote,  and  Orizaba.     Next,  beyond  the  Isth- 

H 


114 


THE  EARTH, 


mus  of  Tehuantepec,  we  meet  with  various  smaller  plateaux — those  of 
Guatemala,  Honduras,  Salvador,  and  Costa-  Rica — which  are  all  based  on 
ranges  of  mountains  partly  volcanic.  Their  respective  heights  correspond 
in  a  general  way  with  the  greater  or  less  width  of  their  base,  which  is 
bathed  on  one  side  by  the  Pacific,  and  on  the  other  by  the  Caribbean  Sea. 


Fig.  24.  Indented  Plateau  of  Nantua— Department  Ain. 


On  the  south  of  the  Gulf  of  Darien  we  have  a  series  of  high  plateaux 
commencing  with  the  enormous  chain  of  the  Andes.  In  every  place  where 
this  lofty  chain  divides  into  two  forks,  or  spreads  out  its  ridges  in  a  fan- 
like shape,  it  includes  between  the  mountain  spurs  a  plateau  of  4500,  6000, 
or  sometimes  even  as  much  as  1 2,000  feet  in  altitude. 

In  Columbia  we  have  the  plateaux  of  Pasto,  Antioquia,  Cundinamarca, 
and  Caraccas.     Farther  south,  the  two  chains  of  the  Andes  and  the  Cor- 


PLATEAUX  OF  AMEItlGA  AXD  AFRICA.  115 

dilleras,  which  separate  and  then  unite  only  to  divide  again,  include  be- 
tween their  snowy  ridges  the  plateaux  of  Quito,  Cerro  de  Pasco,  Cuzco, 
and  Titicaca,  and  lean  laterally  on  the  high  desei't  tracts  of  Atacama,  be- 
tween Bolivia  and  Chili,  also  on  the  hilly  terraces  of  Cuyo,  westward  of 
the  Argentine  joamjoaa.  Of  all  the  South  American  plateaux,  there  is  but 
one  which  is  so  completely  shut  in  by  the  rising  ground  i-ound  it  that  it 
is  unable  to  discharge  its  collection  of  rain-water  into  the  plains  below. 
This  is  the  plateau  of  Titicaca;  its  mean  elevation  is  not  less  than  13,200 
feet,  and,  from  its  height  and  extent,  forms  the  most  prominent  feature  in 
the  profile  of  the  Columbian  Continent.  This  Bolivian  plateau  is  the 
counterpart  of  the  "  Great  Basin"  of  North  America.  These  two  corre- 
sponding regions  both  alike  occupy  the  central  portion  of  their  respective 
continents,  each  being  about  1860  miles  from  the  isthmus  of  Central 
America ;  they  are  also  both  situated  between  the  forked  extensions  of  a 
great  system  of  mountains,  and,  in  the  depressions  of  their  surface,  con- 
tain lakes  without  any  outlet  to  the  sea. 

Geographically  speaking,  these  countries  are  as  if  isolated  from  the  rest 
of  the  world.  It  is  with  great  difficulty  that  the  semi-barbarous  inhab- 
itants of  Bolivia  are  able  to  enjoy  any  of  the  intercourse  of  commerce  or 
civilization  with  the  other  American  republics  or  the  countries  of  Europe. 
The  plateau  of  Utah  is  the  spot  where  the  Mormons  have  established  their 
settlement  in  order  to  escape  the  pressure  of  their  fellow-countrymen 
round  them ;  a  full  measure  of  the  North  American  energy  must  indeed 
have  been  necessary  for  pursuing  the  youthful  theocratic  community  into 
the  deserts  which  protected  them.  The  plateaux  which  witnessed  the  de- 
velopment of  the  autochthonous  civilization  of  the  Aztecs,  the  Toltecs,  the 
Guatimaltecs,  the  Muyscas,  the  Chibchas,  and  the  Incas,  have  one  immense 
advantage  over  the  closed-up  basins  of  Utah  and  Bolivia — they  communi- 
cate freely  with  the  sea-shore  by  means  of  their  open  valleys  and  the 
courses  of  their  rivers. 

The  African  plateaux  are  still  more  isolated  from  the  rest  of  the  world 
than  the  corresponding  tracts  of  land  in  America;  but  it  is  not  on  account 


Fig.  SB.  Section  of  Africa  from  Cape  de  Verde  to  Tadjara. 


of  their  great  height,  or  the  perpendicular  cliffs  of  the  mountains  which 
command  them ;  the  cause  is  rather  to  be  attributed  to  the  conditions  of 
their  climate,  and  to  the  situation  of  the  continent  itself.  The  greater 
part  of  the  elevated  regions  in  Africa  are  but  of  comparatively  low  eleva- 
tion, and  their  slopes  afford  an  easy  means  of  access.     The  plateaux  of  the 


IIQ  THE  EARTH. 

Cape  Colony,  the  mean  height  of  which,  on  the  south,  is  scarcely  660  feet, 
gradually  rise  toward  the  north  up  to  the  desert  of  Kalahari,  at  an  eleva- 
tion varying  from  2000  to  3000  feet  above  the  level  of  the  sea.  All  that 
we  at  present  know  of  the  interior  of  Africa  fully  warrants  us  in  thinking 
that  the  average  height  of  the  plateaux  increases  but  very  slightly  as  we 
approach  the  equator.  In  the  very  centre  of  the  continent,  the  region  of 
lakes,  whence  the  Nile  derives  its  source,  does  not  present  an  elevation  of 
more  than  4000  to  4600  feet ;  also,  in  the  north  of  Africa,  the  plateaux  of 
Morocco  and  Algeria,  along  almost  their  whole  extent,  are  below  3000 
feet  in  height.  The  most  remarkable  plateau  on  the  continent  is  that  of 
Ethiopia,  over  the  entire  extent  of  which — about  750  miles — a  mean  alti- 
tude is  maintained  of  7000  to  8000  feet.  The  steepest  escarpments  of 
this  mass  of  land  are  turned  toward  the  sea,  as  if  to  defend  the  Abyssin- 
ians  from  any  attacks  on  the  part  of  foreign  nations.  But  the  descent  on 
the  opposite  or  northwest  side,  in  the  direction  of  the  Nile,  is  twenty  times 
more  gradual ;  and  at  this  point  Abyssinia  would  be  easily  accessible,  if 
it  were  not  that  by  the  desert  character  of  the  country,  the  incessant  con- 
flict of  tribe  with  tribe,  and  the  miseries  of  the  slave-trade,  any  way  of 
access  to  its  frontiers  is  sown  thickly  with  perils.  Although  the  African 
continent  is  the  least  known  of  all  the  great  divisions  of  the  world,  and  is 
also  inhabited  by  the  most  barbarous  races  of  men,  yet,  taken  as  a  whole, 
as  regards  its  means  of  access  to  the  intercourses  of  trade  and  civilization, 
the  natural  obstacles  which  it  offers  are  not  to  be  compared  with  those 
presented  by  the  mountainous  walls  of  the  plateaux  of  Central  Asia  and 
of  the  Andes.  In  the  distribution  of  its  mountain  ranges,  its  elevated 
tracts,  its  plains  and  its  deserts,  and  also  in  the  general  outline  of  its 
coasts,  Africa  reminds  one  of  the  peninsula  of  Hindostan ;  it  is  an  India 
magnified  eleven  fold,  but  is  much  less  beautiful  and  well  shaped  than  the 
wonderful  Asiatic  peninsula. 


ISOLATED  MOUNTAINS.  \yj 


CHAPTER  XIX. 

ISOLATED  MOUNTAINS. — MOUNTAINS  IN  GROUPS. — CHAINS  AND  SYSTEMS  OF 
MOUNTAINS. — THE  BEAUTY  OF  MOUNTAIN  PEAKS. — SACKED  MOUNTAINS. 
— PLEASUEES  OP  MOUNTAIN  CLIMBERS. 

Although  mountains  do  not  play  nearly  so  important  a  part  as  pla- 
teaux in  the  economy  of  the  globe,  they  are,  nevertheless,  much  better 
known,  on  account  both  of  the  majesty  of  their  appearance  and  the  sharp 
contrast  which  they  present  to  the  country  round  them,  and  also  of  the 
variety  of  the  phenomena  of  which  they  are  the  scene  of  action.  Moun- 
tains which  tower  up  in  solitary  greatness  either  from  the  bosom  of  the 
sea  or  from  some  level  plain,  produce,  more  than  all  others,  an  effect  of 
the  highest  grandeur,  and  make  the  most  vivid  and  durable  impression 
on  the  mind.  The  mind's  eye  can  hardly  picture  scenes  superior  in  beau- 
ty to  those  formed  by  the  gracefully  undulating  slopes  and  purple  sum- 
mits of  solitary  mountains  like  the  Ventoux,  Etna,  the  volcano  of  Tene- 
riffe,  Orizaba,  and  so  many  other  peaks,  at  the  base  of  which  a  whole  ho- 
rizon seems  spread  out.  Some  of  those  heights  which  in  mountainous 
countries  would  scarcely  deserve  to  receive  a  name,  and  would  be  hardly 
looked  upon  as  hills,  make  pretensions  to  be  formidable  peaks  when  they 
spring  from  the  midst  of  a  level  plain,  or  on  the  edge  of  the  sea.  This 
applies  to  a  little  hill  of  about  780  feet  in  height  which  stands  in  the  cen- 
tre of  the  monotonously  level  districts  of  Lower  Pomerania ;  this  hill  has 
seemed  so  prodigious  to  the  inhabitants  of  the  country,  on  account  of 
the  savage  wildness  of  its  cliffs,  that  they  have  given  it  the  name  of  the 
"Mountain  of  Hell"  {HoUenberg).  In  the  same  way,  a  ridge  in  Denmark, 
which  rises  to  about  557  feet  in  height  above  the  level  of  the  sea,  has  been 
called  the  "  Mountain  of  Heaven"  {Himmelberg) :  it  is  an  Olympus,  like 
that  of  Greece. 

With  the  exception  of  volcanic  cones,  there  are  but  very  few  solitary 
mountains  which  rise  by  themselves  in  the  midst  of  a  level  country.  In 
almost  all  the  countries  of  the  world — in  those  at  least  which  possess  an 
at  all  strongly-defined  relief — we  meet  with  summits  in  considerable  num- 
ber, either  arranged  in  groups  or  in  long  ranges.  Generally  those  moun- 
tains which  are  grouped  in  the  form  of  a  circle  surround  a  more  elevated 
central  summit,  and  are  also  themselves  surrounded  by  heights  of  a  sec- 
ondary class,  which  abut  upon  lateral  buttresses,  and  gradually  sink  down 
to  the  level  of  the  plain  surrounding  them.  As  instances  of  this  sort,  we 
may  mention  the  group  of  the  Hartz  Mountains  in  Germany,  Mount  Fer- 
rat  in  Piedmont,  Sinai  in  the  Arabian  peninsula,  the  lofty  cluster  of  the 
Sierra-Nevada  of  Santa  Marta,  which  towers  up  to  a  height  of  19,680  feet 


113  T^^  EARTH. 

in  an  insular  tract  bounded  by  the  sea,  the  marshes,  and  the  deep  valleys 
of  the  Rio-Cesar  and  the  Rancheria.  The  chains,  properly  so  called,  which 
are  always  distinguished  by  a  considerable  development  of  the  length  of 
the  upheaved  ground,  sometimes  also  have  a  dominant  peak  as  their  cen- 
tral culmination,  on  each  side  of  which  the  summits  of  the  ridge  become 
gradually  lower ;  but  there  is  no  range  where  this  regular  arrangement 
is  carried  out  with  any  thing  like  geometrical  regularity.  The  greater 
part  of  the  mountainous  upheavals  are  found  to  present  a  collection  of  clus- 
ters, chains,  and  subsidiary  chains,  variously  grouped,  in  which  a  long  pro- 
cess of  study  is  required  for  duly  ascertaining  the  direction  of  the  ridges. 
They  must  not  be  looked  upon  as  chains,  but  as  systems  of  mountains. 

Owing  to  the  diversified  character  exhibited  by  these  numerous  groups 
of  heights,  both  in  their  geological  origin,  the  composition  of  their  rocks, 
the  general  direction  of  their  axis,  the  position  of  their  peaks,  the  vegeta- 
tion which  clothes  them,  the  light  which  illumines  them,  and  the  atmos- 
pheric agents  which  waste  them,  every  mountain  is  distinguished  from  its 
neighbors  by  certain  characteristics  of  special  beauty.  From  this  very 
fact,  among  all  this  assemblage  of  summits,  every  peak,  whether  charming 
or  magnificent,  which  rears  its  ravined  sides  above  the  base  of  upheaval, 
assumes  an  appearance  of  independent  vitality,  as  if  it  enjoyed  a  distinct 
individuality.  The  sight  of  these  giants  towering  up  over  a  wide-spread 
horizon  exercises  a  perfect  fascination  over  the  minds  of  some  men,  and 
they  are  urged  by  a  kind  of  instinct,  often  quite  unreflecting,  to  bend  their 
steps  toward  the  mountain,  and  to  scale  its  acclivities.  Through  either 
the  grace  or  majesty  of  their  form,  their  bold  profile  standing  out  sharply 
against  the  clear  sky,  the  girdle  of  clouds  rolling  round  their  rocks  and 
their  forests,  and  their  incessant  variations  of  light  and  shade  gleaming 
through  their  ravines  and  recesses,  mountains  seem  to  assume  an  appear- 
ance of  personality,  and  one  is  almost  tempted  to  look  upon  their  rocky 
masses  as  beings  endowed  with  all  the  powers  of  vitality.  Every  moun- 
tain, the  summit  of  which  in  its  bold  tracery  stands  out  clear  from  the 
rest  of  the  mass,  seems  to  be  so  thoroughly  an  individual  by  itself,  that  in 
most  cases  a  name  has  been  given  to  it,  often  the  half-poetic  title  of  some 
hero  or  god ;  and,  in  every-day  language,  we  constantly  attribute  to  it 
even  human  qualities.  Mountains,  in  fact,  are  truly  enough  geographical 
individualities,  and,  by  the  mere  fact  of  their  position  in  the  midst  of 
plains,  they  modify  in  a  thousand  ways  the  climates  and  all  the  other  phe- 
nomena of  the  districts  round  them.  Farther,  do  they  not  exhibit  within 
>  limited  space  an  epitome  of  all  the  beauties  of  the  earth  ?  Various  de- 
grees of  climate  and  zones  of  vegetation  are  arranged  in  gradation  on 
their  slopes ;  there,  too,  we  may  embrace  in  one  comprehensive  glance  the 
most  diverse  features  of  the  earth's  vitality — cultivation,  meadows,  for- 
ests, ice,  and  snow ;  there,  at  eventide,  we  may  see  the  fading  radiance  of 
the  sunlight  illuming  the  lofty  peaks,  and  endowing  them  with  a  marvel- 
ous effect  of  transparency,  as  if  the  enormous  mass  were  but  a  rosy-col- 
ored drapery  floating  lightly  in  the  clear  sky. 


SA  CRED  MO  UNTAJNS.—CL  UBS.  119 

In  days  gone  by  the  people  used  to  worship  mountains,  or  at  least  ven- 
erate them  as  the  seats  of  their  divinities.  All  round  Merou,  the  proud 
throne  of  the  gods  of  India,  every  stage  of  humanity  may  measure  its  prog- 
ress by  the  side  of  other  sacred  mountains  where  the  lords  of  heaven  were 
wont  to  assemble,  and  where  all  the  great  mythological  epopees  of  the  life 
of  nations  have  been  brought  to  pass.  The  peak  of  Lofeu  in  China,  and 
the  volcano  of  Fusi-Yama  in  Japan,  are  both  sacred  mountains.  The  Sa- 
manala,  or  Adam's  Peak,  whence  can  be  enjoyed  a  view  full  of  grandeur 
over  the  well- wooded  valleys  of  Ceylon,  is  also  reverenced  as  a  holy  spot; 
and  on  its  loftiest  peak  stands  a  wooden  temple,  fastened  down  to  the 
granite  mass  by  chains  imbedded  in  the  fissures  of  the  rock.  This,  ac- 
cording to  the  Mohammedan  and  Jewish  legend,  is  the  spot  on  which 
Adam,  driven  out  of  the  earthly  paradise,  came  to  do  penance  for  many  a 
long  century;  here,  too,  the  divine  Buddha  left  the  mark  of  his  footprint 
when  he  took  flight  to  soar  up  into  heaven.  To  the  Armenians,  Mount 
Ararat  is  no  less  sacred  than  the  Samanala  is  to  the  Buddhists,  or  the 
peak  which  towers  over  the  sources  of  the  Ganges  is  to  the  Hindoos.  It 
was  on  one  of  the  rocks  of  the  Caucasus  that  Prometheus  was  bound  down 
in  punishment  for  having  stolen  the  fire  of  heaven.  For  many  an  age 
Mount  Etna  was  the  citadel  of  the  Titans ;  the  three  brows  of  Olympus, 
which  proudly  rear  their  dome-like  forms,  were  the  magnificent  dwelling- 
places  of  the  gods  of  Greece,  and  when  a  poet  wished  to  invoke  Apollo, 
he  turned  his  supplicating  glance  to  the  summit  of  Parnassus.  If  the  pol- 
ished Hellenes  thus  venerated  the  mountains  of  their  native  country,  how 
great  must  be  the  adoration  which  would  be  paid  by  ignorant  barbarians 
to  the  mountain  which  bore  upon  its  terraced  ledges  their  miserable  huts, 
much  as  a  forest-tree  carries  a  bird's-nest  on  its  spreading-branches  !  I'he 
mountain  which  affords  them  shelter  seems  to  them  to  reign  far  and  wide 
over  the  earth,  and  in  it  they  proudly  recognize  their  father  and  their  god. 

In  our  day  we  have  certainly  ceased  to  worship  mountains ;  but,  at  all 
events,  those  that  know  them  best  seem  to  love  them  with  a  perfect  love.* 
To  scale  the  loftiest  summits  has  at  the  present  time  become  a  complete 
passion  ;  every  year  important  ascents  are  made  by  thousands,  independ- 
ently of  the  minor  expeditions  which  travelers  undertake  to  the  summits 
of  a  secondary  class  and  of  easy  access.  Alpine  Clubs,  or  societies  of 
mountain-climbers,  composed  in  great  part  of  some  of  the  most  energetic 
and  most  intelligent  savants  of  Western  Europe,  have  devoted  themselves 
to  the  task  of  vanquishing,  one  after  another,  every  mountain-top  which 
had  been  hitherto  considered  inaccessible ;  they  carry  away  from  them  a 
stone  as  an  emblem  of  their  triumph,  and  they  leave  on  them  a  thermom- 
eter, or  other  scientific  instrument,  in  order  to  facilitate  the  investigations 
of  any  bold  climber  who  may  follow  them.  The  Alpine  Clubs  have  drawn 
up  a  list  of  all  the  peaks  which  are  still  rebellious,  and  have  fully  discussed 
the  means  of  subduing  them;  they  have  also  investigated  multitudes  of 
ascents,  and,  by  their  charts,  their  descriptions,  and  their  numerous  meet- 

*  Vide  Mountaineering,  by  Tyndnll,  and  the  various  publications  of  the  Alpine  Clubs. 


120  2!HiE'  EARTH. 

ings,  they  have  largely  contributed  in  throwing  light  on  the  architecture 
of  the  Alps.  The  collected  traveling  journals  of  the  members  of  these  va- 
rious clubs  are  unquestionably  the  source  from  which  the  most  valuable 
information  may  be  derived  as  to  the  rocks  and  glaciers  of  the  loftiest 
mountaifas  in  Europe,  and  they  also  give  us  the  most  interesting  narratives 
of  difficult  ascents.  In  the  far-distant  future,  when  not  only  the  Alps,  but 
also  all  the  other  accessible  summits  in  the  world,  have  become  perfectly 
familiar,  the  records  of  the  Alpine  Clubs  will  form  the  Iliad  of  mountain- 
climbers  ;  and  people  will  talk  of  the  exploits  of  a  Tyndall,  a  Tuckett,  a 
Coaz,  a  Theobald,  and  of  other  heroes  of  this  grand  epopee  of  Alpine  con- 
quest, just  as  the  exploits  of  noted  warriors  were  once  the  subjects  of  song. 
Whence  proceeds  the  deep-seated  joy  which  is  felt  in  scaling  a  lofty 
summit?  In  the  first  place,  there  is  a  great  physical  pleasure  in  breath- 
ing the  fresh  keen  air,  which  has  never  been  vitiated  by  the  impure  ema- 
nations of  the  plains.  Man  feels  renovated  by  merely  tasting  this  atmos- 
phere of  life ;  the  higher  he  mounts  up,  the  more  rarefied  becomes  the 
air ;  deeper  inspirations  are  necessary  to  fill  the  lungs,  the  chest  is  swelled, 
the  muscles  are  at  full  stretch,  a  cheerful  flow  of  spirits  pervades  the  mind. 
The  pedestrian  who  scales  a  mountain  feels  himself  his  own  master,  and 
responsible  for  his  own  life ;  he  is  not  delivered  over  to  the  capriciousness 
of  the  elements,  like  the  navigator  who  trusts  his  fortunes  to  the  sea ; 
much  less  is  he  like  the  railway  traveler — a  mere  human  package — paid 
for,  ticketed,  and  put  in  a  carriage,  and  then  dispatched  at  a  fixed  time, 
under  the  surveillance  of  employes  in  uniform.  On  alighting,  he  regains 
the  use  of  his  limbs  and  his  liberty.  His  eye  enables  him  to  avoid  the 
stones  that  lie  in  his  path,  to  measure  the  depths  of  precipices,  and  to  dis- 
cover the  rocky  projections  and  clefts  which  will  facilitate  the  escalade 
of  the  cliffs.  The  force  and  elasticity  of  his  muscles  will  enable  him  to 
leap  over  safely  the  deepest  crevasses,  to  maintain  his  footing  on  the  steep- 
est inclines,  and  to  raise  himself,  step  by  step,  up  the  most  difficult  pas- 
sages. On  a  thousand  occasions  during  the  ascent  of  a  steep  mountain, 
he  must  fully  recognize  that  he  is  running  a  fearful  danger  should  he  ei- 
ther chance  to  lose  his  balance,  or  allow  a  sensation  of  giddiness  to  dim 
his  sight,  even  for  an  instant,  or  should  his  limbs  refuse  their  wonted  serv- 
ice. This  consciousness  of  peril,  joined  to  the  pleasurable  knowledge  of 
his  activity  and  health,  is  the  very  sensation  which,  in  the  mind  of  the 
pedestrian,  doubles  his  feeling  of  safety.  With  what  joy  does  he  after- 
ward relate  the  slightest  incident  of  the  ascent — the  stones  rolling  down 
the  mountain  slope,  and  plunging  into  the  torrent  beneath  with  a  dead- 
ened sound ;  the  root  to  which  he  hung  suspended  when  he  scaled  a  wall 
of  rock ;  the  streamlet  of  snow-water  at  which  he  quenched  his  thirst ;  the 
first  glacier  crevasse  over  the  brink  of  which  he  stooped,  and  yet  dared  to 
leap ;  the  long  and  weary  slope  up  which  he  so  painfully  climbed,  with 
his  legs  buried  knee-deep  in  the  snow ;  finally,  the  culminating  peak  from 
which  he  saw,  spreading  away  into  the  mist  of  the  horizon,  the  immense 
panorama  of  mountain,  valley,  and  plain.     When  the  traveler  looks  back 


TUM  ASCENT  OF  MOUNTAINS.  121 

from  afar  upon  the  summit  which  he  conquered  at  the  cost  of  so  much 
exertion,  it  is  with  perfect  rapture  that  he  sees  it  again,  or  traces  out  with 
his  glance  the  path  that  he  followed,  from  the  valleys  at  its  base  to  its 
snow-clad  peak.  The  mountain  seems  actually  to  look  down  and  smile 
upon  him  from  afar ;  for  him  alone  its  snow  glitters,  and  the  fading  sun- 
light illumines  it  with  his  last  ray. 

With  regard  to  the  intellectual  pleasure  which  mountain  climbing  af- 
fords, which,  however,  is  intimately  bound  up  with  the  material  joys  of 
the  ascent,  it  is  proportionately  greater  as  the  ftiind  is  more  expanded,  and 
the  various  phenomena  of  nature  have  been  more  successfully  studied. 
The  destructive  action  of  water  and  snow  is  fully  grasped  by  the  scientific 
traveler ;  he  inspects  the  movement  of  the  glaciers,  and  the  rolling  rocks 
or  boulders  making  their  way  from  the  summits  to  the  plain ;  he  traces 
out  the  enormous  horizontal  or  inclined  strata;  he  perceives  the  masses 
of  granite  upheaving  the  beds ;  then,  when  he  at  last  stands  on  some  lofty 
peak,  he  can  contemplate  in  its  entirety  the  mountain  edifice,  with  its  ra- 
vines and  its  spure,  its  snows,  its  forests,  and  its  meadows.  The  hollows 
and  the  valleys  which  the  ice,  the  water,  and  the  tempest  have  carved  in 
the  immense  relief,  are  clearly  defined,  and  the  whole  labor  accomplished 
during  thousands  of  centuries  by  all  the  geological  agents  is  plainly  seen. 
By  going  to  the  origin  of  the  mountains  themselves,  a  surer  judgment  can 
be  passed  on  the  various  hypotheses  of  savants  as  to  the  rupture  of  the 
earth's  crust,  the  displacement  of  strata,  and  the  eruption  of  granite  or 
porphyry.  And  besides,  without  alluding  to  that  meaner  impulse  of  van- 
ity which  instigates  a  certain  number  of  men  to  distinguish  themselves  as 
mountain-climbers,  there  is  a  sentiment  of  natural  pride  excited  when  we 
compare  our  own  littleness  with  the  grandeur  of  the  natural  phenomena 
which  surrounds  us.  The  torrent,  the  rocks,  the  avalanches,  and  the  gla- 
ciers, all  remind  man  of  his  own  weakness;  but,  by  a  natural  reaction,  his 
intellect  and  his  will  rise  up  in  opposition  to  every  obstacle.  He  takes  a 
pleasure  in  conquering  the  mountain  which  seems  to  brave  him,  and  in 
proclaiming  himself  the  victor  over  the  formidable  peak,  the  first  glance 
at  which  had  filled  his  mind  with  a  kind  of  religious  awe. 

Owing  to  the  increasing  facilities  of  communication,  and  to  the  love  of 
nature  so  much  developed  in  modern  society — owing,  too,  to  the  example 
which  has  been  set  by  bold  mountain-climbers,  the  elevated  regions  of  cen- 
tral Europe,  where  once  but  few  travelers  cared  to  venture,  on  account  of 
the  want  of  roads,  the  steepness  of  the  inclines,  the  danger  from  avalanch- 
es, and  the  dread  of  the  unknown,  are  nowadays  become  the  great  centre 
of  popular  attraction.  These  very  mountains,  so  difficult  of  access,  which 
tower  up  as  a  rampart  between  the  north  and  south  of  Europe,  have  caused 
Switzerland  to  become  the  great  rendezvous  of  nations ;  and,  during  the 
season  for  traveling,  bathing,  and  mountain-climbing,  it  enjoys  a  floating 
population  of  some  hundreds  of  thousands — a  number  which  increases  ev- 
ery year.  Vevay,  Lucerne,  and  Interlacken  are  like  sacred  cities  to  which 
every  lover  of  nature  must  pay  his  pilgrimage. 


122  ^^^  EARTH. 


CPIAPTER  XX. 

VARIOUS    FORMS    OF   MOUir^INS. POVERTY    OF    POLISHED    LAKGUAGES    US 

DESCRIBING    THEIR   APPEARANCE. RICHNESS    IN    THIS    RESPECT    OF    THE 

SPANISH  LANGUAGE  AND  THE  ALPINE  AND  PYRENEAN  PATOIS. THE  NU- 
MEROUS PROVINCIAL  TERMS  EMPLOYED  FOR  VARIOUS  SHAPES  OF  HILLS 
AND   MOUNTAINS. 

Mountains  vary  singularly  in  their  shapes,  according  to  their  height, 
their  geological  constitution,  and  the  force  and  direction  of  the  meteoric 
agencies  that  assail  them ;  so  vast  is  the  multitude  of  causes,  in  great  part 
unknown,  which  have  labored  either  in  concert  or  in  succession  in  carving 
out  these  projections  of  the  earth,  that  every  peak  has  its  own  special  as- 
pect. It  would  thus  seem  almost  necessary  to  employ  a  particular  desig- 
nation, if  not  for  every  mountain,  at  least  for  each  of  the  types  to  which 
we  may  be  able  to  reduce  the  numerous  shapes  of  the  earth's  protuber- 
ances. Unfortunately,  our  languages  manifest  a  remarkable  poverty  in 
words  well  fitted  to  bring  before  the  mind's  eye  the  precise  outlines  of 
any  particular  summit.  Whatever  may  be  the  appearance  of  two  or  more 
mountains  and  the  geological  composition  of  their  rocks,  the  geographer 
and  the  author  are  compelled  to  avail  themselves  of  the  same  terms  in 
designating  them,  unless,  indeed,  they  have  recourse  to  a  long  description 
in  cases  where  a  single  word  ought  to  suffice.  They  are,  in  fact,  obliged 
to  make  use  of  words  altogether  unsuitable,  such  as  the  term  "  chain," 
which  is  invariably  applied  to  ranges  of  hills. 

The  cause  for  this  penury  in  exact  geographical  terms  may  be  very  eas- 
ily understood.  Most  of  the  cities  in  which  the  various  languages  were 
gradually  refined  are  situated  on  very  level  ground,  or  among  hills  very 
slightly  undulated.  There  can  be  no  doubt  but  that  the  French  nomen- 
clature in  respect  to  mountains  would  have  been  much  richer  and  more 
exact  if,  from  Blois,  Paris,  and  Orleans,  lofty  peaks  had  beeu  visible  in  the 
horizon.  The  richness  and  the  propriety  of  the  terms  employed  by  the 
southern  Germans,  the  Spaniards,  and  Italians,  when  they  wish  to  describe 
in  one  word  various  kinds  of  hills  and  mountains,  are  certainly  derived 
from  the  fact  that  these  nations  have  lived  and  formed  their  language  in 
full  view  of  lofty  summits.  M.  de  Humboldt,  in  his  Tableau  de  la  Nature, 
quotes  the  following  terms  employed  by  Castilian  authors :  pico,pioacho, 
mogote,  eucurucho,  espigon,  loma,  tendicla,  niesa,panecillo,/arallon,  tablon, 
peiia,  pefion,  penasco,  pefloleria,  roca  partida,  laja,  cerro^  sierra^  serrania, 
Cordillera,  monte,  montana,  montanuela,  altos,  malpais,  reventazon,  htifa, 
etc. — all  of  which  serve  to  designate  the  diverse  forms  of  mountains,  or 


TEE  FORMS  OF  MOUNTAINS. 


123 


chains  of  mountains.  It  would  be  easy  to  still  further  enlarge  this  long 
list  of  names. 

The  inhabitants  of  the  Pyrenees  and  French  Alps  use  in  their  dialects  a 
great  variety  of  expressions,  each  of  which  is  especially  devoted  to  some 
particular  type  of  mountain,  and  consequently  serves  to  depict  to  the 
mind's  eye  a  perfectly  different  form.  Many  of  these  names,  inherited  from 
the  ancient  Celtic  and  Iberian  dialects,  well  deserve  to  be  admitted  into 
the  French  written  language,  the  more  so  that  they  are  in  customary  use 
by  all  the  French  mountaineers  from  the  sources  of  the  Rhone  to  the 
Pyrenees. 

In  the  Alps  of  Queyras  and  Viso,  lofty  peaks  with  escarped  sides  which 
tower  over  all  the  neighboring  summits  are  known  by  the  name  of  brie 
or  brec.  Of  this  kind  is  the  beautiful  pyramid-shaped  mountain  of  Cham- 
beyron  (11,112  feet  in  height),  which  rises  to  the  south  of  the  valley  of 
the  Ubaye,  in  the  midst  of  a  circle  of  pointed  summits  of  a  less  height. 


Pig.  26. 


"  Brie,"  or  Crest,  of  Monte  Vlso,  seen  from  the  East ;  after  TncketL 


Of  this  kind,  too,  is  the  Viso  itself,  at  least  on  its  northern  face,  for  the 
other  side  ofcthe  mountain  presents  too  regular  a  slope  to  entitle  it  to  the 
name  of  brie.  Above  the  upper  valley  of  the  Guil,  black  cliffs  rise  up,  fur- 
rowed by  avalanches,  then  an  enormous  tower-like  mass  with  perpendicu- 
lar sides,  and  at  last  the  truncated  peak  crowned  with  its  thick  covering 
of  snow.  The  apparently  inaccessible  terrace  which  so  proudly  overtops 
the  Col  de  Valante,  the  secondary  summits  of  Visoletto,  and  the  rocks  that 
have  toppled  down  from  the  heights — this  is  the  brie  of  the  Viso.  To  any 
mountaineer  who  has  never  set  eyes  upon  this  proud  summit,  this  term 
will  convey  far  more  meaning  than  the  vague  designation  of  "mountain." 
In  the  same  way,  the  old  term  pelve,  now  disused,  which,  however,  we  may 
still  recognize  in  the  names  of  the  Grand-Pelvoux,  the  Palavas,  the  Pelvas, 
the  Pelvo,  and  several  other  mountains  in  Dauphine,  at  once  depicted  to 
the  mind's  eye  an  enormous  cone  commanding  all  the  neighboring  sum- 
mits. 
The  tttcs  and  trues  of  the  Pyrenees  are  also  summits  of  lofty  elevation, 


124 


TEH  EARTH. 


but  not  the  highest  points  in  the  ridge ;  they  get  this  name  on  account  of 
the  bold  outline  of  their  upper  cliffs,  and  not  from  their  pre-eminence  over 
the  mountain-tops  round  them.  As  instances  of  these  tiics  we  may  cite 
those  of  Maupas,  Montarque,  and  Mauberme,  in  the  Central  Pyrenees. 

The  tuque,  the  truque,  the  tusse,  and  the  tausse,  all  specify  mountains 
with  wider  bases  and  more  gentle  slopes  than  those  of  the  tuc ;  but  now- 
adays these  picturesque  designations  have  been  gradually  displaced  by 
the  more  general  term  of  pic,  which  is  applied  without  distinction  to  all 
pointed  and  almost  inaccessible  summits.  It  is  a  curious  fact  that  the 
downs  on  the  Atlantic  sea-coast,  which  by  the  inhabitants  of  the  intermin- 
able level  of  the  French  Landes  are  looked  upon  as  real  mountains,  still 
retain  this  provincial  name  of  tucs,  although  it  has  fallen  into  disuse  for 
the  giants  of  the  Pyrenees.  A  few  miles  from  Arcachon,  a  down  of  about 
260  feet  high  has  made  such  an  impression  on  the  imagination  of  the  in- 
habitants of  the  Landes  that,  by  an  emphatic  pleonasm,  they  have  styled 
it  the  True  de  la  Truque. 

Those  very  steep  and  pointed  summits,  which  are  generally  designated 
by  the  exaggerated  but  rather  striking  name  of  aiguilles  (needles),  have, 
in  most  cases,  received  from  the  natives  of  the  district  much  less  ambitious 
appellations,  the  most  common  of  which  is  pic.  The  Pyrenees  also  include, 
among  some  of  their  highest  mountains,  several  piques ;  as  the  Pique 
Longue  duVignemale  (11,049  feet  high)  and  the  Pique  d'Estats  (10,104 
feet  high).  The  enormous  cluster  of  the  Alps  of  Pelvoux  has  for  its  cul- 
minating summit  a  pointed  peak  13,461  feet  high,  which  was  once  called 
the  Barre  des  JEcrins.  But  in  Savoy  and  French  Switzerland  summits  of 
this  form  are  principally  known  by  the  name  oi  dent  (tooth),  almost  sy- 
nonymous with  the  designation  horn,  which  is  used  in  Central  Switzerland, 
starting  from  Mont  Cervin  or  the  Matterhorn,*  that  boldly  modeled  mass 
which  Byron  looked  upon  as  his  ideal  type  of  a  mountain.  The  dents  are 
generally  less  pointed  than  the  aiguilles,  and  are  rounded  off  toward  the 


Fig.  27.  The  Pic  du  Midi  d'Ossan,  seen  from  the  northeast ;  after  V.  Petit. 
*  Coaz,  Alpejiclub,  vol.  ii. 


THE  FORMS  OF  MOUNTAINS.  125 

summit ;  but  the  transitions  presented  by  the  mountain  outlines  are  so 
gradual  that  it  is  difficult  to  establish  any  very  strict  classification.  Li 
consequence,  great  confusion  prevails  in  the  nomenclature,  and  the  greater 
part  of  the  summits  in  the  Swiss  Alps  bear  indiscriminately  the  name  of 
horn.  In  the  Tyrol,  too,  the  term  kogel  {kegel^  skittle)  is  applied  to  moun- 
tains of  the  most  diversified  shapes. 

The  four-sided  pyramids  which  spring  up  so  numerously  in  some  moun- 
tain ridges  are  called  the  caires,  queyres,  esquerras,  or  quairats  of  the  Alps 
and  Pyrenees.  Certain  peaks  of  this  kind  have  given  a  name  to  an  entire 
cluster  of  the  French  Alps — that  of  Queyras.     If  the  point  of  the  pyramid 


Kg.  28.  Einsborn  de  Splegen ;  after  Coaz. 

is  replaced  by  an  elongated  ridge,  the  mountain-top  then  becomes  a  tail- 
lante  (edge).  If,  on  the  contrary,  the  summit  terminates  in  a  cubical  mass, 
it  will  be  designated  by  the  name  tour  (tower).  Calcareous  mountain  re- 
gions are  the  localities  where  we  chiefly  find  those  enormous  quadrangu- 
lar layers  which  seem  as  if  they  had  been  built  in  by  the  Titans.  Few 
spectacles  in  Europe  are  equal  in  beauty  to  that  afibrded  by  a  view  from 
the  Pic  de  Bergons  over  the  limestone  region  of  the  Central  Pyrenees,  with 
its  perpendicular  walls,  its  snow-covered  terraces,  its  tower-like  heights, 
appearing  to  the  glance  almost  inaccessible,  and  its  carved-out  gaps,  like 
openings  purposely  made  between  battlements.  A  similar  appearance  is 
presented  by  the  calcareous  eminences  of  La  Clape,  near  Narbonne,  and 
by  the  sandstone  mountains  in  several  districts.  The  faces  of  these  per- 
pendicularly hewn  peaks  are  often  designated  by  the  very  appropriate 
names  parois  (side -walls),  or  pareds^  murs  (walls),  or  murailles  (ram- 
parts). 

Tower-like  peaks  of  comparatively  smaller  dimensions,  which  ajjpear  as 
if  they  were  edifices  built  on  the  mountain-tops,  have  received  in  the  Pyr- 
enees the  name  ofp^ne,  or  bovgn.  The  t^te  (head)  is  a  summit  with  regu- 
lar and  gently  inclined  terminal  slopes,  springing  up  from  a  mass  furnished 
Avith' steeper  sides.  If  the  roundness  of  the  summit  is  developed  in  the 
form  of  a  cupola,  the  mountain  is  then  a  sowm  (summit),  or  a  ddme^  as 
Mont  Blanc,  the  giant  of  Europe.  In  German  Switzerland  mountains  with 
flattened  summits,  as,  for  instance,  the  Rhigi,  are  known  by  the  name  of 
kulm.     In  the  Vosges  the  ballotis,  and  in  the  Black  Forest  the  bodcheriy 


126 


THE  EARTH. 


Fig.  29.  The  GroBS-Glockner ;  after  Payer. 

represent  mduntains  terminating  in  large  summits,  which  seem  blown  out 
in  the  shape  of  a  bladder.  The  bases  of  these  mountains  are  generally 
very  wide,  and  the  slopes  gently  inclined. 


Pig.  30.  L'Esquerra  des  Eaux-Bonnes,  seen  from  the  southwest;  after  V.  Petit. 

The  names  applied  to  summits  of  a  secondary  class  are  no  less  numerous 
than  those  given  to  the  principal  mountain-tops.  A  spur  connected  with 
a  rounded  summit  frequently  receives  in  the  Pyrenees  the  appellation  of 
turon^  or  turonnet ;  and  an  escarped  projection,  extending  with  saw-like 
indentations  {kamm^  in  German),  takes  the  name  of  serre,  or  some  deriva- 
tive of  it,  such  as  sarrat  or  serrhre  ;  it  is  the  Spanish  sierra  in  miniature. 

CyliT.dre  de  lC*rboro 

_W82  8.»i« 


Brjdic  leKolxnd 


Icfulloa 


deOavanue  Soum      d*Amp 

Pig.  31.  The  Monn tains  of  QavamJe,  seen  from  the  north :  after  V.  Petit 


NAMES  OF  MOUNTAIN  PEAKS. 


127 


A  motte  {muotta  in  the  Grisons)  is  a  mountain  almost  isolated  from  the 
rest  of  the  group,  or  even  rising  in  the  midst  of  a  valley  in  an  alluvial  dis- 
trict. Finally,  some  mountain  names  point  out  the  nature  of  their  rocks 
or  their  vegetation.  The  Lauzet  or  Lauzi^res  mountains  are  composed  of 
slaty  rocks,  and  in  the  Pyrenees  the  numerous  peaks  called  estiMre^  or 
pradhre^  are  completely  clothed  with  verdure.  The  words  puy,  puig,  pei/, 
pech^  or  ptch,  are  general  terms  which  are  applied  indiscriminately  to  all 
the  prominences  either  of  mountain  ridges  or  of  the  plain,  from  the  Puig 
de  Carlitte  (9563  feet  high)  down  to  the  smallest  elevations.  It  is  re- 
markable that  the  words  which,  in  our  more  classical  language,  are  most 
used  to  denote  elevations  of  the  surface,  namely,  montagiie  (mountain)  and 
coUine  (hill),  are  taken  in  quite  a  diffei'ent  acceptation  in  the  idioms  of  the 


■'C'?^ 


Fig.  32.  Pdne :  Piz  ii  Lnn  de  Onscha ;  after  Coaz. 

inhabitants  of  the  Pyrenees  and  Alps.    '"'■Montagn^^  means  only  a  greater 
or  less  extent  of  pasture-land,  and  the  terra  "  coUine'''  applies  to  the  dales 
lying  between  two  mountains. 
In  addition  to  the  names  employed  by  the  inhabitants  of  the  Alps  and 


Fig.  88.  Tete:  Wallenstock  de  Wolfenschiessen ;  after  Coaz. 

Pyrenees  to  specify  various  types  of  mountains,  we  must  mention  some 
which  are  made  use  of  in  the  French  tropical  colonies,  one  or  two  of  which, 
such  as  morne  and  pit07i,  have  found  their  way  into  literary  language.  In 
volcanic  countries,  the  mountains  of  igneous  origin,*  with  summits  round- 
*  Vide  the  chapter  on  "Volcanoes." 


128  ^^^  EARTH. 

ed  like  a  cupola,  like  the  Puy  de  Dome,  or  pierced  with  a  crater  like  the 
Puy  de  Sancy,  are  almost  all  designated  by  local  terms  of  very  striking 
aptitude ;  but  the  greater  part  of  these  words  remain  unknown  to  fame. 
Nothing  can  prove  more  decisively  how  much  modern  communities  still 
adopt  as  their  ideal  a  life  altogether  artificial,  and  without  sympathy  with 
nature.  Happily,  a  kind  of  reaction  is  steadily  setting  in.  Attracted  by 
the  beauty  of  the  summits  which  once  startled  them,  crowds  of  travelers 
now  find  their  way  to  the  mountains;  they  learn  to  know  them,  to  love 
them,  and  to  describe  them.  Thus  languages  are  enriched,  and  science 
gains  a  further  store  of  information. 


INEQUALITIES  AND  DEPRESSIONS  OF  MOUNTAINS.  129 


CHAPTER  XXI 

INEQUALITIES  AND  DEPRESSIONS  IN  THE  VERTICAL  OUTLINE  OF  MOUNTAINS. 
— ORIGIN  OF  VALLEYS,  GORGES,  AND  OTHER  DEPRESSIONS. — LONGITUDI- 
NAL VALLEYS. — ^TRANSVERSE  VALLEYS. — WINDING  VALLEYS  WITH  PAR- 
ALLEL  SIDES. — VALLEYS   WITH    DEFILES    AND   GRADATIONS    OF    LEVELS. 

CLUSES   AND   CANONS. —  GENERAL   ARRANGEMENT   OF   VALLEYS.  —  AMPHI- 
THEATRES.— THE   OULE8   OF  T^E   PYRENEES. 

Mere  height  constitutes  but  the  most  inconsiderable  element  in  the 
beauty  of  mountains:  the  majesty  as  w^  as  grace  of  their  appearance 
is  chiefly  due  to  the  distortions  and  dip  of  their  strata,  the  circular  dells 
and  glens  which  are  hollowed  out  upon  their  slopes,  their  yawning  de- 
files, their  abrupt  precipices,  and,  finally,  the  broad  valleys  stretched  out 
at  the  base  of  the  colossus,  which,  by  the  contrast  that  they  afibrd,  enable 
us  the  better  to  appreciate  the  magnificence  of  its  proportions.  Owing  to 
the  variety  of  outline  and  scenery  caused  by  all  these  successive  depres- 
sions, the  mountain  has  assumed  an  aspect  of  grandeur  and  life  which  it 
must  originally  have  wanted.  Like  a  block  of  marble  transfigured  by  the 
sculptor's  hand,  the  mighty  mass,  once  a  monotonous  plateau  or  mere  dome 
of  rock,  has  been  gradually  modified  by  meteoric  agents  incessantly  affect- 
ing it,  and  has  been  converted,  into  one  of  those  mountains,  in  the  proud 
profile  of  which  our  forefathers  recognized  the  face  of  a  god.  We  may 
easily  figure  to  ourselves  all  the  changes  which  have  been  effected  in  the 
form  of  mountains  by  the  various  depressions  of  the  soil,  if  we  visit  cer- 
tain groups  of  heights,  one  side  of  which  retains  its  old  plateau-like  as- 
pect, while  the  other,  sinking  abruptly  toward  the  plain,  has  all  the  ap- 
pearance of  an  actual  escarpment.  There  are  many  instances  of  this  kind. 
in  the  region  of  the  central  plateau  of  France,  of  Auvergne,  the  Jura  Moun- 
tains, the  Rauhe  Alp  in  Wtlrtemberg,  and  in  Bavaria.  On  one  side  stretch 
long  stony  slopes ;  the  fields  are  all  unfertile,  and  the  prospect  is  uniform, 
and  devoid  both  of  movement  and  life.  Then,  all  of  a  sudden,  as  we  attain 
the  edge  of  the  ridge,  we  see  opening  out  below  us  a  succession  of  decliv- 
ities :  hollows  filled  with  water  appear  between  the  escarpments  and  the 
fallen  rocks ;  farther  down  in  the  increasingly  misty  depths  we  catch  sight 
of  terraces  and  ledges  crowned  with  firs,  and  trickling  rivulets  glittering 
in  the  dells  at  the  base  of  the  cliffs.  Far  beneath  our  feet,  at  the  very 
bottom  of  the  gulf,  lies  the  peaceful  valley,  like  another  world,  with  its 
winding  river,  its  fields,  its  vineyards,  its  woods,  and  its  busy  towns. 

What,  then,  is  the  origin  of  the  valleys,  gorges,  ravines,  and  all  the  oth- 
er depressions  which  we  meet  with  in  the  elevated  regions  of  the  earth? 
This  is  a  question  which  must  be  considered  identical  with  an  inquiry  into 

I 


130  T^^  EARTH. 

the  origin  of  the  mountains  themselves,  a  point  on  which  geologists  are  as 
yet  very  far  from  having  come  to  any  agreement.  We  can  only  state,  in 
a  general  way,  that  some  of  these  depressions  are  primitive  features  of  the 
ancient  conformation  of  the  mountains,  and  owe  their  origin  either  to  dis- 
turbances of  the  strata  or  faults  in  the  rocks ;  others  have  been  gradually 
eaten  away  by  time,  or  hollowed  out  by  snow,  ice,  rain,  and  water-courses. 
Those  who  try  to  reconstruct  in  imagination  mountain  systems  as  they 
must  have  existed  in  preceding  ages  assert  with  certainty  that  some  val- 
leys were  contemporaneous  with  the  mountain  groups  which  surround 
them.  They  also  feel  warranted  in  boldly  declaring  that  this  glen  or  that 
ravine  was  cut  out  by  meteoric  agencies ;  but,  as  regards  a  considerable 
number  of  the  most  important  features  of  the  mountain,  doubt  still  con- 
tinues to  weigh  upon  their  minds. 

At  all  events,  when  extensive  longitudinal  valleys  are  included  between 
two  mountain  chains  which  a^Jparallel  to  each  other,  but  different  in  age 
and  geological  formation,  these  valleys  are  indisputably  of  primitive  ori- 
gin ;  they  are  the  hollow  of  the  terrestrial  crust  formed  naturally  by  the 
slopes  of  the  two  acclivities  which  rise  on  the  right  and  left.  The  whole 
length  of  the  valley  itself  must  have  been  upheaved  by  the  forces  which 
were  at  work  on  both  sides  of  it  under  the  adjacent  masses,  and  it  has 
also  been  variously  modified  during  the  lapse  of  ages  by  the  water-courses 
which  have  traversed  it.  In  one  place  its  hollows  have  been  filled  up,  in 
another  its  rocks  have  been  carried  away — the  water  having  deepened  it 
on  one  side  to  build  it  up  on  the  other.  But,  notwithstanding  all  its 
modifications,  the  geologist  none  the  less  recognizes  the  valley  to  have 
been  furrowed  out  in  the  same  age  as  that  in  which  the  neighboring  high 
mountain  summits  were  formed.  Thus  the  great  depression  of  the  lower 
Valais,  which  divides  the  peaks  of  the  Finsteraarhorn  and  the  Jungfrau 
from  those  of  Monte  Rosa  and  Mont  Blanc,  is  certainly  a  primitive  valley 
in  all  its  essential  features.  For  still  stronger  reasons,  the  vast  cavity  of 
the  Lake  of  Geneva,  which  bends  round  between  the  Alps  and  the  Jura 
Mountains,  the  lowest  depths  of  which  are  but  little  above  the  level  of 
the  sea,  must  have  had  an  existence  at  least  coeval  with  all  the  mountains 
of  Switzerland. 

Certain  transverse  valleys,  which  break  abruptly  through  a  mountain 
chain,  and,  as  it  were,  cut  it  in  two,  must  also  belong — at  least  most  of 
them — to  the  primitive  mountain  conformation.  Of  this  kind  is  the  charm- 
ing valley  of  Engadine,  the  slope  of  which  rises  almost  imperceptibly  up  to 
the  foot  of  the  Maloggia  (5941  feet),  above  which  towers,  7352  feet  higher, 
the  summit  of  the  Bernina.  In  the  New  Zealand  Alps,  Julius  Haast  dis- 
covered a  still  more  astonishing  transverse  valley,  as  the  foot  of  it,  com- 
manded on  both  sides  by  peaks  measuring  7800  and  9800  feet  in  height, 
was  only  at  an  altitude  of  1600  feet,  scarcely  one  fifth  of  the  height  of  the 
chain.  Finally,  in  all  the  mountain  ranges  composed  of  volcanic  cones 
upheaved  at  intervals  along  the  same  fissure  in  the  earth,  large  transverse 
valleys,  which  are,  in  reality,  the  remains  of  the  foimer  plain,  are  found  in 


ORIOm  OF  VALLEYS. 


131 


great  numbers.  This  may  be  especially  remarked  in  Java  and  in  the  Chil- 
ian Andes.* 

With  regard  to  the  ordinary  transverse  valleys  which  owe  their  origin 
to  some  depression  in  the  face  of  the  mountain,  and  merge  into  a  larger 
valley  or  into  a  plain,  being  connected  also  with  other  glens  which  open 
out  right  and  left  into  the  thickness  of  the  mountain,  it  is  always  difficult, 
and  often  impossible,  to  distinguish  between  the  effects  which  must  be  re- 
ferred to  the  action  of  water  and  those  which  are  to  be  ascribed  to  other 
causes  which  have  co-operated  in  the  formation  of  these  gigantic  furrows. 
Even  in  those  spots  where,  on  the  two  sides  of  the  valley,  the  layers  of 
rock  all  perfectly  correspond,  we  are  unable  to  tell  whether  the  original 
fissure  was  not  produced  by  a  natural  contraction  of  the  beds,  or  by  some 
sudden  movement  of  the  crust.  It  is,  however,  quite  sufficient  to  note  the 
geological  labor  accomplished  every  year  by  the  torrent  roaring  along  in 
its  deep  bed,  in  order  to  be  convinced  how  mighty  its  action  must  have 
been  duiing  an  immense  cycle  of  centuries,  f 

Buffon  has  established  the  fact  that  a  great  many  winding  mountain 
valleys  are,  from  their  origin  to  their  outlet,  walled  in  on  each  side  by 
parallel  escarpments.     The  projections  on  the  cliff  on  one  face  correspond 


Fig.  34.  Channel  of  the  Bosphorua. 


*  Vide  the  chapters  devoted  to  "  Rivers"  and  "Volcanoes." 
t  Vide  the  chapter  on  "  Rivers." 


232  ^^^  EARTH. 

with  the  hollows  on  the  other;  the  projecting  and  the  re-entering  angles 
alternate  on  either  side,  so  that  if  the  two  opposite  cliffs  were  suddenly 
brought  close  together,  their  windings  and  irregularities  would  mutually 
coincide.  Other  valleys,  however,  present  an  altogether  different  kind  of 
formation :  their  sides,  instead  of  running  regularly  in  parallel  curves, 
are  in  some  places  very  wide  apart,  in  others  very  close  together.  They 
thus  follow  a  kind  of  rhythm  very  different  to  that  of  the  first  type  of 
valley,  and  produce  a  succession  of  rounded  basins,  separated  from  each 
other  by  narrow  passes.  In  the  Pyrenees,  the  Jura,  and  the  calcareous 
regions  of  the  Alps,  valleys  of  this  kind  are  very  numerous ;  but  we  more 
often  observe  a  combination  of  the  two  modes  of  formation.  At  certain 
points  of  their  course,  valleys  run  tortuously  between  parallel  sides ;  at 
others,  they  form  successive  basins.  Thus  the  upper  portion  of  the  long 
channel  of  the  Bosphorus,  which  may  be  looked  upon  as  a  valley,  although 
now  invaded  by  the  waters  of  the  sea,  presents  several  stretches  of  water 
almost  like  lakes,  while  farther  down  the  channel  the  indentations  of  the 
opposite  banks  are  so  regularly  arranged  that  they  might  almost  be  fitted 
one  into  the  other. 

The  variations  in  the  shape  of  valleys  may  be  explained  by  the  different 
natures  of  the  rocks  which  the  waters  have  had  to  hollow  out.  Wherever 
the  material  operated  upon — gravel,  sandstone,  granites,  schists,  or  lavas 
— are  of  an  analogous  composition,  and  thus  every  where  present  an  equal 
amount  of  resistance  to  the  action  of  the  water,  the  latter  is  able  to  pur- 
sue its  normal  movement,  and  adopts  a  meandering  course,  which  ap- 
proaches each  bank  in  turn,  thus  communicating  the  windings  of  its  bed 
to  the  valley  it  is  hollowing  out.  On  the  contrary,  when  the  rocks  consist 
of  strata  of  unequal  hardness,  or  are  traversed  by  obstructing  walls,  the 
water  is  necessarily  compelled  to  spread  out  into  a  lake-like  accumulation, 
in  the  mean  time  eating  away  the  banks  in  a  lateral  direction,  until — the 
barrier  being  at  last  penetrated — the  sheet  of  water  is  poured  down  in  a 
torrent  to  some  lower  level.  In  this  way  there  has  been  formed,  during  a 
course  of  ages,  a  series  of  basins  one  above  the  other,  some  of  which  are 
still  partially  tilled  with  water,  others  entirely  empty,  all  being  linked  to- 
gether by  narrow  defiles,  through  which  pours  the  mountain  torrent.*  In- 
stances of  a  series  of  this  kind  of  small  basins  of  verdure,  arranged  like  a 
succession  of  steps,  are  very  numerous  in  all  mountainous  regions.  We 
may  mention  the  valley  of  Qo  in  the  Pyrenees,  and  in  the  Alps  the  lofty 
valley  of  Is6re,  in  which  old  lake-basins  and  gloomy  gorges  alternate  with 
great  regularity. 

The  various  channels  or  cuts  which  unite  the  various  basins,  and  through 
which  are  precipitated  the  impetuous  flood  of  the  mountain  torrent,  are 
called  in  the  Jura  by  the  name  of  cluses,  and  in  the  Alps  are  designated 
as  chts ;  but  in  these  countries  they  do  not  limit  themselves  to  cutting 
through  mere  barriers  of  rock — they  pierce  even  through  mountain  chains. 
The  basins  of  the  Var  and  its  water-courses  are  very  rich  in  defiles  of  this 
kind — enormous  incisions  carried  right  through  the  thickness  of  the  lime- 
•  Vide  the  chapters  devoted  to  "  Rivers"  and  *'  Lakes." 


CLUSE8  AND  CAMONS.  I33 


irw)i 
andN 


stone  ramparts.  Among  these  clus  there  ar^rome  which  are  really  fonni- 
dable — those  of  the  Loup,  between  Grasse  and  Nice ;  those  of  Saint  Auban 
and  the  Echaudan,  and  others  which  afford  a  passage  to  the  waters  of  the 
Var  Sol  its  tributaries.  These  are  tremendous  defiles ;  each  side  of  the 
torrent  is  walled  in  with  perpendicular  or  overhanging  rocks  several  hun- 
dred yards  high,  and  the  summit  of  the  escarpment  is  generally  crowned 
with  the  picturesque  walls  of  some  ancient  village.  These  narrow  gorges, 
through  which  it  is  often  found  difficult  to  carry  a  road  or  even  a  path, 
must  be  classed  among  the  most  curious  sights  in  France.  The  view  of 
these  gloomy  passes  is  all  the  more  striking  as  one  comes  upon  them  im- 
mediately after  traveling  over  the  fertile  plains  of  the  Mediterranean 
shores,  studded  with  villas,  gardens,  and  olive-groves.  The  clus  of  the 
Aube  and  its  tributaries,  those  of  the  Upper  Dordogne,  the  Tarn,  and  the 
Lot,  are  also  formidable  in  their  appearance ;  but  the  most  remarkable  in 
the  world  are  probably  the  canons  of  Mexico,  Texas,  and  the  Rocky  Moun- 
tains, in  which  we  see  a  river,  almost  without  water,  flowing  at  a  depth  of 
several  thousand  feet  between  perpendicular  walls.  According  to  New- 
berry, the  geologist,  the  great  cation  of  the  Colorado  is  not  less  than  298 
miles  in  length,  and  in  several  places  its  perpendicular  sides  rise  to  a 
height  of  3300,  5000,  and  60(^  feet. 

Li  accordance  with  the  size  of  the  mountains,  the  nature  of  their  rocks, 
the  abundance  of  their  snow  and  rainfall,  the  elevated  valleys  exhibit  the 
most  astonishing  diversity  of  shape  and  aspect.  In  clusters  of  mountains 
where  the  torrents  rush  down  to  the  plain  over  a  very  steep  bed,  and 
through  sharp  windings  hollowed  out  in  the  body  of  the  rocks,  most  of 
the  tributary  valleys,  opening  right  and  left  of  the  principal  ravine,  are 
constituted  altogether  like  the  latter,  except  perhaps  that  they  are  still 
more  winding,  and  the  water  in  them  runs  more  rapidly ;  these,  too,  re- 
ceive the  streams  of  smaller  glens  which  are  still  steeper  than  themselves. 
Generally  speaking,  every  tributary  vale  unites  with  the  central  valley  at 
the  precise  spot  where  the  latter  presents  the  convex  side  of  its  windings. 
The  result  is,  that  valleys  and  their  tributaries,  as  a  whole,  exhibit  an  ar- 
rangement which  is  very  similar  to  that  of  a  tree  with  a  succession  of 
branches.  In  calcareous  mountains,  where  the  torrents  run  through  a  se- 
ries of  basins  one  above  the  other,  and  communicate  by  means  of  cluseSy 
the  system  of  valleys  shows  a  more  rudimentary  arrangement.  In  this 
case,  each  basin  is  also  the  point  of  junction  for  two  lateral  valleys  oppo- 
site to  each  other,  and  ascending  in  a  straight  line  toward  the  heights  of 
the  mountain.  The  ensemble  of  all  these  symmetrical  depressions  reminds 
one  of  the  trees  in  gardens  which  are  trained  as  espaliers,  the  opposite 
branches  of  which  creep  along  their  supporters  in  parallel  lines. 

With  regard  to  the  dales,  glens,  ravines,  and  all  the  smaller  depressions 
of  a  mountain,  from  those  deep  gashes  which  legends  tell  us  were  made 
by  some  giant's  sword,  down  to  those  gentle  and  graceful  undulations 
which  resemble  the  folds  of  drapery,  their  variety  is  so  endless  that  it 
would  be  impossible  to  classify  them  in  any  systematic  order.  Each 
mountain,  having  its  own  peculiar  individuality,  differs  in  the  character 


134 


THE  EARTH. 


of  its  dales  and  glens,  whicnjjoo,  have  each  their  special  aspect  of  majesty 
or  ^race. 

Almost  every  valley  commences  with  a  kind  of  amphitheatre  of  greater 
or  less  extent,  hollowed  out  of  the  thickness  of  the  central  mass  of  the 
chain,  and  formed  by  the  union  of  the  ravines  and  gullies  of  the  surround- 
ing mountains.  The  amphitheatres  of  a  circular  or  elliptical  form,  which 
we  come  upon  all  on  a  sudden  after  having  wandered  along  winding  val- 
leys or  on  the  sides  of  perpendicular  cliffs,  form  a  beautiful  spectacle  in  all 
their  calm  and  peaceful  grandeur.     We  must  visit  the  calcareous  moun- 


Fig.  85,  Circular  Valley  of  Onrdinse. 

tain  chains,  such  as  the  Central  Pyrenees,  with  their  perpendicular  walls 
and  deeply-hollowed  basins,  if  we  wish  to  see  these  wonderful  amphithe- 
atres in  full  perfection.  The  most  remarkable,  on  account  of  their  vast 
dimensions  and  the  snow-clad  terraces  which  surround  them,  are  the  oules 
(boilers)  of  Gavamie,  Estaub6,  and  Troumouse,  which  the  slow  action  of 
centuries  has  hollowed  out  in  the  calcareous  sides  of  the  mountains  of 
Marbore.  Undulating  tracts  of  pasture-land  furrowed  by  torrents,  pro- 
digious walls  rising  to  1500,  or  even  2000  or  3000  feet  in  almost  perpen- 
dicular height,  gigantic  steps  on  which  whole  nations  might  find  room  to 
sit,  cascades  which  either  spread  out  over  the  precipice  and  float  away  in 
a  diaphanous  veil  of  mist  or  rush  down  into  the  valley  like  an  avalanche, 
the  high  summits,  glittering  with  unstained  snow,  which  rear  their  heads 
high  above  the  wall  of  cliffs,  as  if  to  look  over  into  the  inclosure — all  these 
features  we  find  combined  far  in  the  recesses  of  these  solitary  mountains, 
so  as  to  render  the  Pyrenean  amphitheatre  one  of  the  grandest  tableaux 
in  Europe. 


DEPRESSIONS  IN  MOUNTAIN  SILOES.  135 


CHAPTER  XXn. 

DEPRESSIONS   IN  MOUNTAIN   RIDGES. — DIVERSITY  IN  THE   FORM    OP   PASSES 
(cols). — RELATION    BETWEEN    THE    RESPECTIVE    ALTITUDES    OF   SUMMITS 

AND    PASSES. — LAW   OF   DEBOUCHMENTS. REAL   AND    IDEAL   SLOPES    OF 

MOUNTAINS. — ESTIMATED   SOLID   CONTENTS    OF   MOUNTAIN   GROUPS. 

Mountain  necks  or  passes  (cols) — that  is,  the  hollows  or  depressions  of 
the  ridge  or  summit,  are,  like  the  valleys,  to  be  attributed  to  diverse 
causes.  Some  are  primitive  features  produced  by  the  disturbance  or  rup- 
ture of  the  upheaved  beds ;  others  are  excavations  of  more  recent  origin, 
and  are  due  to  meteoric  action  and  the  crumbling  away  of  the  mountain 
mass. 

The  variety  of  causes  which  have  combined  in  the  formation  of  these 
depressions  sunk  into  the  ridges,  the  varying  force  of  resistance  offered-by 
different  rocks,  and  all  the  events  of  the  incessant  conflict  carried  on  for 
centuries  between  the  mountain  summits  and  the  air  which  surrounds 
them,  have  combined  in  giving  to  these  passes  the  greatest  diversity  of 
aspect.  Some  are  mere  turfy  or  snow-clad  bands,  between  two  rounded 
brows ;  others  are  themselves  narrow  ridges  of  sharp-edged  rocks,  com- 
manded on  each  side  by  pyramidal  masses;  these  zx&fourches  (forks)  and 
hourquettes  of  the  Pyrenees.  Others,  again,  are  deep  fissures  carved  out 
between  perpendicular  walls ;  some,  even,  like  huge  gateways  opening  be- 
tween the  valleys  from  opposite  sides,  are  actual  breaches,  which  we  should 
be  inclined  to  think  had  been  effected  in  the  living  rock  by  the  processes 
of  sapping  and  mining. 

It  has  often  been  asked  if  there  is  not  a  constant  analogy  between  the 
altitude  of  summits  and  that  of  the  passes  which  indent  their  ridges.  It 
might  easily  be  foreseen  that,  as  the  mountains  had  been  diveraely  worn 
away  by  the  effects  of  storms,  snows,  and  water,  the  depressions  of  the 
passes,  which  are  the  result  of  these  long-protracted  erosions,  must  be 
looked  for  at  various  elevations  in  the  different  groups.  This,  too,  has 
been  proved  by  M.William  Huber,  as  the  result  of  patient  comparative  in- 
vestigation. Thus,  in  the  group  of  Mont  Blanc,  the  proportion  between 
the  mean  height  of  the  summits  and  that  of  the  passes  is  as  1*28  to  1 ;  in 
the  Monte  Rosa  group  it  is  as  1'43  to  1 ;  in  the  Jungfrau  it  is  as  1*62  to  1. 
The  relation  between  the  highest  summit  and  the  lowest  pass  also  differs 
very  considerably  in  different  systems  of  mountains.  In  the  Todi  group 
this  proportion  is  as  2*68  to  1 ;  it  is  only  as  r53  to  1  in  the  Tessinese 
Alps.*  In  a  general  way,  the  altitude  of  the  widest  and  deepest  passes 
of  the  Alps  may  be  estimated  at  one  half  of  the  height  of  the  surrounding 
*  William  Huber,  Bulletin  de  la  Socictc  de  Geographie,  Febniaiy,  March,  1866. 


136  ^^^  EASTS. 

summits,  while  in  the  Pyrenees  it  is  about  two  thirds.  The  more  consid- 
erable depressions  which  divide  the  Alps  into  distinct  masses,  toward 
which  tend  a  quantity  of  secondary  passes,  give,  by  the  contrast  which 
they  afford,  a  peculiar  character  of  grandeur  and  variety  to  the  orographic 
system  of  Central  Europe.  The  Pyrenees  are  much  more  uniform  than 
the  Alps  in  their  architecture,  and,  in  consequence  of  the  relative  heights 
of  their  passes,  form  one  of  the  most  beautiful  types  of  the  Cordillera 
which  can  be  found  upon  the  earth. 

It  is  a  remarkable  fact,  brought  to  light  by  M.  Huber,  that  the  passes 
which  are  hollowed  out  the  most  deeply  in  the  mountain  mass  debouch 
precisely  in  front  of  the  most  elevated  peaks  of  the  opposite  group.  Thus 
the  pass  of  the  Simplon  (6594  feet)  opens  directly  in  front  of  the  group 
of  the  Jungfrau  (13,6'71  feet);  and  the  Gemmi  (7161  feet), the  least  ele- 
vated pass  in  the  Bernese  Alps,  debouches  in  the  valley  of  the  Rhone,  di- 
rectly in  front  of  Monte  Rosa  (15,216  feet).  In  the  same  way,  the  pass 
of  Lukmanier  (6289  feet)  faces  the  summit  of  Todi,  and  the  pass  of  the 
Julier  lies  in  the  axis  of  the  great  Bernina  group.  It  may,  in  fact,  be  no- 
ticed with  regard  to  nearly  all  the  principal  passes  that,  on  the  other 
side  of  the  valley,  they  are  fronted  by  one  of  the  highest  mountains  of 
the  divergent  chains  which  radiate  round  the  central  nucleus  of  the  St. 
Gothard. 

To  what  cause,  then,  are  we  to  attribute  this  general  situation  of  the 
principal  passes  to  which  M.  Huber  has  given  the  name  of  the  "  law  of  de- 
bouchments?" It  may  be  explained  in  great  part  by  the  fact  that  the 
most  elevated  mountainous  masses  generally  rest  on  the  widest  and  most 
solid  foundations ;  the  torrents,  consequently,  pass  round  their  bases,  while 
on  the  opposite  side  the  phenomenon  of  erosion  becomes  more  active,  and 
gorges  are  more  and  more  hollowed  out  in  the  thickness  of  the  chain. 
During  the  lapse  of  centuries,  the  differences  in  vertical  outline  between 
the  escarpments  of  the  two  chains  become  very  distinctly  prominent.  In 
the  Pyrenees,  this  relation  of  summits  and  passes  in  two  different  moun- 
tain ridges  can  only  be  pointed  out  in  a  few  instances,  on  account  of  the 
general  simplicity  of  the  chain  and  the  comparative  height  of  the  passes. 
Nevertheless,  here  and  there  we  find  some  unquestionable  examples  of 
this  law ;  thus  the  entrance  of  Venasque  opens  exactly  in  front  of  the 
Maladetta,  and  the  deep  depression  of  the  pass  of  Puy  Moren  is  opposite 
to  the  summits  of  the  Fontargente  group. 

Looked  at  in  an  entirely  general  point  of  view,  this  "law  of  debouch- 
ments" is  nothing  more  than  a  particular  instance  of  the  law  formerly 
pointed  out  by  Buffon  as  to  the  serpentine  form  which  is  presented  by  all 
normal  valleys.  The  salient  angle  of  a  chain  corresponds  to  a  hollow  in 
the  re-entering  angle  of  the  opposite  chain,  the  summit  rises  opposite  to  a 
depression,  and  groups  of  very  elevated  peaks  tally  with  some  pass  more 
depressed  than  any  of  the  others.  Now,  if  the  curves  of  a  valley  render 
it  very  probable  that  an  indentation  of  the  ridge  answers  to  the  convex 
portion  of  the  stream,  we  may  assert  almost  to  a  certainty  that  the  line  of 


SUMMITS  AKD  PASSES.  137 

junction  uniting  two  sharp  bends  of  streams  which  are  separated  by  a 
chain  of  mountains  will  pass  through  a  deep  depij^sion  of  the  ridge. 

The  comparative  studies  which  have  been  mad^y  various  geogrtphers, 
since  Humboldt,  as  to  the  vertical  outline  of  mountain  chains,  have  been 
directed  not  only  to  the  comparative  height  of  passes  and  summits,  but 
also  to  the  mean  inclination  of  mountain  sides.  The  real  slope  of  a  moun- 
tain ridge  is,  as  is  well  known,  the  tortuous  and  variously  inclined  line 
which  is  followed  by  a  streamlet  of  water  in  its  descent  from  the  ridge  to 
the  plain  below;  but  it  is  not  this  more  or  less  regular  curve  which  is 
constituted  the  actual  side  of  the  chain.  It  is,  in  fact,  an  ideal  line  pass- 
ing through  the  secondaiy  summits,  and  over  the  passes  and  dales,  and 
connecting  the  summits  of  the  principal  ridge  with  the  base  of  the  incip- 
ient acclivities  in  the  adjacent  plains.  This  ideal  line  is  never  so  much 
inclined  to  the  horizon  as  the  appearance  of  the  slopes  and  the  sudden 
contrast  between  the  heights  and  the  valleys  would  lead  one  to  expect ; 
painters,  too,  seem  very  naturally  to  exaggerate  by  one  third,  or  even  by 
half,  the  real  relief  of  a  mountain  outline,  so  as  to  give  the  effect  which 
they  truly  enough  produce  on  the  eye  of  the  spectator.  On  the  French 
side,  the  Jura — ^the  general  incline  of  which  is,  however,  very  gentle — 
from  the  crest  of  Mont  Tendre  to  the  town  of  Arbois,  presents  a  total  de- 
clivity of  only  4288  feet — that  is,  a  gradient  of  about  2'6  in  100,  which  is 
but  a  moderate  slope  oven  for  a  coach  road.  The  general  inclination  of 
the  Pyrenees  is  much  more  rapid,  since,  from  the  summit  of  Mont  Perdu 
to  the  plain  of  Tarbes — a  distance  of  thirty-six  miles  as  the  crow  flies — 
the  declivity  is  9980  feet,  or  a  gradient  of  5*2  in  100.  But  even  this  is  a 
much  less  rise  than  that  of  some  of  the  high  hills  on  mountain  roads ;  it 
is,  too,  very  inferior  to  that  of  the  railroad  which  winds  in  zigzags  up  the 
sides  of  Mont  Cenis.  The  most  abruptly  inclined  mountain  side  which 
can  be  found  in  Europe  is  that  face  of  the  Alps  which  is  turned  toward 
the  plains  of  Piedmont  and  Lombardy ;  from  the  summit  of  Monte  Rosa 
to  the  district  of  Ivree,  the  mean  slope  exceeds  10  yards  in  100,  which  to 
the  eye  produces  the  effect  of  an  immense  Babel  of  towers  and  pyramids 
placed  one  above  another.  Certain  mountain  'groups  in  the  New  World 
have  still  steeper  sides;  thus  the  Silla  of  Caraccas  turns  toward  the  Ca- 
ribbean Sea  a  real  wall  rising  at  an  angle  of  54°  to  the  horizon ;  this  would 
be  a  cliff  of  an  all  but  inaccessible  character  if  it  were  not  possible  to 
scale  it  by  zigzag  paths  through  the  gorges  and  ravines.  It  must,  how- 
ever, be  understood  that  the  declivity  of  mountain  sides  is  not  exactly  the 
same  in  every  part  of  the  mountain  groups ;  although  very  steep  at  one 
point,  it  may  be  tolerably  slight  at  another,  in  accordance  with  the  varie- 
ties of  heights,  rocks,  and  climates. 

The  mean  declivity  is  difficult  enough  to  ascertain,  on  account  of  the 
great  diversity  of  slope  in  different  places ;  but  the  total  volume  of  a 
chain  of  mountains  is  a  much  more  difficult  thing  still  to  find  out,  even 
approximately.  Humboldt,  taking  as  his  basis  the  scientific  data  (which 
are  still  too  incomplete)  as  to  the  heights  of  plateaux  and  mountains  in 


138  2'ir^  EARTH. 

various  continents,  has  endeavored  to  estimate  the  cubical  mass  of  sev- 
eral great  mountain  ch^s.  According  to  his  calculations,  the  total  mass 
of  the  Pyrenees,  spread  uniformly  over  the  whole  surface  of  France,  would 
only  raise  the  soil  about  10  feet.*  In  like  manner,  if  all  the  materials  of 
the  Alpine  masses  were  equally  distributed  over  the  continent  of  Europe, 
they  would  only  augment  its  height  about  21^  feet.f  It  would  be  very 
useful  to  renew  these  investigations,  so  as  to  arrive  at  results  which  would 
be  more  and  more  exact,  as  the  orographical  outline  becomes  better  known. 
The  most  perfect  calculation  of  this  kind  which  has  ever  been  made  is 
probably  that  of  Sonklar  as  to  a  portion  of  the  Tyrolese  Alps  known  un- 
der the  name  of  the  Oetzthal  group.  This  mass  would  be  represented  by 
a  solid  body  having  a  uniform  height  of  8333  feet,  of  which  5314  feet 
would  be  for  the  plateau  or  pedestal  of  the  mountainous  region,  and  3019 
feet  would  be  for  the  whole  of  the  peaks.J  This  mass,  if  spread  over  the 
whole  of  Europe,  would  only  represent  an  increase  of  two  feet  in  the 
height  of  the  continent.  We  thus  perceive  that  as  regards  the  question 
of  bulk,  mountain  chains  are  much  less  important  than  plateaux  like  Spain 
or  Bavaria. 

*  In  Otte's  translation  of  Humboldt's  Cosmos,  vol.  i.,  p.  305,  it  is  given  as  115  feet. — Ed. 
t  Cosmos,  Faye's  translation,  vol.  L,  p.  353. 
X  Sonklar,  (Etzthaler  Gehirgsgruppe. 


LAW  OF  MO UNTAIN  CHAINS.  ^39 


CHAPTER  XXm. 

hypotheses  as  to  the  general  laws  of  mountain  chains. — m.  elie  de 
Beaumont's  theoey  of  parallel  upheavals. — chain  of  the  pybe- 

NEES  taken  as  A  TYPE  OF  THE  CORDILLERAS  OR  LONGITUDINAL  CHAIN. 
VARIOUS  IRREGULARITIES  IN  THE  CHAIN. — THE  PYRENEES  AS  AN  ETH- 
NOLOGICAL  BARRIER. 

Several  geographers  have  fancied  that  they  had  discovered  the  law 
of  the  general  aiTangement  of  mountains,  and,  without  so  much  as  wait- 
ing until  the  whole  surface  of  the  earth  became  thoroughly  known,  have 
traced  out,  according  to  their  own  notions,  ranges  of  mountains  more  or 
less  hypothetical.  Thus  Buache,  whose  ideas  were  very  prevalent  for  a 
long  time,  imagined  that  the  chain  of  the  Pyrenees  was  prolonged  under- 
neath the  Atlantic,  then  across  the  New  World  and  the  Pacific,  and,  again 
making  its  appearance  in  Asia,  forming  in  succession  the  Himalaya,  the 
Caucasus,  the  Balkhans,  the  Alps,  and  the  Cevennes,  finally  returned  to 
the  point  it  started  from.  It  was,  in  fact,  the  ancient  image  of  the  myth- 
ical serpent  coiling  itself  round  the  globe  and  biting  its  own  tail.  We 
only  need  to  glance  at  the  maps  which,  at  the  present  day,  science  enables 
us  to  trace  out,  in  order  to  see  how  completely  primitive  this  idea  was  as 
regards  the  harmony  of  the  terrestrial  configuration.  It  is,  on  the  con- 
trary, by  a  singular  variety  of  phenomena  that  the  laws  of  nature  are  al- 
ways revealed. 

Of  course  it  may  be  said,  in  a  very  general  way,  that  the  principal 
chains  of  mountains,  interrupted  here  and  there  by  gulfs,  arms  of  the  sea, 
or  plains,  form  a  kind  of  great  circular  cornice  round  the  double  basin  of 
the  Indian  Ocean  and  the  Pacific*  In  like  manner,  it  is  certain  that  the 
mean  altitude  of  the  elevations  of  the  ground,  both  mountains  and  pla- 
teaux, gradually  diminishes  as  we  leave  the  tropical  regions  and  approach 
the  poles.  But  how  numerous  are  the  exceptions  which  come  under  our 
notice  when  we  study  the  endless  variety  of  the  geographical  lineaments 
of  the  earth's  surface !  Some  countries  seem  a  perfect  labyrinth  of  plains, 
plateaux,  and  mountains,  of  every  shape,  form,  and  height.  In  one  place 
we  find  granite  peaks  and  domes  of  porphyry ;  in  another,  ridges  of  schist, 
cut  up  into  needle-like  points ;  limestone  ramparts  and  basaltic  cones  of 
almost  mathematical  regularity  of  outline.  The  fact  is  this,  that  the  se- 
ries of  mountains  which  have  been  elevated  during  each  period  of  the 
earth's  existence  have  been  added  to  by  successive  series  of  subsequent 
upheavals.  Whatever  the  first  rule  may  have  been,  it  has  gone  through 
an  incessant  process  of  modification  during  the  lapse  of  ages. 

*  Vide  above,  p.  52. 


140  2^.^^  EARTH. 

It  becomes,  therefore,  the  function  of  geology  to  decide  as  to  the  real 
order  of  arrangement  of  mountains  by  describing  the  history  of  their 
formation.  M,  Elie  de  Beaumont  has  endeavored  to  fulfill  this  great  task, 
and,  by  a  bold  generalization  of  scientific  facts,  has  succeeded  in  drawing 
up  a  theory  of  great  simplicity.  Taking  as  his  starting-point  the  fact  that 
the  steeply-inclined  sedimentary  strata  which  stretch  along  the  side  of  a 
mountain  must  necessai-ily  have  been  upheaved,  while  the  strata  which 
have  remained  horizontal  have  not  been  disturbed  since  their  formation, 
the  eminent  geologist  has  thus  been  enabled  to  assign  a  relative  age  to 
each  system  of  mountain  chains.  In  fact,  every  chain  which  presents  on 
its  slopes  the  vertical  beds  of  any  geological  formation,  and  at  the  base  of 
which  we  find  the  strata  of  a  later  age,  must  evidently  have  been  upheaved 
from  the  surface  during  the  longer  or  shorter  interval  which  separated  the 
formations  of  the  two  series  of  strata.  Now,  if  we  compare  the  direc- 
tions of  mountain  systems  of  the  same  age,  we  find  that  they  are  nearly 
parallel  in  the  set  of  their  ridges.  M.  Elie  de  Beaumont  has  therefore 
classified  various  mountain  chains  according  to  their  direction,  and  has  in 
this  way  pointed  out  some  very  remarkable  coincidences  between  ridges 
of  upheaval  separated  from  each  other  by  thousands  of  miles.  One  most 
important  fact  which  results  from  this  classification  of  mountains  is,  that 
the  most  ancient  systems  are  generally  the  least  elevated.  The  Vosges 
date  from  a  much  more  remote  epoch  than  the  Pyrenean  chain ;  the  lat- 
ter was  uplifted  before  the  Alps,  which  also  belong  to  an  age  much  ante- 
rior to  that  of  the  Andes. 

Nevertheless,  this  geological  classification  of  mountains  is  not  so  simple 
as  it  appears  at  first  sight ;  for  it  is  often  very  difiicult  to  determine  the 
real  axis  of  upheaval  of  mountain  chains — a  fact  which  M.  Elie  de  Beau- 
mont found  an  opportunity  of  convincing  himself  of  in  studying  the  sys- 
tem of  the  Esterel.  A  profound  study  of  the  earth's  strata  will  correct  all 
the  false  and  incomplete  elements  which  these  theoretical  ideas  must  con- 
tain. Geography,  which  confines  itself  to  a  description  of  the  earth  as  it 
is  in  the  present  epoch,  can  only  class  the  various  chains  of  mountains  ac- 
cording to  the  regularity  of  their  shape,  their  vertical  outline,  and  the  im- 
portance which  they  assume  in  continents  as  the  divisions  of  the  water- 
shed, as  the  laboratories  of  meteoric  agencies,  and  as  a  barrier  between 
nations. 

Among  the  mountain  chains  which  assume  an  almost  perfect  regulari- 
ty, we  may  mention  the  western  portion  of  the  Pyrenees.  Just  like  a 
branch  of  a  tree,  or  better  still,  a  stalk  of  fern,  is  divided  and  subdivided 
right  and  left  into  small  branches,  leaves,  and  leaflets,  so  every  knot  in  the 
ridge  gives  rise  on  both  sides  to  transverse  chains,  similar  in  every  respect 
to  the  mother-chain,  except  that  they  are  much  shorter,  and  sink  by  succes- 
sive falls  down  to  the  level  of  the  adjacent  plains.  The  transverse  chains 
are  also  parallel,  and  separated  from  each  other  by  deep  valleys,  down 
which  glaciers  rush,  torrents  roar,  or  footpaths  wind.     The  valleys  on 


CHAIN  OF  THE  PYRENEES. 


141 


each  side  of  the  principal  chain  correspond  closely  and  communicate  with 
each  other  by  a  col,porty  or  passage,  that  is,  a  depression  opening  between 
two  summits.  Like  the  principal  ridge,  each  subsidiary  transverse  chain 
is  also  composed  of  a  succession  of  summits,  separated  from  each  other  by 
passes,  the  height  of  which  proportionately  diminishes.  Each  summit  giyes 
rise  to  two  lateral  spurs,  which  are,  in  fact,  nothing  but  the  rudiment  of  a 
tertiary  chain  running  parallel  to  the  principal  one ;  the  secondary  passes, 
too,  serve  to  connect  short  ravines  which  empty  their  streams  into  the 
torrent  of  the  principal  valley. 


Fig.  36.  The  Pyrenees. 

The  portion  oi  the  great  Pyrenean  chain  which  is  comprised  between 
the  pass  of  Roncevaux  on  the  west,  and  the  port  of  Venasque  on  the  east, 
may  therefore  be  considered  as  the  perfect  type  of  a  regular  ridge  of 
mountains.  The  eastern  portion  of  the  chain  is  not  arranged  in  so  order- 
ly a  way:  an  examination  of  the  lines^the  ridge  will  prove  that  at  sev- 
eral points  it  departs  from  the  typicalTinn. 

The  principal  irregularity  is  to  be  found  at  about  the  centre  of  the 
chain,  at  an  almost  equal  distance  from  both  seas.  We  may  there  notice 
that  the  Pyrenean  chain  is  not  of  a  simple  configuration ;  but  that,  on  the 
contrary,  it  is  formed  of  two  distinct  lines,  one  of  which  is  a  continuation 
of  the  regular  western  chain ;  while  the  other,  divided  into  three  parts  by 
the  Col  de  la  Perche  and  the  Col  de  Puymoren,  commences  on  the  shores 
of  the  Mediterranean,  under  the  name  of  the  chain  of  the  Alb^res;  at  the 
Costabona  group  it  crosses  the  more  important  transverse  ridge  of  the 
mountains  of  Cadiz  and  Canigou,  and,  tending  toward  the  east,  forms  the 
clumps  of  Andorre,  Montcalm,  and  Mont  Vallier ;  then  running  parallel  to 
the  chain  coming  from  the  Atlantic,  it  terminates  on  the  right  bank  of 
the  newly-born  Garonne.  The  Pyrenees  may  be  compared  to  a  regular 
chain  which  has  been  divided  into  two  by  some  gigantic  fault,  the  two 
halves  of  which,  remaining  fixed  at  each  of  their  sea-coast  extremities, 
have  turned  slightly  and  in  contrary  directions  round  these  extremities, 
as  if  on  pivots. 


142 


THE  EARTH. 


Fig.  37.  Lateral  Eidge  between  the  Valley  of  Luchon  and  the  Val  d'Aran ;  after  V.  Petit. 


A  transverse  ridge,  abutting  at  right  angles  to  the  northern  chain,  joins 
that  of  the  south  to  the  Col  de  Pallas ;  another,  likewise  thrown  out  at 
right  angles  from  the  range  of  peaks  in  the  southern  chain,  tends  more  to 
the  west,  and  is  only  separated  from  the  Mediterranean  ridge  by  the  nar- 
row defile  of  the  Garonne.  Thus  the  extremities  of  the  two  chains,  and 
the  two  lesser  chains  which  unite  them,  inclose  on  all  sides  a  deep  valley, 
resembling  a  terrestrial  whirlpool,  round  which  the  mountains  rise  like 
enormous  waves.  This  is  the  district  of  Aran,  the  centre  of  the  Pyrenees. 
Although  its  rainfall  flows,  by  i^ans  of  the  Garonne,  into  the  plains  of 
France,  orographically  speakingwP belongs  to  neither  of  the  two  basins. 
With  a  greater  show  of  reason  than  the  valley  of  Andorre,  the  district  of 
Aran  might  have  remained  as  a  neutral  republic  between  France  and 
Spain,  the  two  adjacent  states. 

A  second  anomaly  may  be  found  in  the  fact  that  the  highest  summits 
are  not  situated  on  the  principal  ridge.  Thus  Mont  Perdu,  the  Posets 
Peak,  and  the  Maladetta  rise  to  the  south  of  the  Atlantic  chain  of  the  Pyr- 
enees :  the  first  of  these  mountains  is  connected  with  the  central  axis  by 
several  elevated  passes,  but  the  peaks  of  the  Posets  and  the  Maladetta, 
giants  whichfront  each  other  on  each  side  of  the  Essera,  form  two  almost 
completely  isolated  groups.  On  the  north  side  only,  some  snow-clad  ridges 
link  them  on  to  the  principal  system. 

Nevertheless,  in  spite  of  all  these  irregularities,  resulting  from  the  in- 
cessant labor  of  the«agents  which  are  at  work  in  modifying  the  surface  of 
the  globe,  the  chain  of  the  Pyrenees  must  ever  be  considered  as  an  in- 
stance of  a  regular  system  of  mountains,  and,  among  all  the  ranges  on 
the  face  of  the  earth,  but  very  few  can  even  be  compared  with  it  in  the 
regular  simplicity  of  its  formation.     The  aspect  of  the  Pyrenees  is  there- 


THE  PYRENEES. 


143 


fore  less  diversified  than  that  of  the  Alps  and  of  several  other  mountain 
systems.  The  long  range  bounds  the  horizon  with  a  unifoim  wall,  in- 
dented with  points  like  the  edge  of  a  saw  {sierra)^  and,  looked  at  from 
the  plain,  its  subsidiary  spurs  are  scarcely  visible.  Although  the  mean 
height  of  the  central  ridge  of  the  Pyrenees  exceeds  that  of  the  Alps  by 
about  300  feet,*  and  the  plains  of  France  are  lower  than  those  of  Switzer- 
land, yet  this  superior  comparative  elevation  produces  less  effect  on  the 
spectator  on  account  of  the  rfegular  arrangement  of  the  peaks  and  the  sim- 
ilarity of  their  outlines.  Few,  if  any,  summits  in  the  Pyrenees  exceed  by 
more  than  2000  or  2500  feet  the  mean  height  of  the  ridge  (8037  feet), 
while  in  the  Alps  many  of  the  mountains  rise  more  than  6600  and  8250 
feet  above  the  mean  height  of  the  range,  and  Mont  Blanc  rears  its  termi- 
nal point  to  an  elevation  of  more  than  15,V00  feet.  The  mountains  of  the 
Pyrenees  more  generally  assume  the  form  of  mere  cones  rising  from  the 
upheaved  base.  Some  mountains,  too,  of  considerable  geological  impor- 
tance— as  Neouvielle,  and  the  mountains  of  Oo  and  Clarabide — are  scarce- 
ly to  be  distinguished  by  their  vertical  outline  from  the  heights  which 
surround  them.  Peaks  which  are  plainly  disconnected  from  the  rest  of 
the  chain — such  as  the  Canigou,  Mont  Vallier,  the  Pic  de  Tabe,  the  Pic  du 
Midi  at  Pan,  and  the  Maladetta — are  not  very  numerous. 

In  consequence  of  the  simplicity  of  configuration  which  prevails  in  the 


^.'V^^        Port  de  iutreaZiu 


Fig.  3a  The  Sierra  de  Marcadan,  viewed  from  the  Pic  do  Midi  from  the  Northeast ;  after  V.  Petit. 

Pyrenean  chain,  we  find  in  these  mountains  but  few  of  those  longitudinal 
valleys  rising  up  to  the  right  and  left  toward  two  parallel  ranges  of  peaks, 
and  pushing  their  arms  of  verdure  into  all  the  gorges  and  even  to  the  mo- 
raines of  the  glaciers.  In  these  mountains  we  see  nothing  but  valleys 
which  cross  the  axis  of  the  ridge,  and  are  steeply  inclined  down  toward 
the  plain.  The  passes  where  the  incipient  ravines  of  these  valleys  take 
their  rise  are  often  mere  plateaux  on  the  summit  of  the  ridge,  or  else  dark 
gorges  hollowed  out  in  the  rock  by  the  long-protracted  labor  of  various 
atmospheric  agencies.  These  passes  are  also  more  elevated  on  the  aver- 
age than  those  of  the  Central  Alps.  It  is  therefore  easy  to  understand 
why  it  is  that,  among  all  the  natural  ramparts  in  Europe,  the  Central  Pyr- 
enees have  always  been  the  most  insurmountable  barrier  of  nations.  Be- 
tween the  Col  de  la  Perche,  near  Montlouis,  and  the  port  of  Maya,  no* 'far 
from  Bayonne,  a  distance  of  more  than  180  miles,  the  chain  of  the  Pyre- 
nees is  not  crossed  by  any  carriage-road. 

•  Hamboldt 


144  ^^^  EARTH. 


CHAPTER  XXIV. 

MOUNTAINS  OF  CENTRAL  EUROPE. — CONTRAST  BETWEEN  THE  ALPS  AND  THE 
JURA. THE  JURA  AS  A  TYPE  OP  A  SYSTEM  OF  MOUNTAINS  WITH  PARAL- 
LEL CHAINS. APPARENT  CHAOS  OF  THE  ALPS. CENTRAL  GROUP  OF  ST. 

GOTHARD. — GROUPS  OP  MONTE  ROSA  AND  MONT  BLANC. — THE  ALPS  CON- 
SIDERED AS  A  FRONTIER. 

The  great  system  of  mountains  which  forms,  as  it  were,  the  back-bone 
of  Europe,  and  the  ramifications  of  which,  like  the  limbs  of  a  body,  deter- 
mine the  very  shape  of  the  continent  itself,  is  very  different  from  the  Pyr- 
enees in  the  richness  and  variety  of  its  configuration,  the  intersection  of 
its  ridges,  the  number  of  its  more  isolated  groups,  and  its  frame-work  of 
secondary  chains.  To  the  vertical  outline  and  distribution  of  the  Alps — 
the  glaciers  of  which  supply,  while  they  moderate,  the  water-courses  of 
Western  Europe — the  nations  which  inhabit  the  latter  country  owe  indi- 
rectly much  of  their  vitality  and  civilization.  Standing  up  like  the  bas- 
tions of  a  fortification,  the  chief  Alpine  groups  form  a  protection  to  the 
brave  Swiss  people.  On  the  south,  the  ensemble  of  all  the  mountain  groups 
sweeps  in  a  vast  semicircle  round  Northern  Italy,  and  is  linked  on  tp  the 
chain  of  the  Apennines,  which  constitute  the  back-bone  of  the  peninsula ; 
on  the  west,  the  spurs  of  the  Alps  form  the  most  prominent  feature  of  the 
French  territory,  and  by  their  transverse  chains  modify  the  relief  of  the 
Jura ;  on  the  north,  the  gradation  of  plateaux,  which  abut  on  the  moun- 
tains of  Switzerland,  descend  as  far  as  the  landes  of  Prussia ;  finally,  to  the 
east,  the  Carnic  Alps  extend  into  Bosnia  and  Servia  in  calcareous  ranges 
and  plateaux,  which  are  divided  only  by  the  Danube  from  the  Transylva- 
nian  citadel  of  the  Carpathians,  and,  through  the  Balkhans  and  the  Pindus 
Mountains,  radiate  out  to  the  shores  of  the  Black  Sea  and  the  ^gean. 

The  singular  beauty  of  the  Alps  is  still  further  enhanced  by  the  contrast 
which  they  present  to  the  mountains  which  surround  them.  The  contrast 
is  especially  remarkable  between  the  groups  of  the  Central  Alps  and  the 
ramparts  of  the  Jura  which  form  the  western  boundary  of  the  natural 
territory  of  Switzerland.  The  chains  of  the  Jura,  more  unpretending  in 
height  in  comparison  with  those  of  the  Alps,  are  nevertheless  very  curious 
in  a  geological  point  of  view,  and  must  be  looked  upon  as  the  best  type 
of  one  particular  formation  of  mountains — that  of  long  parallel  ridges. 
Carniola,  Herzogovina,  and  Bosnia  also  possess  chains  arranged  in  a  simi- 
lar manner.  In  America,  too,  we  might  point  out  the  Ozark  Mountains, 
and  especially  the  Alleghanies,  which  extend  over  a  still  more  considera- 
ble area  than  the  Jura,  but  they  have  been  much  less  studied.  They  are, 
besides,  connected  on  both  sides  with  granitic  mountains ;  and  the  princi- 


THE  JURA  AND  THE  ALPS. 


145 


pal  mass  of  the  system,  which  is  often  compared  to  long  waves  of  the  sea, 
is  complicated  with  numerous  irregularities. 


Fiff.  i'.K  'i'he  Jura. 


The  European  Jura  occupies  a  very  considerable  area  in  the  middle  of 
the  continent,  from  the  banks  of  the  Drome  to  the  mountains  of  Bohemia. 
The  central  portion  of  this  immense  tract  of  land  is  all  that  is  commonly 
understood  under  the  name  of  Jura;  for  the  more  extreme  points  are  very 
variously  inflected  and  intersected  by  masses  of  distinct  formations.  Thus, 
in  Savoy,  the  Mole  and  other  peaks  stand  at  the  angles  where  the  walls 
of  the  Jura  intersect  the  Alpine  chains.  The  Jura,  properly  so  called,  ex- 
tends from  the  southwest  to  the  northeast,  from  the  valley  of  the  Rhone 
to  that  of  the  Rhine,  presenting  a  slight  convexity  toward  France.  It 
consists  of  parallel  and  almost  uniform  ranges,  which  rise  in  successive 
gradations,  tending  from  the  west  to  the  east.  These  ranges  are  like  so 
many  walls,  with  sloping  declivities  on  one  side,  and  terminating  on  the 
other  in  abrupt  escarpments.     Intermediate  valleys  separate  these  paral- 

K 


j^46  ^^^'  EABTH. 

lei  walls,  the  most  eastward  of  which  is  by  far  the  most  elevated,  and  com- 
mands, in  all  its  height,  the  plains  of  Switzerland.  Hollows  or  combes, 
in  the  form  of  an  amphitheatre,  open  out  in  the  thickness  of  the  Jura  ram- 
parts, and  here  and  there  duses,  or  transverse  defiles,  enlivened  by  tor- 
rents, cut  right  through  the  chains  and  divide  them  into  isolated  frag- 
ments. These  fragmentary  plateaux,  which,  in  their  extensions,  follow 
uniformly  the  same  direction,  have  been  often  compared  to  those  species 
of  caterpillars  which  creep  along  the  ground  in  long  processions.  If  we 
take  no  notice  of  the  cluses  which  divide  the  walls  of  the  Jura  into  so 
many  bits,  we  may  more  poetically  compare  these  mountains  to  the  rip- 
ples produced  by  throwing  a  stone  upon  some  liquid  surface. 

The  elongated  brows  of  Mont  Tendre,  of  Mont  Noir,  and  the  Weissen- 
steiri  form  magnificent  observatories,  from  which  one  can  study  at  ease 
the  marked  contrast  between  the  Jura  and  the  groups  of  the  Oberland, 
bristling  with  its  pointed  summits,  to  the  east  of  the  Bernese  depression. 
At  first  sight,  these  mountains  seem  to  form  a  veritable  chaos ;  but  this 
chaos  appears  much  greater  still  when  seen  from  one  of  the  lofty  summits 
of  the  Alps  themselves.  We  then  perceive,  round  the  whole  line  of  the 
horizon,  points,  pinnacles,  and  ridges,  thrown  together  as  if  by  chance,  and 
almost  innumerable ;  they  might  well  be  called  the  congealed  waves  of 
an  immense  ocean.  Very  different  from  the  Jura,  the  general  formation 
of  which  is  so  striking  in  its  regularity,  the  Alps  appear  to  be  nothing  but 
a  dreadful  accumulation  of  disorder,  and  only  a  long  course  of  study  or 
personal  survey  will  enable  any  one  to  become  acquainted  with  the  gen- 
eral arrangement  of  their  ridges.  It  may  then  be  seen  that  the  ensemble 
of  these  mountains  is  formed  by  separate  groups  throwing  out  branches 
in  every  direction,  like  the  rays  of  a  star.  Whilst  the  Jura,  and  the  sys- 
tems of  mountains  belonging  to  the  same  type,  are  composed  of  parallel 
chains,  the  Alps  are  constituted  by  the  juxtaposition  of  many  groups  with 
divergent  chains  radiating  from  them. 

M.  Desor,  taking  as  the  basis  of  his  classification  of  the  Alps  the  various 
nuclei  of  granite  and  protogene  which  have  pierced  through  the  more  re- 
cent rocks,  has  come  to  the  conclusion  that  the  Alpine  system  is  composed 
of  fifty  distinct  groups.  This  entirely  geological  division  harmonizes  in 
general  with  the  results  of  a  mere  study  of  the  vertical  outline  and  direc- 
tion of  the  ridges ;  but  the  number  of  groups  must  be  considerably  re- 
duced if  those  which  are  linked  to  one  another  by  continuous  ridges  of 
great  elevation  are  looked  upon  as  forming  parts  of  the  same  chain. 

The  central  mass,  which  is  also  the  most  important  in  a  geographical 
point  of  view,  is  that  of  the  St.  Gothard,  situated  between  Switzerland  and 
Italy,  at  the  summit-level  of  the  waters  of  the  Rhine,  the  Tessin,  the 
Rhone,  the  Aar,  and  the  Reuss ;  it  is  the  knot  or  focus  where  the  conver- 
gent ridges  of  the  surrounding  groups  unite  like  radii.  On  the  northeast 
stands  the  group  of  Todi;  on  the  east,  that  of  Rheinwald;  on  the  west 
and  south,  the  much  more  considerable  clusters  of  the  Finsteraarhorn  and 
Monte  Rosa.     The  latter  group  is  linked  on  to  Mont  Blanc,  rising  more  to 


TM£  JURA  A2sD  TEE  ALPS. 


147 


40.  Valleys,  Cliises,  and  Corabes  of  the  Jura. 


the  west ;  but  at  this  point  the  Alpine  system  changes  its  direction,  and, 
as  a  whole,  bends  round  toward  the  south.  The  two  first  of  the  more  im- 
portant groups  which  rise  on  this  side  are  those  of  the  Grand  Paradis, 
commanding  the  plains  of  Piedmont,  and  that  of  the  Vanoise  and  Grande 
Casse,  dividing  the  Tarentese  and  Maurian  valleys.  A  real  chain  bends 
round  to  the  south,  which  is  crossed  by  the  Mont  Cenis  road ;  the  wind- 
ing ridges  of  these  chains  go  on  to  join  the  groups  of  the  Grandes  Rous- 
888  and  Belledonne  on  the  west,  that  of  the  Grand  Pelvoux  on  the  south- 
west, and  that  of  Monte  Viso  toward  the  south.  Tlie  pyramid  of  Monte 
Viso  is  the  magnificent  boundary-stone  which  marks  out  the  line  of  de- 
markation  between  the  Alps  of  Dauphiny  and  the  Maritime  Alps;  it  is 
also  the  last  mountain  in  the  chain  the  height  of  which  exceeds  11,500 
feet.  Beyond  this  point,  the  terminal  branches  of  France  and  Italy,  spread 
out  like  the  leaves  of  a  fan,  gradually  sink  down  towarc^  the  sea.  To  the 
north  of  Nice  andMentone,  a  small  granite  group  rises  to  a  height  of  more 


148  THE  EARTH. 

than  9900  feet,  and  two  of  its  highest  summits,  the  Gelas  and  the  Clapier 
de  Pagarin,  have  small  glaciers  on  their  northern  slopes.  At  this  point 
the  great  curve  of  the  Western  Alps  comes  to  a  termination,  and  the  in- 
termediate chain  commences  which  unites  the  former  to  the  ridge  of  the 
Apennines. 

The  Eastern  Alps,  situated  to  the  east  of  the  St.  Gothard,  also  assume  a 
similar  arrangement  in  groups.  On  the  northeast  of  the  Todi  stands  the 
Santis ;  to  the  east  of  the  Rheinwald  are  the  groups  of  the  Bernina,  Sil- 
vretta,  and  the  Ortelspitze ;  then  follow,  tending  from  west  to  east,  the 
groups  of  the  Oetzthal,  the  Stubaier,  the  Gross-Glockner,  and  the  moun- 
tains of  Hallstadt,  beyond  which  the  Alps  proper  lose  their  primary  im- 
portance. The  summits  of  all  these  groups  are  more  than  9900  feet  in 
height,  and  are  clad  with  snow ;  like  the  western  chains,  they  well  de- 
serve the  name  of  Alps  (white)  which  the  Celts  gave  to  these  mountains. 

Most  of  these  Alpine  groups  exhibit  a  singular  diversity  of  aspect,  in 
all  the  various  details  of  their  relief  There  is  no  feature  in  this  mighty 
architecture  which  is  devoid  of  its  own  special  characteristics  of  beauty, 
and  also  there  is  no  beauty  which  is  not,  by  some  unlooked-for  contrast, 
individualized  in  each  mountain. 

In  the  first  place,  the  central  group  of  the  St.  Gothard,  the  knot  from 
which  radiate  all  the  principal  chains,  is  not  very  lofty,  and  is,  in  fact,  of 
an  altogether  secondary  class  in  comparison  with  the  other  Alpine  groups. 
It  is  a  quadrilateral  mass,  surrounded  on  all  sides  by  deep  valleys  and  the 
wide  depressions  of  several  passes — on  the  west  the  Furka,  on  the  north 
the  Oberalp,  on  the  east  the  Lukmanier,  on  the  south  the  Nufenen,  and  is 
crowned  by  summits,  the  mean  height  of  which  attains  9678  feet ;  the  most 
important,  the  Piz  Rotondo,  not  exceeding  10,488  feet  in  altitude.  It  is 
probable  that,  during  the  long  course  of  ages,  the  upper  waters  of  the 
Rhine,  the  Rhone,  the  Reuss,  the  Tessin,  and  the  Toccia  have  had  the  ef- 
fect of  lowering  the  mountains  of  St.  Gothard  somewhat  below  the  sur- 
rounding summits. 

Another  anomaly  in  the  Alpine  system  is  the  fact  that  the  mean  eleva- 
tion of  the  snowy  groups  which  rise  east  and  west  of  the  St.  Gothard  is 
not  in  direct  proportion  to  the  heights  of  their  crowning  summits.  In  fact, 
the  true  citadel  of  the  Alps — that  which,  by  the  form  of  its  mountains,  the 
number  of  its  peaks,  and  the  importance  of  its  glaciers,  deserves  more  than 
any  other  the  title  of  the  culminating  group — is  the  mighty  bastioned 
rampart  of  Monte  Rosa,  the  mean  height  of  which  is  not  less  than  13,457 
feet.  The  supreme  diadem  of  this  association  of  mountains  is  at  a  height 
of  15,216  feet,  while  Mont  Blanc  rises  to  15,780  feet;  but  the  group  of 
summits  which  surround  this  highest  point  of  Europe  is  only  12,657  feet 
in  mean  altitude,  800  feet  less  than  the  heights  of  Monte  Rosa.  Next  fol- 
low in  order  of  elevation  the  groups  of  the  Jungfrau,  12,312  feet;  the  Ber- 
nina, 11,345  feet;  the  Grison  Alps,  10,583  feet,  and  the  Todi,  10,311  feet. 
Taken  as  a  whole,  the  various  groups  of  the  central  Alps  decrease  in  height 
from  west  to  east,  and  from  south  to  north ;  their  southern  slope  is  uni- 


Dravm  'by  A  Vuilleiivin. 


HARP  HP    6-  iP.'vXh'E 


ALPS 


PL.  X. 


£n^^  bjr    £rhsrd 


K?!'/r-Y.;sii., 


UTRUCTURE  OF  THE  ALPS. 


149 


formly  more  abrupt  than  the  northern  declivities,  which  descend  in  long 
branches  toward  the  valleys  of  the  Rhone  and  the  Rhine.* 

Considered  in  their  ensemble^  the  Alps,  like  most  mountains,  serve  as 
chains,  ethnological  frontiers,  on  one  side  to  the  French  and  Germans,  and 
on  the  other  to  the  inhabitants  of  Italy.  The  district  of  the  Grisons,  one 
of  the  most  inaccessible  of  all  the  Alpine  regions,  which  by  the  labyrinth 
of  its  five  hundred  valleys  has  been  converted  into  the  central  citadel  of 
Europe,  served  as  a  refuge  to  the  Rhetian  peoples,  who  still  speak,  though 
in  a  corrupted  form,  the  language  of  their  ancestors — the  contemporaries 
of  the  citizens  of  ancient  Rome.  The  Alps,  however,  owing  to  their  di- 
visions into  numerous  groups  and  to  the  comparative  lowness  of  their 
passes,  do  not  constitute  an  insuraiountable  barrier  like  the  chain  of  the 
Pyrenees.  On  the  mountains  and  in  the  valleys  of  Switzerland,  men  be- 
longing to  three  races — German,  French,  and  Italian — are  confederated  so 


'^'V-.yv 


ioci 


4  miles. 


Fig.  41.  Profile  of  Monte  Rosa. 

as  to  form  a  nation  of  brethren.  German  colonies,  surrounded  on  all  sides 
by  a  Latin  population,  have  established  themselves  on  the  mountain  sides 
facing  the  north ;  for  instance,  in  the  Viege  valley  and  in  the  Sette  Com- 
muni  in  the  environs  of  Bassano.  Added  to  this,  men  of*  the  Latin  race 
have  colonized  the  southern  slopes  of  the  groups  inhabited  principally  by 
Germans;  finally,  the  ancient  AUohroges,  all  alike  nowadays  speaking 
more  or  less  impure  French,  inhabit  the  two  sides  of  the  Alps  of  Savoy 
and  Dauphiny,  While,  in  the  Pyrenees,  the  ridge  of  the  mountains  dis- 
tinctly separates  the  two  nations  of  France  and  Spain,  it  is,  on  the  con- 
trary, the  bases  of  the  Piedmontese  mountains  which  serve  as  frontiers,  if 
not  political,  at  least  ethnographical,  between  two  races.  The  valleys  of 
the  Italian  side,  traversed  by  the  streams  of  the  two  Doires,  the  Cluson, 
the  Pellis,  and  the  Stura,  have  a  population  of  the  same  stock  as  the  val- 
leys of  Maurienne,  Queyras,  and  Dur9,nce.  Besides,  as  Ami  Boue,  the  ge- 
ologist, long  ago  pointed  out,  longitudinal  chains  are  those  which  form 
the  least  separation  between  peoples,  owing  to  the  resemblance  of  the  cli- 
♦  William  lluber,  Bulletin  de  la  Society  de  Geographie,  February,  March,  18G6. 


150  T^^  EARTH. 

mate  on  the  two  slopes;  transversal  chains,  like  the  Pyrenees,  are  always 
the  frontiers  which  are  the  most  difficult  to  cross. 

For  all  the  interchanges  of  commerce,  as  well  as  for  the  mutual  inter- 
course of  peoples,  the  Alpine  groups  are  also  much  more  happily  arranged 
than  the  regular  chain  of  the  Pyrenees;  and  the  traffic  between  the  two 
opposite  sides  has  always  assumed  a  very  considerable  importance.  Twelve 
carriage  roads,  some  of  which  may  be  reckoned  among  the  chefs  cPceuvre 
of  human  industry,  cross  the  ridges  of  the  Alps,  and  form  the  means  of 
communication  between  France,  Switzerland,  and  Germany;  a  railway 
also,  now  some  years  finished,  passes  to  the  east  of  the  Greater  Alps 
through  the  Soemmering  chain.  Finally,  four  other  railway  lines  are 
gradually  pushing  their  way  into  the  depths  of  the  lofty  central  moun- 
tains, and,  ere  long,  free  communication  will  be  established  under  the 
rocks  and  glaciers,  and  we  shall  be  able  to  make  the  boast  that  we  have 
leveled  the  Alps. 


MOUNTAINS  OF  CENTRAL  ASIA.  151 


CHAPTER  XXV. 

MOUNTAIN  CHAINS  OP  CENTRAL  ASIA. — THK  KOUEN-LUN,  THE  KARAKORTTM, 
THE  HIMALAYA, — THE  SOUTH  AMERICAN  ANDES,  A  TYPE  OF  THE  BIFUR- 
CATED  CHAIN. 

The  chains  of  the  Himalaya,  the  Karakorura,  and  the  Kouen-Lun  fill 
the  same  position  in  the  continent  of  Asia  as  that  occupied  by  the  Alps  in 
Europe.  These  three  ranges  of  mountains  have  a  common  origin  in  the 
plateau  of  Pamir — the  "  Roof  of  the  World" — from  which  also  radiate  to- 
ward the  north  and  west  the  ranges  of  the  Bolor  and  the  Hindoo-Kuch. 
The  triple  rampart  of  Upper  Asia  is  not  less  than  1550  miles  in  linear  de- 
velopment, and  its  breadth,  including  that  of  the  plateaux  and  intermedi- 
ate valleys,  is  toward  the  east,  that  is,  toward  Sikkim,  about  620  miles. 
Jn  each  of  the  three  chains  the  mean  altitude  of  the  summits  exceeds  that 
of  any  other  ridge  of  mountains  in  the  rest  of  the  world ;  this  spot  is,  in 
fact,  the  culminating  point  of  the  earth.  Between  the  two  extreme  sides 
the  contrast  is  most  decided.  On  the  north,  cold  and  arid  steppes  stretch 
away  over  an  immense  extent;  on  the  south  lie  spread  out  the  burning 
and  wonderfully  fertile  plains  which  are  watered  by  the  Ganges  and  its 
tributaries.  The  rocky  and  snowy  ridges  which  tower  up  between  the 
two  regions  form  an  ethnological  barrier  more  mighty  than  the  ocean  it- 
self; they  divide  races  of  men  and  great  systems  of  religion.  There  are 
but  very  few  points  at  which  the  Buddhist  Mogols — thanks  to  'the  great- 
er facilities  which  were  afforded  them,  by  their  residence  on  the  high 
plateaux,  for  crossing  the  mountains — have  made  their  way  down  into  the 
Southern  valleys  of  the  Himalaya.* 

The  northern  chain,  that  of  the  Kouen-Lun,  is  very  little  known,  and  it 
can  not  as  yet  be  stated  positively  whether  it  may  not  contain  some  sum- 
mits more  elevated  even  than  those  of  the  Himalaya.  It  is,  however, 
probable,  from  the  information,  that  has  been  acquired  by  travelers  as  to 
various  points,  that  the  ridge  of  the  Kouen-Lun  is  the  least  lofty  of  the 
three.  The  Karakorum,  which  is  the  middle  rampart,  is  also  that  of 
which  the  mean  height  is  the  most  considerable;  and  in  its  gorges  the 
Indus  and  the  Brahmapootra  take  their  rise.  At  its  base  lies  Ij^ie  valley 
of  Cashmere,  which  the  Oriental  posts  celebrate  as  the  "abode  of  happi- 
ness ;"  its  lovely  blue  lakes,  surrounded  with  gardens,  reflect  the  snowy 
peaks  of  fifteen  or  eighteen  thousand  feet  in  height.  The  torrents  which 
flow  from  both  sides  of  the  mountains  cross  the  parallel  chains  through 
prodigious  defiles,  which  in  some  places  reach  a  depth  of  thousands  of 
feet. 

*  Frferes  Sohlagintweit,  Mittheilungen  von  Petermann. 


152 


THE  EARTH. 


Fig.  42.  Valley  of  Cashmere. 


The  Himalaya,  the  best  known  of  the  three  chains,  has,  however,  been 
but  slightly  explored  in  comparison  with  the  European  Alps.  It  is  pro- 
tected against  all  the  attempts  of  explorers  by  the  want  of  roads  and  eve» 
paths;  by  its  impetuously-rushing  streams,  entirely  unbridged;  by  the 
inaccessible  forests  of  its  slopes ;  by  its  formidable  cliffs,  and  the  height 
of  its  lofty  summits,  piercing  through  the  clouds  into  the  attenuated  air, 
where  man  can  scarcely  draw  his  breath.  On  the  face  of  the  mountains 
a  zone  of  variable  width  extends,  like  a  barrier  of  death.  This  is  the  Te- 
rai,  the  unwholesome  dampness  of  which,  fostered  by  the  rains  of  the  mon- 
soons and  the  water  descending  from  the  Himalaya,  steams  in  the  sun  in 
long-drawn  out  mists,  creeping  over  the  trees,  and  spreads,  far  and  wide, 
fevers  and  pestilence.  Finally,  several  of  the  mountain  districts  still  be- 
long to  native  sovereigns,  who  oppose,  either  by  force  or  stratagem,  any 
advance  of  European  travelers.  It  is  not  many  years  ago  that  observers 
were  first  able  to  measure  the  highest  mountain  in  the  chain,  and  proba- 
bly in  the  whole  world.  This  is  the  Gaurisankar,  or  Tchingo-Pamari,  the 
summit  of  which  rises  to  a  height  of  29,002  feet,  nearly  twice  the  eleva- 
tion of  Mont  Blanc.     In  the  same  range,  uji  to  the  present  time,  two  hun- 


THE  EIMALA  YAS.—THE  AJWES.  153 

dred  and  sixteen  summits  have  been  measured,  seventeen  of  which  exceed 
24,600  feet  in  altitude ;  forty  are  about  23,000  feet,  and  a  hundred  and 
twenty  more  than  20,000  feet  high.  Next  to  the  Gaurisankar,  the  high- 
est known  mountain  is  the  Dapsang  (28,29f  feet),  in  the  Karakorum. 

The  great  peaks  of  the  Himalaya,  contemplated  from  one  of  the  head- 
lands which  stand  out  far  into  the  plains  of  Hindostan,  form  one  of  the 
most  magnificent  spectacles  which  the  eye  of  man  can  see  and  wonder  at. 
From  the  village  of  Durjeling,  which  the  English  have  built  upon  a  ter- 
race more  than  6000  feet  above  the  level  of  the  sea,  in  order  to  enjoy  a 
cold  and  bracing  air  like  that  of  their  native  countiy,  may  be  seen  rising, 
in  all  its  formidable  majesty,  the  colossus  of  Kinchinjinga,  nearly  five  miles 
high.  At  its  base,  as  if  in  the  bed  of  a  gulf  of  verdure,  a  white  torrent 
of  foam  glitters  through  the  palm-trees ;  higher  up,  a  chaos  of  wooded 
mountains,  like  the  waves  of  a  monstrous  sea,  are  crowded  and  piled  one 
over  the  other  round  the  great  tranquil  summit ;  above  the  multitude  of 
secondary  peaks  rise  the  long  slopes  of  the  mountain,  fii*st  tinged  with  an 
aerial  blue  softer  than  that  of  the  sky,  then  with  a  bright  white,  sparkling 
like  silver.  From  one  snowy  ridge  to  another,  the  eye  rises  at  last  to  the 
culminating  point,  from  which  the  bold  climber,  if  he  ever  reaches  it,  might 
see  stretched  out  at  his  feet  a  prospect  as  extensive  as  that  of  the  whole 
of  France.* 

Spectacles  as  grand  as  that  of  the  Kinchinjinga,  seen  from  Durjeling, 
are  numerous  enough  in  the  Himalaya,  especially  in  the  eastern  portion 
of  the  chain,  where  the  summits  attain  their  principal  elevation,  and  where 
the  defiles  of  the  valleys  are  most  deeply  hollowed  out.  But,  although 
these  mighty  mountains  of  Upper  Asia  are  more  majestic  than  the  Euro- 
pean Alps,  they  do  not  generally  present  an  equal  variety  of  aspect,  an 
equal  grace  of  outline,  or  charm  of  landscape.  In  all  its  grandeur,  the 
Himalaya  is  uniform ;  its  peaks  are  loftier,  its  snows  more  extensive,  its 
forests  deeper ;  but  there  are  fewer  cascades  and  lakes ;  there  are  no  pleas- 
ant lawns  and  scattered  groves;  and  we  fail  to  notice  the  picturesque 
chdlets  nestling  down  in  the  glens  or  hanging  over  the  brink  of  the  preci- 
pices. 

The  South  American  Andes,  which  in  1824 — that  is,  before  the  discov- 
eries of  Webb  and  Moorcroft — were  looked  upon  as  superior  in  elevation 
to  the  Himalaya,  are,  in  fact,  6600  feet  lower  in  mean  height.  In  sublim- 
ity they  are  exceeded  by  the  Asiatic  mountains,  in  variety  of  site  by  the 
European  Alps ;  but  they  are  distinguished,  especially  in  the  volcanic  re- 
gions, by  regularity  of  form.  Added  to  this,  they  constitute  a  chain  which, 
in  a  geographical  point  of  view,  is  really  unique,  on  account  of  the  har- 
mony which  they  exhibit  with  the  continent  which  they  crown  with  their 
snowy  ridges.  This  long  range  of  mountains,  so  remarkable  by  its  enor- 
mous length  (about  4350  miles),  and  by  the  great  height  which  its  peaks 
maintain,  over  a  space  of  about  50  degrees  of  longitude,  is,  however,  less 
regular  than  it  appeal's  at  first  sight.  The  principal  characteristic  which 
*  Hooker,  Himalayan  Journal. 


154  'PS^^  EARTH, 

distinguishes  the  Andes  from  every  other  mountain  system  is  found  in 
the  numerous  forks,  or  rather  bipartitions,  of  the  Cordillera.  In  that  part 
only  of  their  extent  which  stretches  from  the  frontiers  of  Chili  to  those 
of  Venezuela,  the  Andes  divide  eight  times,  forming  large  inclosures,  each 
containing  a  plateau  between  the  two  lines  of  peaks.  At  some  points,  in- 
deed, the  Andes  separate  in  three  scarcely  divergent  branches. 

From  the  southern  point  of  America,  as  far  as  the  other  side  of  Acon- 
cagua (22,420  feet) — the  giant  of  the  Chilian  Andes — the  principal  chain 
throws  out  to  the  east  but  very  unimportant  groups.  There  are  only 
some  low  ridges  running  above  the  Pampas  parallel  to  the  principal  ridge. 
About  the  30th  degree  of  latitude  these  uplands  augment  in  number  and 
height,  and  then  form  a  vast  plateau,  from  which,  in  a  northeasterly  direc- 
tion, branches  off  the  great  sierra  of  Aconquija.  Other  sierras  rise  on  the 
enormous  mass  of  the  plateau  between  the  mountains  of  Aconquija  and 
the  great  fork  of  the  Bolivian  Cordillera,  in  the  2 2d  degree  of  latitude. 
The  western  range,  composed  of  broad  domes  of  a  regular  shape,  ap- 
proaches the  shore  of  the  Pacific,  while  the  eastern  chain,  throwing  out 
several  important  branches  into  the  eastern  plains,  curves  round  the  great 
plateau  of  Bolivia,  with  its  long  row  of  serrated  and  snowy  peaks,  among 
which  towers  the  Illampu  or  Sorata  (24,812  feet),  the  highest  mountain 
in  America.  North  of  the  lake  of  Titicaca  the  two  chains  are  united  by 
a  transverse  rampart,  but  they  continue  to  extend  in  a  northwest  direc- 
tion parallel  to  the  coast.  Although  the  eastern  Cordillera  is  pierced  in 
a  great  many  points  by  rivers  which  are  tributaries  of  the  Amazon,  it  can 
still  easily  be  recognized  by  the  general  direction  of  the  fragments  which 
compose  it. 

At  the  knot  of  Cerro  de  Pasco  the  two  Cordilleras  again  unite,  but  only 
to  divide  again  immediately  into  three  chains,  one  of  which,  tending  to 
the  northeast,  merges  in  the  Pampa  del  Sacramento,  while  the  two  oth- 
ers, inclosing  between  them  the  deep  valley  of  the  Maraiion,  unite  at  the 
extreme  angle  near  the  southern  frontiers  of  Ecuador.  More  to  the 
north,  we  have  several  small  plateaux  covered  with  virgin  forests ;  then, 
on  the  other  side  of  Loja,  the  two  Cordilleras  again  separate  their  two 
parallel  ridges  of  snow-clad  summits.  Here,  too,  lies  the  magnificent  ter- 
race of  Ecuador,  divided  into  three  distinct  plains  by  the  cross  groups  of 
Assuay  and  Chisincha.  Two  of  these  plains,  those  of  Tapia  and  Quito, 
form  the  magnificent  avenues  of  volcanoes  rendered  celebrated  by  La 
Condamine,  Bouguer,  Humboldt,  and  other  learned  travelers.  On  one  side 
rise  Chimborazo,  Carahuirazo,  Illinissa,  Corazon,  and  Pichincha ;  on  the 
other,  Sangay,  the  most  formidable  volcano  in  the  world,  Tunguragua, 
Cotopaxi,  Antisana,  and  Cayamba,  which  crosses  the  line  of  the  equator.* 

North  of  the  equator,  the  two  chains  unite  in  forming  the  group  of  the 

Pasto  plateau,  which  stretches  nearly  up  to  the  second  degree  of  latitude. 

At  this  spot  commence  three  distinct  Cordilleras,  which  are  not  destined 

again  to  unite  into  another  knot  of  mountains.     The  western  Cordillera 

*  Vide  the  chapter  on  "Volcanoes." 


THE  ANDES.  I55 

disappears  close  to  the  Gulf  of  Darien,  between  the  valleys  of  the  Atrato 
and  Cauca.  The  central  Cordillera,  on  which  rise  the  mighty  summits  of 
Purace,  Huila,  Tolima,  and  Herveo,  divides  the  Cauca  basin  from  that  of 
the  Magdalena ;  lastly,  the  eastern  Cordillera,  or  the  Suma  Paz  (supreme 
peace),  bending  round  to  the  west  of  the  plateau  of  Bogota,  forks  out  into 
two  chains  near  Pamplona,  one  of  which  terminates  in  the  vicinity  of 
Maracaibo,  under  the  name  of  the  Sierra  Negra,  while  the  other,  variously 
ramified,  bounds  on  the  north  the  Uanos  of  Venezuela,  and,  forming  the 
proud  Silla  of  Caraccas,  runs  along  the  sea-coast,  and  pushes  out  as  a 
promontory  to  the  Bouche  du  Dragon,  which  separates  it  from  the  moun- 
tains of  the  island  of  Trinidad.  This  point  forms  the  termination  of  the 
chain  of  the  Andes.  The  immense  and  spirally  inflected  extent  of  the 
Cordillera  has  for  its  culminating  summits  three  peaks — Chimborazo,  So- 
rata,  and  Aconcagua — placed  about  1240  miles  apart  on  the  mighty  ridge ; 
but  the  summits  which  are  higher  than  Mont  Blanc  may  be  reckoned  by 
hundreds.  This  enormous  mountain  chain  seems  to  form  so  intimate  a 
pai-t  of  the  veiy  construction  of  the  continent,  that  numbers  of  the  inhab- 
itants of  its  plateau  and  slopes  look  upon  it  as  the  back-bone  of  the  whole 
world ;  they  can  not  fancy  any  country  which  is  not  commanded  by  the 
Cordillera  of  the  Andes.* 

*  Jules  Remy,  Nouvelles  Annales  des  Voyages,  February,  1865. 


156  ^^^  EARTH. 


CHAPTER  XXVI. 

GRADUAL  COOLING  OP  THE  AIR  ON  MOUNTAIN  SIDES. — DIFFICULTY  OF  AS- 
CENTS. —  LIMITS  OF  man's  HABITATION.  —  ILLNESS  FELT  BY  MOUNTAIN 
TRAVELERS. 

By  uplifting  their  summits  into  the  higher  regions  of  the  atmosphere, 
mountains  penetrate  through  zones  of  ever-increasing  cold,  and,  owing  to 
this  gradation  of  successive  temperatures,  nature  assumes  a  marvelous  va- 
riety of  climates  and  floras.*  The  sides  of  every  lofty  mountain  present 
a  kind  of  epitome  of  all  the  phenomena  which  are  exhibited  in  the  im- 
mense space  comprehended  between  the  plains  at  its  foot  and  the  icy  re- 
gions of  the  pole. 

The  solar  rays  have  actually  more  heating  power  on  the  soil  of  moun- 
tains than  in  the  plains,  as  is  shown  by  direct  observation,  and  also  by  the 
marvelous  colors  of  the  sweet-smelling  Alpine  flowers  ;f  therefore  the 
gradual  cooling  of  the  temperature  on  mountain  slopes  must  be  attributed 
to  the  rarefaction  of  the  successive  layers  of  air.  The  investigations  and 
experiments  of  natural  philosophers  have  proved  that  the  air  affords  a 
much  easier  passage  to  luminous  than  to  dark  radiations.  The  result  of 
this  fact  is  that  the  heat  poured  down  by  the  sun  during  the  daytime 
readily  traverses  the  whole  depth  of  the  atmosphere  in  its  way  to  warm 
the  surface  of  the  planet,  while  the  heat  radiated  from  the  ground  during 
the  night  can  only  escape  into  space  in  very  small  quantities.  The  lower 
layers  of  the  atmosphere  thus  act  as  complete  screens  in  arresting  the  ra- 
diation from  the  surface  of  the  earth,  and  preventing  the  cooling  of  the 
planet.  By  this  very  fact,  however,  slopes  and  summits  of  mountains  are, 
in  proportion  to  their  elevation,  the  more  easily  deprived  of  the  heat  which 
warms  the  plains  at  their  base,  and  they  mount  into  tracts  of  air  which 
are  the  more  chilled  in  proportion  as  they  are  vertically  distant  from  the 
denser  atmospheric  layers  lying  below,  J  Thanks  to  this  progressive  dimi- 
nution of  temperature  in  the  aerial  waves  which  bathe  them,  mountains, 
already  so  beautiful  in  their  outline  and  the  majesty  of  their  forms,  add 
to  the  magnificence  of  their  appearance  by  the  contrast  between  their 
forests  and  their  glaciers,  their  pasture-lands  and  their  snowst 

What,  then,  on  the  average,  is  the  proportion  according  to  which  the 
temperature  falls  in  ascending  from  the  base  to  the  summit  of  a  moun- 
tain ?  It  is  a  difficult  matter  to  settle  it  exactly,  for  aerial  currents  of  va- 
rious temperatures  lie  one  above  the  other  in  the  heights  of  the  atmos- 

*  Vide  the  chapter  on  "  The  Earth  and  its  Flora. " 
t  Ch.  Martins.     Helmholz,  La  Glace  el  les  Glaciers. 
X  Tyndall,  The  Glaciers  of  the  Alps. 


LIMITS  OF  MA2PS  HABITATION.  I57 

pbere,  and  sometimes  we  may  rise  from  a  comparatively  cold  zone  to  one 
that  is  much  warmer,  as  some  of  the  aeronautic  expeditions  of  Mr.  Glaisher 
have  strikingly  proved.  Nevertheless,  when  the  sky  is  clear  and  the  air 
is  calm,  the  decrease  of  the  temperature  takes  plade  with  a  regularity 
which  is  suflSciently  certain  to  enable  us  to  calculate  the  law  respecting 
it,  at  least  approximately.  Just  above  the  sui-face  of  the  ground,  an  ele- 
vation of  143  feet  corresponds,  on  the  average,  to  a  fall  of  one  degree 
Fahrenheit;  at  the  height  of  about  3000  feet,  it  takes  an  increase  of  height 
of  294  feet  to  eftect  a  diminution  of  heat  amounting  to  one  degree  Fahr- 
enheit ;  and  in  proportion  as  we  mount  higher  and  higher,  the  interval  in- 
creases, so  that  at  about  30,000  feet  of  elevation  the  temperature  sinks 
only  one  degree  Fahrenheit  for  every  space  of  1055  feet.*  The  real  rate 
of  the  decrease  of  heat  can  not  be  so  easily  ascertained  on  the  slopes  of 
mountains,  on  account  of  the  influence  of  the  ground  and  the  ice.  But  we 
may  state  generally  that  on  the  Swiss  mountains  the  temperature  of  sum- 
mer decreases  one  degree  Fahrenheit  for  every  vertical  space  of  290  feet ; 
in  winter  the  same  fall  of  temperature  takes  place  for  every  439  feet  of 
increased  height.f 

The  extreme  cold  of  very  lofty  mountains  renders  them  completely  un- 
inhabitable for  man.  No  traveler  has  ever  set  his  foot  on  the  mighty 
summits  of  the  Karakorum  and  the  Himalaya.  The  principal  summits  of 
the  Andes  —  Sorata  and  Aconcagua — are  equally  inviolate;  and  even 
among  the  more  unpretending  summits  of  the  Alps  there  are  still  a  con- 
siderable number  on  which,  up  to  tHe  present  time,  the  snows  and  the  gla- 
ciers have  formed  a  suflScient  barrier  against  any  attempted  ascents.  The 
highest  point  that  the  mountain  climber  has  yet  attained  is  the  summit 
of  Ibi-Gamin,  a  mountain  of  Thibet,  which  rises  22,079  feet  above  the  level 
of  the  sea.  Even  at  this  considerable  height  the  brothers  Schlagintweit, 
who  accomplished  this  exploit  in  1856,  still  found  themselves  more  than 
6500  feet  below  the  culminating  point  of  Gaurisankar.  Since  this  date, 
Mr.  Glaisher's  balloon  has  reached  an  elevation  of  more  than  13,000  feet 
higher  in  the  cold  atmosphere  of  Great  Britain. 

In  all  mountainous  regions  the  permanent  habitations  of  man  cease  at  a 
limit  far  below  the  most  elevated  points  reached  by  the  bold  mountain 
climber.  St.  Veran  and  Gurgl,  the  most  highly-placed  villages  of  France 
and  Germany,  are  situated  at  the  respective  altitudes  of  6591  and  6197 
feet;  but  in  Switzerland  the  Hospice  of  St.  Bernard,  built  many  centuries 
ago  to  shelter  travelers  when  benumbed  with  the  cold,  is  much  more  ele- 
vated— its  height  i8  8110  feet.  There  is  another  convent — that  ofHanle, 
inhabited  by  twenty  Thibetian  priests,  which  is  the  most  elevated  cluster 
of  houses  in  the  whole  world;  it  is  situated  at  a  height  of  14,976  feet.  J 
None  of  the  villages  of  the  Andes,  except  perhaps  that  of  Santa-Anna,  in 
Bolivia,  have  been  built  at  so  great  a  height,§ 

*  Ztircher,  J n/jMaf re  Scicnfi^^w,  1864.  +  Helmholz,  Z>i  Glace  et  les  Glaciers. 

X  Rol)ert  de  Schlagintweit,  A/i'/Mei/Mn^cn  von  Petermann,  1865. 
§  Keck,  Geographisc/ies  Jahrbuk  von  Behm. 


158  THE  EARTH. 

Travelers  who  venture  to  ascend  the  slopes  of  a  lofty  mountain  not 
only  have  to  suffer  all  the  rigors  of  cold  and  run  the  risk  of  being  frozen 
on  their  route,  but  they  may  also  experience  most  painful  sensations,  ow- 
ing to  the  rarefaction  of  the  air.  It  is,  in  fact,  very  natural  that,  at  an 
elevation  at  which  the  pressure  of  the  atmosphere  is  reduced  to  one  half 
or  even  to  one  fourth  that  of  the  plains  below,  a  certain  uneasiness  should 
be  caused  by  the  sudden  change,  and  the  more  so.  that  some  of  the  other 
surrounding  conditions,  such  as  the  caloric  and  the  humidity  of  the  air, 
also  become  modified.  Undaunted  climbers  like  Tyndall,  who  have  never 
felt  in  their  own  persons  the  effect  of  this  mal  de  montagne^  expressly 
deny  that  this  exhaustion  proceeds  from  any  thing  else  than  mere  fatigue. 
M.  Jules  Kemy,  too,  has  noticed  only  one  mountain  of  the  Andes  on  which 
the  phenomena  of  thejowna  or  soroche  are  always  developed  in  the  organ- 
ism of  living  beings ;  this  is  the  Cerro  de  Pasco,  the  height  of  which  does 
not  exceed  13,966  feet.  Horses,  mules,  asses,  and  oxen  are  also,  like  man, 
subject  to  the  peculiar  influence  of  these  localities,  while  at  much  more 
considerable  altitudes  the  usual  state  of  health  suddenly  returns.  There- 
fore, in  this  region  of  the  Andes,  emanations  from  the  ground,  and  not  the 
rarefaction  of  the  air,  are  the  cause  to  which  we  must  attribute  the  incon- 
venience felt  by  travelers.*  However,  the  investigations  made  on  the  sub- 
ject by  Robert  de  Schlagintweitf  cai\  leave  no  doubt  in  our  minds  that 
this  mountain  ailment  is  really  felt  generally,  in  other  regions  of  the  An- 
des as  well  as  on  the  Cerro  de  Pasco.  Usually,  indeed,  the  effects  of  the 
soroche  are  felt  at  a  much  lower  elevation  on  the  slopes  of  the  Cordilleras 
than  on  those  of  the  Himalaya.  In  the  latter  mountains  the  traveler  does 
not  begin  to  suffer  from  the  attacks  of  this  ailment  until  he  has  reached  a 
height  of  16,600  feet,  while  on  the  Andes  a  large  number  of  persons  are 
affected  by  it  at  an  altitude  of  10,700  and  11,500  feet.  Added  to  this,  in 
the  South  American  mountains  the  symptoms  are  much  more  serious ;  to 
the  fatigue,  headache,  and  want  of  breath,  which  ai'e  likewise  experienced 
on  the  Himalaya,  are  added  giddiness,  sometimes  fainting-fits,  and  bleed- 
ing from  lips,  gums,  and  eyelids.  J  At  the  same  elevation  as  the  paramos 
of  the  Andes,  or  even  as  the  lofty  summits  of  the  Himalaya,  the  aronaut 
— who,  however,  is  spared  all  the  fatigue  of  climbing — rarely  suffers  any 
inconvenience ;  but  at  30,000  to  40,000  feet  the  malady  shows  itself,  and, 
if  the  balloon  continued  to  rise,  the  aerial  voyager  would  infallibly  perish. 
Therefore,  at  but  a  very  few  miles  above  our  heads  lies  the  region  of 
death,  and  into  this  terrible  zone  the  loftiest  mountains  of  the  earth  ele- 
vate their  white  summits.  * 

*  Aitrension  du  Pichinchn,  Nouvelles  Annales  des  Voyages,  etc.,  Febniaiy,  ISfiS. 

t  Zeitschr.fiir  Erdkunde,  1866.  %  Humboldt,  Poeppig,  Moritz  Wagner,  Philippi. 


SUBHWENCE  OF  MOUNTAmS.  159 


CHAPTER  XXVn. 

6BADUAL  SUBSIDENCE  OP  MOUNTAINS  DURING  THE  LAPSE  OP  AGES. — SUD- 
DEN DOWNFALLS  AND  CHAOS. — THE  FALL  AT  FELSBEBG. — SLOW  ACTION 
OF   METEORIC   AGENCIES. 

The  formidable  mountain  citadels  which  tower  up  so  high  over  the 
habitations  of  man,  along  the  sides  of  which  creep  clouds  and  thunder, 
do  not,  however,  escape  a  slow  but  certain  process  of  sinking  so  soon  as 
the  upheaving  force  which  pushed  them  out  of  the  earth  has  ceased  to 
act.  Assisted  by  the  force  of  gravity  which  is  constantly  tending  to  level 
the  surface  of  the  ground,  meteoric  agents  are  unceasingly  persistent  in 
the  destruction  of  mountains.  They  open  valleys  and  gorges,  they  hol- 
low out  passes,  they  undermine  their  summits,  either  by  sudden  down- 
falls, or,  more  generally,  by  a  slow  and  continuous  erosion.  Sooner  or 
later,  the  Andes  and  the  Himalaya,  those  mighty  continental  ridges,  will 
become  mere  ranges  of  hills,  like  many  another  ancient  mountain  chain, 
which,  too,  once  formed  the  back-bone  of  a  world. 

Great  mountain  downfalls,  although  of  no  very  great  importance  in  a 
geological  point  of  view,  are  among  the  most  tremendous  phenomena  of 
planetary  vitality :  whenever  such  a  catastrophe  has  occurred,  tradition 
has  handed  down  the  recollections  of  it  for  long  centuries.  No  event  is 
calculated  to  produce  a  more  forcible  effect  in  the  popular  mind.  Per- 
pendicular or  overhanging  rocks,  which  seem  to  hang  suspended  over  the 
plains,  suddenly  become  detached  and  rush  headlong  down  the  mountain 
side ;  in  their  rapid  fall  they  raise  a  cloud  of  dust  like  the  ashes  vomited 
forth  by  a  volcano ;  a  horrible  darkness  is  spread  over  the  once  pleasant 
valley ;  and  the  cataclysm  is  known  only  by  the  trembling  of  tlie  ground 
and  the  crushing  din  of  the  rocks  striking  together  and  shattering  one  an- 
other in  pieces.  When  the  cloud  of  dust  is  cleared  away,  nothing  but 
heaps  of  stones  and  rubbish  are  to  be  seen  where  pastures  and  cultivated 
land  once  were ;  the  stream  flowing  down  the  valley  is  obstructed  in  its 
course  and  changed  into  a  muddy  lake ;  the  rampart  of  rocks  has  lost  its 
old  form,  and  on  its  sides,  from  which  some  debris  are  still  crumbling 
down,  the  sharpened  edges  point  out  the  denuded  cliff  from  which  a  whole 
quarter  of  the  mountain  has  broken  away.  In  the  Pyrenees,  Alps,  and 
other  important  chains,  there  are  but  few  valleys  where  we  may  not  no- 
tice these  chaos-like  heaps  of  fallen  rocks. 

The  principal  catastrophes  of  this  kind  which  have  taken  place  in  the 
mountains  of  Europe  during  the  present  era  are  facts  which  are  well 
known.  Southward  of  Plaisance,  in  Italy,  the  ancient  Roman  town  of 
Velleja  was  buried  about  the  fourth  century  by  the  downfall  of  the  only 
too-well-named  mountain  of  Rovinazzo,  and  the  large  quantity  of  bones 
and  coins  that  have  been  found  proves  that  the  subsidence  of  the  rocks 
was  so  sudden  that  it  did  not  even  afford  the  inhabitants  any  chance  of 


160  THE  EARTH. 

escape.  Tauretunum,  another  Roman  town,  situated,  it  is  said,  on  the 
banks  of  the  Lake  of  Geneva,  at  the  base  of  one  of  the  spurs  of  the  Dent 
d'Oche,  was  completely  crushed  in  A.D.  563  by  a  downfall  of  rocks ;  the 
declivity  that  it  formed  may  still  be  seen  advancing  like  a  headland  into 
the  waters  of  the  lake,  which  at  this  spot  is  not  less  than  520  feet  deep. 
A  terrible  flood-wave,  produced  by  the  deluge  of  stones,  invaded  the  op- 
posite shoi'es  of  the  lake,  and  swept  away  all  the  habitations — fromMorges 
to  Vevay  every  town  and  every  village  on  the  banks  was  demolished ; 
and  they  did  not  commence  to  rebuild  them  until  the  following  century. 
Geneva  itself  was  in  part  covered  by  the  water,  and  the  bridge  over  the 
Rhone  was  swept  away.  According  to  MM.  Troyon  and  Morlot,  howev- 
er, these  disasters  were  caused  by  a  landslip  which  fell  from  the  Gram- 
mont  or  Derochiaz  across  the  valley  of  the  Rhone,  just  above  the  spot 
where  it  flows  into  the  Lake  of  Geneva.  The  effect  of  this  was  the  for- 
mation of  a  temporary  lake,  and  the  shores  were  devastated  by  an  inun- 
dation at  the  time  of  the  destruction  of  the  natural  barriers  by  the  accu- 
mulated water.* 

The  great  downfalls  of  rocks  which  have  taken  place  during  historical 
periods,  in  the  Alps  and  neighboring  mountains,  may,  in  fact,  be  reckoned 
by  hundreds.  In  1248,  four  villages  situated  at  the  base  of  Mont  Granier, 
not  far  from  Chambery,  were  buried  under  a  mass  of  calcareous  rubbish, 
which  the  water-courses  have  now  ravined  out  and  moulded  into  little 
hillocks ;  small  pools,  known  by  the  name  of  abimes,  are  dotted  about 
amongst  these  heaps  of  debris,  which  are  nowadays  covered  with  cultiva- 
tion. In  1618  the  downfall  of  Monte  *Conto  buried  the  2400  inhabitants 
of  the  village  of  Plurs,  near  Chiavenna.  Two  out  of  the  five  peaks  of  the 
Diablerets  fell  down,  one  in  1714,  and  the  other  in  1749,  covering  the  pas- 
tures with  a  layer  of  debris  more  than  300  feet  thick,  and,  obstructing  the 
course  of  the  stream  of  Lizerne,  formed  the  three  lakes  of  Derborence 
which  are  now  existing.  In  like  manner,  the  Bernina,  the  Dent  du  Midi, 
the  i)ent  de  Mayen,  and  the  Righi  have  overspread  with  their  fragments 
vast  tracts  of  cultivated  land ;  but  no  catastrophe  of  this  kind  has  left 
more  fearful  reminiscences  of  horror  thart  the  fall  of  a  section  of  the  Ross- 
berg  on  the  2d  of  September,  1806.  This  mountain,  situated  to  the  north 
of  the  Righi,  in  the  centre  of  the  peninsula-like  space  formed  by  the  lakes 
of  Zug,  Egeri,  and  Lowerz,  consists  of  a  compact  conglomerate,  lying  on 
beds  of  clay,  which  hinder  the  infiltration  of  the  surface  water.  At  some 
unknown  epoch  the  falling  rubbish  of  a  mountain  spur  destroyed  the  vil- 
lage of  Rotten ;  but  in  1 806  the  catastrophe  was  still  more  terrible.  The 
season  which  had  just  tenninated  had  been  very  rainy,  and  the  clay  strata 
had  gradually  changed  into  a  muddy  mass ;  at  last,  the  rocks  above,  los- 
ing their  supporting  basis,  began  to  slip  down  the  mountain  side,  plowing 
up  the  ground  in  front  of  them  like  the  bow  of  a  ship  pushes  up  the  water 
before  it.  Suddenly  a  general  break  up  took  place.  In  a  moment,  an 
enormous  mass,  carrying  with  it  forests,  meadows,  hamlets,  and  inhabit- 
ants, rushed  down  into  the  plain.  Flames,  produced  by  the  friction  of 
«     *  Bulletin  de  la  Society  Vaitdoise. 


FALL  OF  MOUNTAIN  JilASSES. 


161 


the  rocks  striking  and  rubbing  against  one  another,  broke  in  fiery  jets 
from  the  half-opened  mountain.  The  water  deposited  in  the  deep  beds, 
suddenly  converted  into  steam,  burst  out  with  explosive  force,  and  show- 
ers of  mud  and  stones  were  vomited  out  as  from  the  mouth  of  a  volcano. 
The  charming  plains  of  Goldau  (the  Vallee  d'Or),  and  four  villages,  inhab- 
ited by  nearly  a  thousand  persons,  disappeared  under  the  heaps  o^  debris  ; 
the  Lake  of  Lowerz  was  partly  filled  up ;  and  the  furious  wave  which  the 
falling  mass  drove  up  on  to  the  banks  swept  away  all  the  houses  on  it. 
The  catastrophe  occurred  in  so  sudden  a  way  that  the  very  birds  were 
killed  as  they  were  flying  in  the  air.  The  portion  of  the  mountain  which 
slipped  down  was  not  less  than  two  miles  and  a  half  long,  by  about  350 
yards  wide  and  35  yards  thick ;  it  was  a  mass  containing  more  than  fifty- 
four  millions  of  cubic  yards.* 


Fig.  43.  Great  Landslip  of  Goldaa. 


Whatever  may  be  the  geological  importance  of  these  fearful  mountain 
downfalls,  still  they  are  but  phenomena  of  a  secondary  class  in  compari- 
son with  the  results  produced  by  the  slow  and  gradual  action  of  various 
atmospheric  agencies — frost,  air,  and  rains.  These  are  the  incessant  and 
indefatigable  workers  which,  by  their  continual  labor,  have  enlarged  the 
first  clefts  open  here  and  there  in  the  thickness  of  rocks,  and  ha\TB  hollow- 
ed out  all  the  net-work  of  passes,  amphitheatres,  combes^  defiles,  cliises, 
glens,  and  valleys,  the  endless  ramifications  of  which  add  so  much  variety 
to  the  mountain  structure.  Owing  to  these  operations,  continued  with- 
out intermission  during  the  long  centuries  of  geological  periods,  the  lofti- 
est summits  are  being  gradually  lowered,  and  the  materials  deiived  from 
their  slopes  are  spread  far  and  wide  over  the  plains,  or  borne  down  to  the 
waters  of  the  ocean. 

*  Henri  Zschokke.     Otto  Volger,  Erdbeben  der  Schweiz. 
L 


PAKT  III. 
THE  CIRCULATION  OF  WATER. 


CHAPTER  XXVIII. 

SNOW-PALL   ON  MOUNTAINS. — LOWER   LIMIT   OF   SNOW. — ZONE    OF  PERPET- 
UAL  OR   PERMANENT  SNOW. 

There  are  few  sights  more  charming  than  that  of  the  clouds  sweeping 
in  long  trains  over  the  sides  of  a  mountain,  and  leaving  behind  them  on 
the  slopes  a  covering  of  fresh-fallen  snow.  We  may  often  notice  that  the 
lower  portion  of  a  cloud  breaks  up  into  showers,  and  inundates  with  rain 
the  less  elevated  slopes,  while  higher  up  the  colder  vapors  are  discharged 
in  flakes  of  snow.  A  line,  which  is  sometimes  uncertain,  but  is  usually 
pretty  definitely  traced  across  the  declivity  of  the  mountain,  marks  out 
the  limit  of  temperature  above  which  the  clouds  fall  in  snow,  and  runs 
with  remarkable  regularity  above  the  verdant  tracts  which  have  been 
watered  by  the  rain. 

This  lower  snow-limit  is  traced  round  the  mountain  side  at  different 
elevations,  according  to  the  seasons.  In  winter  it  gradually  descends  to 
the  base  of  the  Alps  and  Pyrenees ;  in  spring  and  summer  it  rises  little 
by  little  toward  the  summits,  and  even  mounts  above  them  when  they 
do  not  reach  any  very  great  elevation.  For  the  most  part,  however,  the 
higher  mountain  chains  have  their  ridges  always  covered  with  snow,  and 
a  line  may  be  drawn  across  their  declivities,  changing  more  or  less  in  va- 
rious centuries  and  years,  above  which  the  snow  never  entirely  melts. 
This  is  the  so-called  snow-line,  or  limit  of  the  perpetual  snow ;  it  Avould  be 
better  described  as  the  limit  oi permanent  snow. 

Above  the  lower  snow-line  the  snow  is  constantly  being  partially  melt- 
ed and  then  again  renewed ;  thus  the  bed  of  snow-flakes  becomes  gradu- 
ally thicker  and  more  heaped  up,  owing  to  the  fall  of  the  temperature  in 
these  high  regions.  More  snow,  in  fact,  falls  than  the  rays  of  the  sun  and 
the  heat  of  the  earth  can  dissolve  in  one  warm  season ;  enormous  masses, 
therefore,  fill  up  all  the  gorges  and  ravines,  and  drifts  of  several  yards  in 
depth  cover  those  rocks  and  cliffs  which  are  not  too  steep  to  allow  the 
snow  to  accumulate  on  their  slopes.  All  lofty  mountains  are,  therefore, 
clad  with  veils  of  snow ;  but  it  is  certain  that  if  they  rose  to  a  still  more 
considerable  elevation  into  the  regions  of  air,  they  would  ultimately,  and 
indeed  before  long,  reach  a  limit-line  above  the  very  snow  itself    In  fact, 


SNOWFALL  ON  MOUNTAINS.  Ig3 

the  cold  regions  of  the  higher  atmosphere  contain  only  a  very  small  pro- 
jiortion  of  misty  vapor;  and  the  scanty  flakes  of  snow  which  would  fall 
on  summits  45,000  to  60,000  feet  high  (if  any  such  existed)  would  be  soon 
swept  away  by  the  wind  or  melted  by  the  solar  rays.  On  the  sides  of  a 
mountain  of  this  elevation  there  would  be  a  belt  of  permanent  snow, 
bounded  on  the  lower  side  by  a  region  of  pasture-ground,  and  on  the 
upper  by  tracts  of  desert  perfectly  devoid  of  vegetation.*  According  to 
Tschudi,  the  quantity  of  snow  which  falls  on  that  portion  of  the  Alps 
which  is  above  a  height  of  about  10,800  feet  is  comparatively  very  small. 
Most  of  the  clouds  charged  with  snow-flakes  discharge  their  burden  on 
the  mountain  slopes  at  elevations  of  7600  to  8600  feet.  At  these  heights 
moisture  falls  sometimes  also  in  the  form  of  rain;  but  at  10,000  feet  the 
clouds  but  rarely  assume  the  shape  of  showers,  and  at  12,000  feet  they 
bring  nothing  but  snow.  Observations  made  in  the  Alps  prove,  however, 
that  the  quantity  of  snow  falling  on  different  mountains  varies  singularly, 
according  to  the  altitude  and  the  aspect  of  the  slopes;  and  in  each  par- 
ticular locality^  according  to  the  climatic  circumstances  of  the  year.  At 
the  Hospice  of  Grimsel,  situated  at  a  height  of  6148  feet,  M.  Agassiz  no- 
ticed a  fall  of  snow  in  six  months  of  winter  amounting  to  57^  feet — equiv- 
alent to  five  feet  of  water.  Some  years  afterward,  in  the  same  place,  W. 
Huber,  the  engineer,  ascertained  that  the  thickness  of  the  bed  of  snow 
was  59  feet  during  a  period  of  double  this  duration.  On  the  St.  Bernard, 
at  8110  feet  of  altitude,  the  thickness  of  snow  has  varied  during  twelve 
years  (from  1847  to  1858)  from  11^  feet  to  44:|:  every  year.  This  would 
give  a  difference  of  one  and  four  in  a  yearly  snow-fall  on  the  same  point 
of  the  mountain.!  It  appears  that  on  the  St.  Gothard,  at  an  elevation  of 
6867  feet  above  the  level  of  the  sea,  the  annual  deposit  of  snow  is  more 
considerable  than  on  the  St.  Bernard ;  for  in  one  night's  time  the  thick- 
ness of  the  fallen  snow  was  sometimes  increased  as  much  as  %^  feet.  J  The 
snow  which  falls  on  the  mountain  summits  is  but  seldom  composed  of 
those  elegant  shapes,  the  marvelous  configuration  of  which  we  so  much 
admire  in  the  valleys.  It  usually  consists  of  small  granules  as  fine  as 
dust,  slender  needles  of  ice,  and  stars  with  almost  imperceptible  rays ;  it 
is,  in  fact,  sleet,  and  not  snow,  properly  so  called.  It  often  happens  that 
the  slightest  change  in  the  direction  of  the  atmospheric  currents  substi- 
tutes a  fall  of  granular  snow  for  one  composed  of  flakes,  or  produces  the 
reverse  phenomenon.  We  can  not,  however,  as  Agassiz  has  pointed  out, 
establish  any  well-defined  distinction  between  the  two  different  kinds  of 
sleety  or  flaky  snow. 

It  is  very  difficult,  or,  indeed,  impossible,  to  fix  the  altitude  above  which 
beds  of  snow  may  always  be  perceived  on  various  groups  of  mountains. 
This  limit  varies  according  to  the  aspect  and  inclination  of  the  slopes, 
the  nature  and  color  of  the  rocks,  the  force  and  average  direction  of  the 
winds,  the  quantity  of  the  snow  which  fills,  and  all  the  meteorological 

♦  Humboldt.  Tyndall.  f  Bibliotheque  de  Geneve. 

J  Eugene  Flaclmt,  La  Traversie  des  Alpes. 


IQ4:  THE  EARTH. 

phenomena  of  the  region  into  which  the  summits  rise.  It  is,  therefore, 
only  approximately,  and  entirely  in  a  general  way,  that  we  can  venture 
to  point  out  the  height  of  this  unsettled  line,  fluctuating,  as  it  does,  from 
year  to  year,  and  from  century  to  century,  under  the  combined  influence 
of  solar  heat  and  atmospheric  agencies.  According  to  the  brothers 
Schlagintweit,  the  so-called  limit  of  perpetual  snow  in  the  central  Alps 
would  fluctuate  between  9000  and  9240  feet  of  altitude;  and  for  the 
group  of  Mont  Blanc,  between  9400  and  10,200  feet.  Nevertheless,  it  is 
very  certain  that  in  September,  1842,  a  neighboring  mountain  to  the 
Jungfrau — the  Ewigschneehorn,  the  German  name  of  which  signifies  peak 
of  eternal  snows — showed  nothing  but  the  bare  ground  on  all  its  slopes.* 
In  like  manner,  in  1860  and  in  1862  the  summits  of  the  Alps  presented 
only  partial  stains  of  white  snow,  and  tourists  could  cross  the  Strahlech 
(10,993  feet)  without  walking  for  a  single  instant  on  any  snow,  either 
fresh  or  hardened.f  In  1855  Sonklar  could  not  perceive  a  trace  of  snow 
on  the  Hangerer,  a  mountain  in  the  Austrian  Alps,  which  rises  to  a  height 
of  9994  feet. J  Similarly,  in  the  autumn  of  1859,  the  summit  of  the  Cha- 
berton  (10,295  feet),  near  Mont  Genevre,  was  completely  bare  of  snow. 
With  regard  to  the  Pyrenees,  in  which  the  limit  of  permanent  snow  would 
be  from  9000  to  9240  feet  in  height,  it  is  certain  that  the  Montcalm,  which 
rises  to  an  elevation  of  10,101  feet,  is  topped  by  a  kind  of  plateau  which 
is  often  perfectly  clear  of  snow  during  the  hot  season,  and  even  dotted 
over  with  bunches  of  grass.  On  the  Spanish  side  of  the  Pyrenees,  toward 
the  middle  of  August,  nothing  but  the  bare  rock  is  to  be  seen,  except  in 
the  deep  hollows  which  the  south  wind  can  not  penetrate.  The  ideal 
snowy  zone  with  which  geographers  clothe  the  lofty  Pyrenean  peaks  has, 
in  fact,  no  absolutely  permanent  existence. 

The  same  thing  may  be  likewise  affirmed  of  a  large  number  of  mount- 
ain chains  that  we  are  accustomed  to  class  with  those  which  are  crowned 
by  perpetual  snow.  The  ideal  line,  therefore,  which  is  traced  in  most 
atlases  as  fixing  the  limits  of  the  snowy  zone  on  the  outline  of  mountains 
can  only  be  considered  as  having  an  approximate  value.  According  to 
Durocher,  the  line  of  perpetual  snow,  which  passes  at  a  height  of  13,731 
feet  over  the  sides  of  the  equatorial  Andes,  would  be  only  705  feet  lower 
than  on  the  great  mountains  of  Mexico — Popocatepetl  and  Orizaba. 
There  is  another  phenomenon  which  is  much  more  surprising  still :  in  the 
southern  hemisphere,  south  of  the  Peruvian  Andes,  this  snow-line  ceases 
to  sink,  and  even  rises  to  more  than  16,500  feet  of  altitude.  On  the  pla- 
teaux of  the  Chilian  and  Argentine  Andes,  between  22  and  33  degrees  of 
south  latitude,  where  the  temperature  naturally  falls  much  lower  than  in 
the  corresponding  regions  of  Ecuador,  the  mean  limit  of  snow  is  actually 
higher ;  which,  nq  doubt,  is  owing  to  the  great  dryness  of  the  winds. 
Thus  travelers  have  seen  the  slopes  of  the  Cordillera  of  Mendoza  on  the 

*  Desor,  Nouvelles  Excursions. 

+  Dollfuss-Aussett,  Mat^riaux  pour  V Etude  des  Glaciers,  vol.  v. 

}  (Etzthaler  Gebirgsgruppe, 


LIMIT  OF  PERMANENT  SNOW. 


165 


22d  degree  of  latitude  swept  perfectly  clear  of  snow  up  to  the  height  of 
13,200  feet ;  at  four  degrees  farther  north  no  white  surface  is  seen  to 
glitter  on  the  Sierra  Famatina  (14,764  feet).  In  the  Tropic  of  Capricorn, 
the  Sierra  de  Zenta,  the  summits  of  which  rise  16,404  feet  above  the 
level  of  the  sea,  is  but  very  rarely  covered  with  snow  even  during  the 
winter,  and  the  layers  of  flakes  which  are  brought  by  the  clouds  im- 
mediately melt.  Lastly,  according  to  Pentland,  the  western  slopes  of 
the  Bolivian  Andes,  which  are  very  seldom  blown  upon  by  damp  winds, 
exhibit  no  instances  of  perpetual  snow  at  a  less  height  than  18,370  feet. 
In  a  general  way,  any  humidity  that  falls  evaporates  without  giving  rise 
to  the  smallest  rivulet  of  water,  or  even  without  moistening  the  ground. 
Toward  the  middle  of  the  day,  the  clouds  may  be  seen  from  afar  floating 
up  from  the  heights  of  the  mountains  like  smoke,  and  disappearing  at  an 
immense  altitude  in  the  deep  azure ;  these  are  the  snows  of  yesterday  re- 
ascending  into  the  atmosphere  in  the  form  of  vapor.* 

The  astonishing  contrast,  as  regards  the  lower  snow-limit,  between  the 
northern  slopes  and  the  southern  side  of  the  mountain  chains  of  Central 
Asia,  must  be  attributed  to  the  unequal  distribution  of  the  rain-fall.  The 
climate  is  naturally  much  moi-e  rigorous  on  the  north  side  of  the  Hima- 
laya than  in  the  valleys  turned  toward  the  south,  and  yet  in  the  former 


Fig.  44.  Liinii  uf  Permanent  Snow  in  South  America. 


the  snow-covered  tracts  do  not  descend  nearly  so  low.  This  contrast  is 
so  striking  that  every  traveler  has  remarked  it,  and  has  even  exaggerated 
its  importance,  until  the  recent  explorations  of  the  brothers  Schlagintweit. 
According  to  Hooker,  the  botanist,  on  the  southern  sides  of  the  Himalaya 
the  mean  limit  of  perpetual  snow  exceeds  13,943  feet,  and  on  the  opposite 
slope  rises  to  18,589  feet  of  altitude  ;  so  that  precisely  the  coldest  side  is 
denuded  of  snow  at  a  point  4646  feet  higher  than  the  declivities  exposed 
♦  Maitin  de  Moussy,  Con/ediration  Argentine,  vol.  i. 


IQQ  THE  EARTH. 

to  the  burning  sun  of  Hindostan,  The  comparative  observations  of  the 
brothers  Schlagintweit  have  considerably  reduced  this  enormous  differ- 
ence between  the  two  slopes.'  For  the  southern  and  northern  slopes, 
these  travelers  have  ascertained  the  mean  limits  to  be  respectively  16,049 
feet  and  17,237  feet,  which  reduces  the  total  difference  to  1188  feet.  But 
farther  on  in  these  regions  the  contrast  may  be  made  more  considerable, 
for  in  Thibet  many  mountains,  at  an  altitude  of  even  more  than  20,000 
feet,  may  be  seen  denuded  of  every  snowy  particle.  Lately,  in  accordance 
with  Humboldt,  this  great  height  of  the  snow-limit  on  the  northern  slopes 
of  the  Himalaya  was  attributed  to  the  reaction  of  the  solar  rays  after 
falling  on  the  plateaux  of  Central  Asia ;  but  the  brothers  Schlagintweit, 
by  showing  that  Thibet  is  actually  a  large  valley  of  mountains,  and  not  a 
plateau,  have  put  it  beyond  doubt  that  the  cause  of  tlus  contrast  between 
the  snowy  slopes  must  be  sought  for  in  the  system  of  winds.  On  the 
north,  the  aerial  masses  which  sweep  over  the  Himalaya  after  having 
traversed  the  whole  of  Central  Asia  are  perfectly  dried  up  ;  but  on  the 
south,  the  monsoons  which  rush  stormily  through  the  gorges  of  Nepaul 
and  Sikkim  are  charged  with  an  enormous  burden  of  moisture,  which  falls 
in  snow  on  the  high  summits  and  in  rain  on  the  valleys  beneath. 

On  the  mountain  chains  which  extend  to  the  north  of  the  Himalaya 
the  mean  limit  of  perpetual  snow  descends  regularly  as  the  chains  lie  far- 
ther north.  In  the  Karakorum,  where  this  ideal  line  is  higher  than  in  the 
Himalaya,  on  account  of  the  great  dryness  of  the  air,  the  respective  alti- 
tudes are,  in  the  southern  chain  19,225  feet,  and  in  the  northern  slope 
18,438  feet;  in  the  Kouen-Lun  they  are,  on  the  south,  15,640  feet,  and 
14,960  feet  on  the  north.  As  regards  the  other  chains  of  Central  Asia 
no  exact  observations  have  been  made,  except  for  the  Altai,  in  Avhich  the 
mean  limit  of  perpetual  snow  is  at  7034  feet. 

•  In  a  general  way  it  is  allowed  that  about  the  75th  degree  of  north  lat- 
itude the  snow-limit  coincides  with  the  level  of  the  sea ;  but,  as  Richard- 
son has  shown,  no  arctic  regions  have  yet  been  discovered  which  in  the 
height  of  the  summer  are  covered  with  a  permanent  layer  of  snow,  and 
very  probably  none  such  exist.*  Therefoi-e,  as  regards  these  polar  coun- 
tries, as  well  as  for  most  of  the  mountains  in  the  temperate  zones,  the  ex- 
pression of  "  perpetual  snow"  ought  to  be  erased  from  scientific  phraseol- 
ogy. We  must  also  refrain,  notwithstanding  the  example  set  us  by 
many  meteorologists,  from  laying  down  any  general  law  in  reference  to 
the  mean  limit  of  snow ;  for  the  atmospheric  phenomena  in  the  various 
parts  of  the  world  are  not  yet  sufficiently  well  known,  and  the  distribu- 
tion of  heat,  the  direction  and  humidity  of  the  winds,  vary  quite  as  much 
as  the  fonns  of  the  continents  themselves. 

The  more  important  point,  therefore,  is,  not  the  mere  recognition  of  the 

uncertain  and  variable  line  of  the  lower  snow-limit  on  mountain  slopes, 

but  the  establishment,  as  regards  the  most  varied  points,  of  the  mean 

quantity  of  snow  which  falls  annually  on  the  sides  and  summits  of  mount- 

*  Vide  the  chapter  on  "Climates," 


VARIATION  IX  THE  SNOW-LINE.  157 

ains,  these  facts  being  derived  from  observations  carried  on  season  after 
season  and  year  after  year.  In  like  manner,  as  regards  a  river,  neither 
the  low-water  mark  nor  the  point  reached  by  the  highest  floods  is  the 
fact  which  is  the  most  essential  to  ascertain,  for  these  levels  relate  but  to 
an  instant  of  fluviatile  vitality,  and  their  sole  value  is  only  as  a  means 
of  comparison  with  other  such  levels ;  the  more  useful  questions  are  the 
mean  discharge  of  the  flow  of  water,  and  the  resultant  presented  by  the 
incessant  fluctuations  of  the  stream. 


103  ^^^  EAMTH. 


CHAPTER  XXIX. 

INFLUENCE  OP  THE  SUN  AND  METEOKIC  AGENTS  ON  THE  SNOAV. — ^^  AVA- 
LANCHES.  PKOTECTING  FORESTS.  —  DEFENSIVE  WORKS  AGAINST  DOWN- 
FALLS OF  AVALANCHES. 

The  accumulated  layers  of  snow  do  not  remain  forever  on  the  sides 
and  summits  of  mountains.  Since  every  year,  on  the  average,  33  feet  of 
snow  fall  on  the  mountains  of  the  Alps,  these  peaks  would,  in  fact,  in  the 
course  of  a  century,  increase  33,000  feet  in  height,  if  the  humidity  falling 
from  the  clouds  in  the  form  of  snow-flakes  was  not  evaporated  into  the 
atmosphere,  or  did  not  find  its  way  down  into  the  valleys  below. 

The  heat  of  the  sun  and  meteoric  influences  commence  the  work  of 
clearing  away  the  snow.  It  has  been  calculated  that  the  solar  rays  will 
melt  as  much  as  20  to  28  inches  of  snow  in  a  day,  especially  when  the  ■ 
upper  layers  are  not  very  dense,  and  allow  the  heat  to  penetrate  to  some 
depth  under  the  surface.  The  rain  and  tepid  mists  which  the  winds  con- 
vey on  to  the  mountain  slopes  also  lend  their  aid  in  thawing  the  snowy 
layers,  and  sometimes  indeed  with  more  eflcct  than  the  rays  of  the  sun. 
The  cold  winds  likewise  assist  by  blowing  up  the  snow  into  whirlwinds, 
find  thus  transferring  it  to  lower  slopes  where  the  temperature  is  higher. 
There  is  not  one  violent  wintry  squall  Jivhich  does  not  remove  thousands 
of  cubic  yards  of  snow  from  the  summits  of  lofty  mountains,  as  may 
easily  be  seen  from  below,  when  the  peaks  beaten  by  the  wind  appear  to 
smoke  Jike  craters,  and  the  powdered  flakes  are  dispersed  in  whirlwinds. 
The  warm  and  dry  winds,  however,  effect  still  more  than  storms  in  di- 
minishing the  masses  of  snow  which  lie  heavy  on  the  summits.  Thus  the 
south  wind,  which  is  called  fohn  by  the  Swiss  mountaineers,  will  in 
twelves  hours  melt  or  cause  to  evaporate  a  bed  of  snow  three  quarters  of 
a  yard  thick.  It  "  eats  up  the  snow,"  as  the  proverb  says,  and  brings 
spring  back  again  on  the  mountains.  Next  to  the  sun,  the  fohn  is  the 
principal  climatic  agent  in  the  Alpine  districts. 

It  would  be  very  important  if  we  could  establish  the  average  propor- 
tions of  the  masses  of  snow  which  fall  upon  the  mountains  which  are  lost 
by  melting  and  evaporation  respectively.  In  valleys  where  the  sides  are 
composed  of  hard  rocks  which  retain  the  water  on  the  surface,  it  would 
suffice  to  measure  the  annual  discharge  of  the  torrent,  and  to  compare  it 
with  the  quantity  of  rain-water  and  snow  which  has  fallen  in  the  basin 
during  the  same  period,  and  we  should  approximately  ascertain  all  that 
has  been  lost  en  route,  being  drawn  from  it  either  by  the  innumerable 
roots  of  the  plants  growing  in  it,  or  directly  by  evaporation.  At  all 
events,  it  is  certain  that  this  latter  cause  of  diminution  is  very  important. 


MELTING   OF  MOUNTAIN  SNOWS.  169 

for  even  during  calm  weather,  and  at  thi-ee  or  four  degrees  below  freez- 
ing-point, the  supei-iicial  surface  of  the  snow  constantly  supplies  to  the 
atmosphere  a  certain  portion  of  aqueous  vapor.  Under  the  influence  of 
the  sun  and  wind  evaporation  increases  very  rapidly. 

But  these  slow  and  gradual  means  are  not  the  only  causes  of  the  dimi- 
nution of  the  mountain  snows ;  they  also  sink  down  in  masses  into  the 
valleys,  and  thus  expose  themselves  directly  to  the  influence  of  heat. 
Tlie  masses  which  thus  rush  down  the  slopes  are  avalanches,  likewise 
called  in  the  Alps  lavanges  and  challanches.  The  greater  part  of  these 
downfalls  of  snow  occur  with  great  regularity,  so  much  so  that  an  old 
mountaineer,  who  is  clever  at  discerning  the  signs  of  the  weather,  can 
often  announce  by  a  mere  glance  at  the  surface  of  the  snow  the  exact 
time  at  which  the  subsidence  will  take  place.  The  path  of  the  avalanche 
is  completely  marked  out  on  the  mountain  side.  At  the  outlets  of  the 
wide  mountain  amphitheatres  in  which  the  snows  of  winter  are  accumu- 
lated, narrow  passages  open,  hollowed  out  in  the  thickness  of  the  rock. 
Like  torrents,  only  that  they  appear  but  for  a  moment  and  are  suddenly 
gone,  the  masses  of  snow  which  are  detached  from  the  upper  declivities 
rush  down  the  inclined  beds  aflbrded  them  by  the  narrow  passages,  and 
descend  in  long  trains,  until,  arrived  at  the  ledge  of  their  ravine,  they 
pour  out  over  the  slope  of  debris.  Most  mountains  are  furrowed  over  their 
whole  extent  with  vertical  channels,  down  which  the  avalanches  rush  in 
the  spring.  These  falling  masses  become  actual  tributaries  of  the  streams 
which  run  below ;  only,  instead  of  flowing  continuously  as  the  rivulets 
of  the  cascades,  they  plunge  down  all  at  once,  or  in  a  succession  of  falls. 

On  slopes  where  the  inclination  exceeds  50°,  the  snows  not  only  de- 
scend through  the  passages  hollowed  out  here  and  there  on  the  mountain 
sides,  but  they  also  slide  en  masse  over  the  escarpments.  Their  gradual 
progress  being  more  or  less  rapid,  at  first  they  accumulate  in  heaps  when 
they  meet  with  any  obstacle  in  the  less  sloping  portions  of  their  track, 
until,  becoming  animated  with  a  sufficient  momentum,  they  at  last  break 
forth  with  a  crash,  and  dash  down  into  the  depths  below.  The  particular 
way  in  which  each  avalanche  descends  is,  of  course,  varied  according  to 
the  shape  of  the  mountain.  On  perpendicular  escarpments  the  snow  on 
the  upper  terraces  is  slowly  impelled  by  the  pressure  of  the  masses  above 
it,  and  plunges  over,  straight  down  into  the  abyss  below.  In  spring  and 
summer,  when  the  white  layers,  softened  by  the  heat,  are  falling  away 
every  hour  from  the  lofty  summits  of  the  Alps,  the  mountain  climber, 
standing  on  some  adjacent  headland,  may  contemplate  with  admiration 
these  sudden  cataracts  dashing  down  into  the  gorges  from  the  heights  of 
the  shining  peaks.  How  many  thousands  of  travelers,  seated  at  their 
ease  on  the  grassy  banks  of  the  Wengemalp,  have  witnessed  with  excla- 
mations of  pleasure  the  avalanches  rolling  down  to  the  base  of  the  sil- 
very pyramid  of  the  Jungfrau  !  First  the  enormous  bed  of  snow  is  seen 
to  plunge  forth  like  a  cataract,  and  lose  itself  in  the  lower  stages  of  the 
mountain ;  whirlwinds  of  powdered  snow,  like  a  cloud  of  bright  smoke, 


170  ^^^  EARTH. 

rise  far  and  wide  into  the  atmosphere ;  and  then,  when  the  snow-cloud 
has  passed  away  and  the  whole  region  has  again  assumed  its  solemn 
calm,  the  thunder  of  the  avalanche  is  suddenly  heard  reverberating  in 
deep  echoes  in  the  mountain  gorges,  one  might  fancy  it  was  the  voice  of 
the  mountain  itself. 

All  these  downfalls  of  snow  are  phenomena  in  the  economy  of  mount- 
ains, no  less  regular  and  normal  than  the  flowing  of  the  rainfall  into  riv- 
ers, and  they  form  a  part  of  the  general  system  of  the  circulation  of  wa- 
ter in  every  basin.  But  in  consequence  of  the  superabundance  of  snow, 
its  too  rapid  melting,  or  some  other  meteorological  cause,  certain  excep- 
tional avalanches,  like  the  inundations  caused  by  river -floods,  produce 
most  disastrous  efiects  by  laying  waste  the  cultivated  grounds  on  the 
lower  slopes,  or  even  by  swallowing  up  whole  villages.  Catastrophes  of 
this  kind  and  the  falls  of  rocks  are  the  most  formidable  occurrences  in 
the  vitality  of  mountains. 

The  avalanches  known  under  the  name  of  poudreicses  are  those  most 
dreaded  by  the  inhabitants  of  the  Alps,  on  account  not  only  of  the  rav- 
ages immediately  arising  from  them,  but  also  of  the  whirlwinds  which 
frequently  accompany  them.  Before  the  newly -fallen  layers  of  flakes 
sufiiciently  adhere  to  the  former  snow,  the  mere  tread  of  the  chamois, 
the  fall  of  a  branch  from  some  bush,  or  even  a  resounding  echo,  is  sufii- 
cieut  to  disturb  the  unstable  balance  of  the  upper  sheet  of  snow.  At 
first  it  slides  slowly  over  the  hardened  mass  beneath,  until,  reaching  a 
point  where  the  slope  of  the  ground  assists  its  progress,  it  rushes  down 
with  an  increasingly  rapid  movement.  Every  moment  it  becomes  aug- 
mented by  fresh  beds  of  snow,  and  by  the  debris,  stones,  and  brush-wood, 
which  it  hurries  along  with  it.  It  makes  its  way  over  the  ledges  and 
passages,  tears  down  the  trees,  sweeps  away  the  chalets  which  lie  in  its 
path,  and,  like  the  downfall  of  the  side  of  a  mountain,  plunges  into  the 
valley,  sometimes  even  reaching  the  opposite  slope.  All  round  the  ava- 
lanche powdery  snow  rises  in  broad  eddies ;  the  air,  being  compressed 
laterally  by  the  sinking  mass,  roars  right  and  left  in  actual  whirlwinds, 
which  shake  the  rocks  and  uproot  the  trees.  Thousands  of  trunks  may 
sometimes  be  seen  thrown  down  by  nothing  but  the  wind  of  the  ava- 
lanche, when  the  latter  traces  out  for  itself  a  wide  path  across  whole  for- 
ests, and,  as  it  passes,  sweeps  away  the  hamlets  in  the  valley.* 

The  avalanches  de  fond  are  generally  less  dangerous  than  those  we 
have  just  spoken  of,  because  they  are  formed  at  a  more  advanced  season 
of  the  year,  when  the  greater  part  of  the  superficial  snow  is  melted,  and 
the  remainder  of  the  mass  is  able  to  run  through  its  regular  passages. 
As  their  name  indicates,  these  avalanches  are  composed  of  the  whole 
thickness  of  the  snow-field.  Lubricated,  as  it  were,  by  the  rivulets  of 
water  which  cross  them  and  flow  over  them,  the  beds  of  snow  lose  their 
adherence  to  the  ground,  and  slide  in  one  lump,  like  marine  icebergs  de- 
taching themselves  from  a  field  of  ice.  Under  the  pressure  of  these  mov- 
*  Tschudi,  Le  Monde  des  Alpes,  vol.  ii. 


DEFENSES  AQAMST  AVALANCHES.  171 

iug  masses,  the  snow  below  at  last  yields,  and  the  avalanche,  loaded  with 
water  and  mud,  earth  and  stones,  rushes  through  the  passages  and  over 
the  rocks ;  at  last,  finding  its  way  into  the  valley,  it  dams  up  the  stream 
with  a  kind  of  dike,  which  sometimes  resists  the  weight  of  the  water  till 
the  middle  of  summer,  and  the  gray  or  even  blackish  mass  becomes  so  com- 
pact that  it  assumes  the  hardness  of  rock.  It  is,  in  fact,  a  glacier  in  miniature. 

Thickly-planted  trunks  of  trees  are  the  best  protection  against  ava- 
lanches of  every  kind.  In  the  first  place,  the  snow  which  has  fallen  in  the 
wood  itself  can  not  very  well  shift  its  place ;  and  then,  when  the  masses 
descending  from  the  slopes  above  dash  against  the  trees,  they  are  unable 
to  break  through  so  strong  a  barrier.  After  having  overturned  some  few 
of  the  first  trees,  their  progress  is  arrested,  and  the  intermingled  heaps 
constitute  a  fresh  obstacle  for  future  avalanches.  Small  shrubs,  such  as 
rhododendrons,  or  even  heaths  and  meadow  grass,  are  very  often  sufiicient 
to  prevent  the  slipping  of  the  snow,  and  where  people  are  imprudent 
enough  to  cut  them  on  the  mountain  slopes,  they  run  the  risk  of  clearing 
the  Avay  for  this  formidable  scourge.  The  danger  is  still  more  imminent 
if  a  screen  of  trees  is  cut  down  in  one  of  the  protecting  forests.  The  task 
is  then  begun  for  the  avalanche,  which  soon  undertakes  to  complete  the 
rest  of  the  labor  by  tearing  up  all  that  still  remains  of  the  former  woody 
rampart.  A  mountain  which  stands  to  the  south  of  the  Pyrenean  village 
of  Aragnouet,  in  the  lofty  valley  of  the  Neste,  having  been  partially 
cleared  of  trees,  a  tremendous  avalanche  fell  down,  in  1846,  from  the  top 
of  a  plateau,  and  in  its  fall  swept  away  more  than  15,000  fir-trees. 

The  protecting  woods  of  Switzerland  and  the  Tyrol  used  to  be  defend- 
ed by  the  national  bann^  and,  as  it  were,  "  tabooed."  They  were,  and 
still  are,  called  the  Bannwmlder.  In  the  valley  of  Andermatt,  at  the 
northern  foot  of  the  St.  Gothard,  the  penalty  of  death  was  once  adjudged 
on  any  man  found  guilty  of  having  made  an  attempt  on  the  life  of  one  of 
the  trees  which  shielded  the  habitations.  Added  to  this,  a  sort  of  mystic 
curse  was  thought  to  hang  over  this  impious  action,  and  it  was  told  with 
horror  how  drops  of  blood  flowed'  when  the  smallest  branch  was  broken 
off.  It  was  true  enough  that  the  destruction  of  each  tree  might  perhaps 
be  expiated  by  the  death  of  a  man. 

The  inhabitants  of  some  villages  which  are  threatened  with  avalanches 
endeavor  to  find  a  substitute  for  trees  in  long  stakes  or  piles  driven  into 
the  ground  to  resemble  fir-trees.  This  is  what  they  call  clouer  V avalanche 
(nailing  up  the  avalanche).  At  the  same  time,  they  hew  steps  at  inter- 
vals, almost  like  a  staircase,  so  that  the  snow  falling  from  the  cliffs  may 
be  arrested  in  its  course  or  partially  broken  up.  In  some  localities,  too, 
they  construct  lateral  walls  on  purpose  to  contain  the  flow  of  the  ava- 
lanche, as  if  it  were  a  banked-up  river;  and  if,  after  all  these  precautions, 
the  houses  are  still  threatened,  they  furnish  them,  like  the  piles  of  a  bridge, 
with  spurs  or  buttresses,  made  of  stone  or  hardened  snow,  which,  by 
sprinkling,  is  gradually  changed  into  ice,* 

*  William  Huber,  Les  Glaciers, 


172  THE  EARTH. 

The  village  and  the  great  establishment  of  the  baths  at  Bareges,  in  the 
Pyrenees,  used  to  be  menaced  every  year  by  avalanches  rushing  down 
from  an  elevation  of  4000  feet,  at  an  angle  of  35  degrees.  The  inhabit- 
ants, therefore,  were  in  the  habit  of  leaving  vacant  spaces  between  the 
two  quarters  of  Bareges,  so  as  to  allow  a  free  passage  to  the  descending 
masses.  Lately,  however,  they  have  endeavored  to  do  away  with  the 
avalanches  by  means  somewhat  similar  to  those  employed  by  the  Swiss 
mountaineers.  They  have  thrown  up  banks  about  10  or  12  feet  broad 
on  the  sides  of  the  ravines,  and  have  furnished  these  banks  with  an  edg- 
ing of  cast-iron  piles.  Basket-work,  and,  here  and  there,  walls  of  mason- 
ry, protect  the  young  growing  trees,  which  are  gradually  improving  un- 
der the  protection  of  these  defensive  works.  In  the  mean  time,  until  the 
real  trees  are  strong  enough  to  arrest  the  course  of  the  snow,  the  artificial 
trees  have  well  fulfilled  the  end  they  were  destined  for.  In  1860,  the 
year  when  the  defensive  works  were  finished,  the  only  avalanche  which 
slid  into  the  ravine  did  not  exceed  400  cubic  yards  in  bulk;  while  the 
masses  which  used  to  fall  down  upon  Bareges  sometimes  attained  to  more 
than  90,000  yards  in  volume. 


CHANGE  OF  SNOW  INTO  ICE. 


173 


CHAPTER  XXX. 

GRADUAL  TRANSPORMATIOX  OF  SNOW  INTO  ICE. — NEVES,  OR  GLACIER-RES- 
ERVOIRS.— PHENOMENON  OF  REGELATION.— CRYSTALS  OF  ICE. — GLACIERS 
OF  THE  FIRSf  AND  SECOND  ORDER. 

By  a  succession  of  partial  changes  affecting  the  millions  of  frozen  par- 
ticles, the  snow  of  the  high  mountain  summits  is  changed  into  ice,  and 
the  white  flakes  falling  on  the  peaks  become  those  rivers  of  bluish  crys- 
tal which  slowly  make  their  way  down  between  the  sides  of  the  gorges. 
Imperceptibly  the  field  of  snow  is  changed  into  wewe,  and  then  into  gla- 
cier ;  afterward  becoming  in  succession  stream,  river,  and  wave,  it  finally, 
under  the  form  of  aqueoys  vapor,  recommences  its  eternal  circuit. 

The  alteration  of  opaque  snow  into  transparent  ice  is  one  of  the  most 
interesting  phenomena  of  planetary  vitality.  The  newly-fallen  flakes  be- 
gin by  first  settling  down  and  hardening.  Then,  when  the  rays  of  the 
sun  have  raised  the  temperature  of  the  snow-field  to  melting-point,  a 
number  of  small  drops  penetrate  into  the  subjacent  layers,  and,  being 
again  assailed  by  the  cold,  freeze  into  small  envelopes,  irregularly-crys- 
tallized round  solid  molecules,  and  become  cemented  all  together  into  a 

compact  mass.  The  snow  may  thus  become 
very  hard,  and  on  the  edge  of  many  of  the 
precipices  it  forms  a  kind  of  overhanging  pent- 
house, which  resists  for  a  considerable  time 
the  effects  of  the  weather  without  giving  way. 
We  borrow  from  Forbes  the  design  of  one  of 
these  elegant  cornices,  with  its  brilliant  pend- 
ants of  ice. 

In  the  end,  the  entire  thickness  of  the  snow- 
field  changes  its  structure  and  becomes  a  mass 
of  granules,  from  which  the  air  is  partially  ex- 
pelled by  the  successive  "freezing  and  melting 
produced  by  the  solar  heat.  In  this  way  are 
formed  the  hard  and  granular  beds  of  former  snow,  which  lie  upon  the 
upper  slopes  of  all  lofty  mountains ;  these  whitish  or  dull  gray  masses 
are  known  in  the  Alps  and  Pyrenees  by  the  name  of  neves.  In  winter, 
when  the  temperature  often  remains  below  the  freezing-point,  even  during 
the  day-time,  the  snow  on  high  summits  maintains  its  powdery  state ;  but 
as  soon  as  it  is  subjected  to  the  first  breath  of  spring,  it  begins  to  assume 
a  granular  form.* 
The  first  change  in  the  particles  of  snow  is  but  the  prelude  to  still 

♦  Desor,  NtuveUe^  Excursions  et  Sf jours  dans  les  Glaciers. 


Ftg.45.  Coniice  ofSnow. 


174  *  THE  EARTH. 

more  important  modifications.  The  heat  of  the  sun  continues  to  melt 
the  surface-layers,  and  thus  causes  drops  of  water  and  laminje  of  ice  of 
an  increasing  size  to  penetrate  into  the  neve.  Simultaneously  the  snow, 
compressed  by  its  own  weight,  ultimately  expels  by  mechanical  force  the 
greater  part  of  the  air  which  it  contains,  and  gives  to  the  opaque  granules 
of  the  ncv'e  the  structure  and  transparency  of  ice.  The  pressure  of  the 
superincumbent- layers  is  the  pnncipal  agent  in  the  transformation  of  beds 
of  snow.  The  brothers  Schlagintweit  and  Tyndall  state  that  by  the  com- 
pression of  fresh  snow  they  succeeded  in  obtaining  slabs  of  transparent 
ice ;  but  there  is  scarcely  a  child  who  has  not  amused  himself  in  trying 
the  same  experiment  by  kneading  a  snow-ball  with  his  fingers.  Under 
the  tread  of  the  pedestrian,  the  coating  of  snow  which  sticks  to  his  shoes 
ultimately  becomes  a  piece  of  ice.* 

In  consequence  of  this  gradual  transformation,  the  mass  of  weye  becomes 
more  and  more  indurated  and  compact.  A  cubic  yard  of  snow  weighs 
on  the  average  187  lbs.;  but  the  same  volume  of  neve  weighs  more  than 
half  a  ton,  and  the  various  modifications  to  w^ich  the  snow  is  subject 
in  becoming  transparent  ice  ultimately  give  it  a  weight  of  about  1980 
lbs.  per  cubic  yard.  The  material  which  constitutes  the  glaciers  is  twelye 
times  lighter  than  water  when  it  commences  its  course,  but  at  the  end  of 
its  career  it  is  only  one  tenth  or  one  twentieth  part  inferior  in  weight  to 
an  equal  liquid  volume.f 

Notwithstanding  these  successive  changes,  the  whole  thickness  of  the 
mass  of  neve  is  composed  of  strata  of  varying  regularity,  which  are  the 
beds  of  snow  deposited  in  successive  winters.  Each  of  the  superimposed 
beds  exhibits  on  its  surface  a  kind  of  gray  or  yellowish  crust,  which  is 
formed  by  the  mixture  with  the  snow  of  bits  of  stone,  dust,  and  even  the 
remains  of  insects ;  under  this  crust  extends  a  thin  layer  of  glazed  ice, 
caused  by  the  freezing  of  the  water  which  had  melted  on  the  surface. 
The  strata  of  the  neve,  being  thus  arranged  one  above  the  other  like  the 
beds  in  a  calcareous  rock,  are,  in  proportion  to  their  age  and  the  weight 
that  is  laid  upon  them,  all  the  more  compact  and  ice-like  in  their  texture. 
In  many  places  these  strata  may  be  perceived  at  the  edge  of  the  neve; 
for  wherever  the  rocks  rise  above  the  upper  snow-limit  a  kind  of  cleft 
may  be  noticed  in  the  nev^,  owing  partly  to  the  rending  force  exercised 
by  the  whole  mass  .on  the  upper  beds,  and  still  more,  perhaps,  to  the 
flowing  of  the  water  which  trickles  round  the  base  of  the  rocks  which 
are  warmed  by  the  sun. 

Below  the  neve,  which  is,  in  fact,  the  reservoir  in  which  the  ice  begins 
to  form  which  afterward  is  to  feed  the  glacier  properly  so  called,  the 
frozen  masses  continue  to  become  gradually  modified  as  regards  their 
internal  structure.  It  is  very  true  that  a  great  part  of  the  ice,  which  is 
melted  by  the  rays  of  the  sun,  the  rain,  or  the  mild  breath  of  warm  winds, 
remains  in  a  liquid  state,  and  in  the  form  of  rivulets  finds  its  way  through 

*  "William  Huber,  Les  Glaciers. 

t  Dollfiiss-Ausset,  Materiaux  pour  servir  a  V Etude  des  Glaciers. 


FORMATION  OF  GLACIERS.  175 

the  crevices  of  the  glacier,  and  joins  the  stream  which  flows  over  the 
rocks'  below.  But  there  is  another  agent  at  work  as  well  as  the  sun  in 
the  process  of  melting  the  ice  in  the  very  heart  of  the  layers.  This 
agent  is  the  pressure  exercised  by  the  upper  masses  on  the  ice  lying 
beneath  them. 

Natural  philosophers  have,  in  fact,  proved  that  the  melting  temperature 
of  ice  lowers  forty-two  ten  thousandths  of  a  degree  (Fahr.)  for  every  at- 
mosphere of  pressure.  At  the  foot  of  rapid  slopes,  where  the  enormous 
weight  of  the  layers  above  compresses  the  ice  with  the  force  of  a  large 
number  of  atmospheres,  the  liquefying  point  of  the  mass  is  considerably 
lowered,  a  greater  or  less  amount  of  latent  heat  is  set  free,  and  a  portion 
of  the  ice  must  melt  and  pass  into  water.  Thus,  in  consequence  of  this 
pressure,  cells  and  liquid  veins  are  here  and  there  opened  in  the  interior 
of  the  glacier,  the  mean  heat  of  which  is,  however,  only  a  mere  fraction 
of  a  degree  lower  than  the  freezing-point.  The  protracted  and  numerous 
experiments  of  Agassiz  have  proved  that  in  a  deep  hole  sunk  to  a  depth 
of  200  feet  in  solid  ice  the  thermometer  marked  on  the  average  31°  24' 
(Fahr,),  and  that  only  in  winter,  and  quite  exceptionally,  the  temperature 
was  lowered  to  28°  24'  (Fahr.) ;  in  the  opexi  air  the  cold  was  most  intense. 
Owing,  therefore,  to  the  comparatively  high  temperature  of  the  ice,  small 


Fig.  46.  Internal  banded  Stnictnre  of  Ice. 

veins  of  water  are  formed  which  penetrate  its  entire  mass,  Nevertheless, 
the  particles  of  ice  which  divide  the  thin  films  of  water  remain  separate 
only  for  an  instant ;  for  even  under  a  slight  pressure,  very  much  less  than 
that  which  is  brought  to  bear  upon  glaciers,  two  morsels  of  ice  suiTOuuded 
by  water  immediately  approach  one  another,  and  unite  to  form  a  single 
lump.  Even  in  warm  water  two  pieces  of  ice  which  are  melting  continually 
strive  to  combine,  and  the  isthmus  which  joins  them  forms  and  reforms 
until  the  last  solid  particles  have  disappeared.  This  is  the  great  fact 
which  was  discovered  by  Faraday,  and  brilliantly  demonstrated  by  Tyn- 
dall,  who  has  given  it  the  name  of  regdation.  This  phenomenon  takes 
place  at  every  point  in  the  thickness  of  the  glacier.  Particles  of  ice 
approach  one  another,  and  unite  across  the  little  veins  of  water  which 
permeate  it  in  every  direction-;  fresh  liquid  films  are  formed  under  the 
pressure  above;  fresh  unions  take  place  between  the  divided  morsels  of 
ice ;  and,  by  this  continual  process  of  change,  the  air  contained  in  the 
mass  of  that  which  once  waft  snow  is  gradually  expelled.  Thus  it  happens 
that  the  whole  mass  ultimately  assumes  an  almost  perfect  transparency 
and  a  beautiful  azure  color.  It  is,  however,  the  case  every  winter  that 
*  A  weight  equivalent  to  that  of  a  column  of  water  of  about  32  feet. 


176 


THE  EARTH. 


the  clefts  on  the  surface  of  the  glaciers  are  filled  up  with  fresh  masses  of 
snow.  These  new  layers,  to  which  an  intermixture  of  air-bubbles  gives 
a  whitish  tint,  are  dragged  and  thrown  forward  by  the  general  move- 
ment. In  several  glaciers,  where  mighty  crevasses  disclose  the  internal 
structure  of  the  whole  mass,  it  is  wonderful  to  see  the  alternate  stratifica- 
tions of  gray  snow  and  the  blue  belts  of  ice,  just  like  the  beds  of  a  forma- 
tion of  rocks.  On  high  elevations  neve  and  glacier  are  intermingled 
together.  In  climbing  Monte  Rosa,  Zumstein  saw,  down  in  a  crevasse  of 
neve,  real  glacier  ice,  at  a  height  of  13,989  feet,  less  than  1300  feet  below 
the  summit. 

Nevertheless,  whatever  may  be  the  modifications  which  the  snow  un- 
dergoes, it  is  a  matter  of  fact  that,  even  in  the  lower  parts  of  glaciers, 
granules  are  found  similar  to  those  of  the  neve,  only  these  grains  have  be- 
come transparent  and  free  of  air-bubbles,  and  in  their  long  course  toward 
the  valleys  have  considerably  increased  in  size.  Some  of  them  are  as 
large  as  a  chestnut,  or  even  a  hen's  eo^o,.  These  granules  of  ice  are  some- 
times very  irregular  in  shape,  owing  to  the  enormoiis  pressure  to  which 
they  have  been  subjected,  sometimes  in  one  direction  and  sometimes  in 
another;  but  the  phenomena  of  polarization  which  they  present  to  the 
light  prove  that  they  are  really  crystals,*  and  the  whole  glacier  is  an  ac- 
cumulation of  granules  confusedly  packed  together.  From  tlie  moment 
when  the  snow-flakes  fall  in  the  shape  of  needles  and  stars,  to  the  time 
when  they  are  reared  up  in  blue  walls,  it  never  ceases,  under  all  its  va- 
rious aspects,  to  retain  a  crystalline  character. 

The  snows  which  are  thus  transformed  into  ice  by  the  efiects  of  press- 
ure form  the  enormous  masses  which  cover  the  mountain  sides  and  fill 
up  whole  valleys.  Some  of  these  glaciei's — those  of  the  Pyrenees,  for  in- 
stance— only  extend  over  the  upper  slopes  of  the  mountain,  and  do  not 
descend  through  the  gorges  as  far  as  the  cultivated  grounds  at  its  base. 
These  are  the  glaciers  which  Saussure  calls  Secondary  or  summit  glaciers. 
There  are  other  fields  of  ice  which  also  take  their  rise  on  lofty  peaks,  and, 
flowing  out  into  the  mountain  amphitheatres,  make  their  way  into  the 
lower  valleys,  uniting,  on  each  side  of  their  beds,  with  the  ice  of  other 
tributary  gorges;  these  are  glaciers  of  the  first  order.  There  are  some 
which  extend  to  a  length  of  12,  18,  or  30  miles,  and  attain  a  thickness  of 
several  hundred  yards.  These  are  easy  to  class;  but  in  nature  the  transi- 
tions are  so  gradual  that,  as  regards  the  greater  number  of  glaciers,  it  is 
impossible  to  point  out  precisely  in  which  category  they  ought  to  be 
classed.     The  distinction  established  by  geologists  is  purely  artificial. 

*  Sonklar,  (Etztkaler  Gebirgsgruppe. 


£Xr£IiIMtWTS.  177 


CHAPTER  XXXL 

ilOVEMENT   OF   GLACIERS. — EXPERIMENTS   AND    THEORIES. CONVEXITY   OF 

THE  CENTRAL  PART  OF  A  GLACIER. — ITS  SUCCESSIVE  WINDINGS. — FRIC- 
TION OF  THE  ICE  AGAINST  THE  BOTTOM  AND  SIDES  OF  THE  BED. — THE 
GLACIER   GAUGE. — INCLINATION   OF   THE    GLACIER   BED. 

The  Alpine  mountaineers,  from  time  immemorial,  have  been  aware  of 
the  fact  that  glaciers  move  onward,  and  convey  masses  of  rock  from  the 
mountain  summits  down  into  the  valleys ;  but  it  was  unknown  to  most 
geographers,  shut  up  as  they  were  in  their  gloomy  studies.  At  the  end 
of  the  sixteenth  century,  Simmler  announced  this  marvelous  fact,  and 
other  savants  repeated  it  after  him ;  but  it  was  not  generally  known  until 
the  end  of  the  last  century,  after  the  publication  of  Horace  de  Saussure's 
travels.  This  traveler,  one  of  the  first  of  that  generation  of  energetic 
men  who  knew  well  how  to  combine  scientific  inquiry  with  skill,  strength, 
and  endurance,  and  could  also  both  hit  upon  and  unravel  the  mysteries 
of  nature,  verified  the  movement  of  glaciers,  and  attempted  to  propound 
a  theory  for  it.  He  was,  however,  content  with  stating  his  ideas  in  a 
general  way,  without  making  any  direct  experiments  to  verify  them. 

This,  however,  fell  to  the  share  of  Hugi,  In  1827  he  had  a  little  hut 
built  on  the  glacier  Unteraar,  at  the  foot  of  the  promontoiy  of  Ab- 
schwung.  In  1830  the  hut  was  110  yards  lower  down;  by  1830  it  had 
traveled  780  yards;  by  1841  it  had  reached  a  distance  of  1561  yards 
from  its  first  position ;  its  movement,  therefore,  had  been  at  the  rate  of 
112  yards  a  year.  Since  that  date,  a  great  number  of  experiments  of  the 
same  kind  have  been  made  by  other  explores.  The  measurements  made 
so  carefully  by  Agassiz  on  the  upper  tributaries  of  the  same  glacier,  the 
Aar,  the  Finsteraar,  and  the  Lauteraar,  have  proved  that  the  two  masses 
have  shifted  their  places,  one  from  52  to  89  yards,  the  other  from  34  to 
81  yards  each  year,  according  to  the  various  positions  of  the  measure- 
ment-marks on  the  surface  of  the  glacier.  The  motion  was  ascertained  to 
be  the  more  rai)id  in  proportion  as  the  marks  were  nearer  the  central  poi-- 
tion  of  the  field  of  ice.  Thus  this  important  fact  was  brought  to  light, 
that  the  mass  of  the  glacier  occupying  the  centre  of  the  bed  descends 
more  quickly  than  the  portion  situated  in  the  vicinity  of  the  two  sides. 
Hencefoith  the  matter  was  set  at  rest  that,  without  any  exaggeration  of 
language,  a  glacier  might  be  literally  assimilated  to  a  river.*  This,  how- 
ever, is  an  idea  that  had  already  been  suggested  by  M.  Rendu,  an  excel- 
lent observer  of  the  mountains  of  Savoy.  In  a  work  on  glaciers,  i)ub- 
lished  in  1841,  he  stated  that  there  was  a  pci-fect  resemblance  between 
the  Mer-de-Glace,  in  Savoy,  and  a  river,  and  that  it  would  be  impossible 
•*  Compter  Rendua  de  rAcadimie  des  Sciences,  29th  of  August,  1842. 

M 


178  ^^^  EARTH. 

to  point  out  any  phenomenon  in  any  of  the  streams  which  might  not  be 
found  in  the  other. 

To  what  cause,  therefore,  are  we  to  attribute  this  gradual  descent  of 
the  river  of  ice  in  its  rocky  bed  ?  At  all  events,  it  is  certain  that  it  is 
not  a  mere  sliding  of  the  mass  over  its  lubricated  bed,  for  it  has  been 
several  times  proved  that  above  the  zone  in  which  the  mean  temperature 
of  the  gi'ound  is  below  the  freezing-point,  that  is,  at  about  the  height  of 
6600  feet  in  the  Central  Alps,  the  layers  of  the  glacier  are  frozen  to  the 
ground,  and  can  not  detach  themselves  from  it  by  the  mere  force  of  grav- 
ity. On  their  lower  surface  they  melt  but  slowly,  except  at  the  spot 
where  the  rivulet  flows,  which  gathers  all  the  surface-water  sinking 
through  the  crevasses.  There  are  also  instances  of  a  stream  running  by 
the  side  of  a  glacier  from  the  neve  to  the  terminal  moraines  without  be- 
ing able  to  penetrate  the  solid  wall  of  ice  adhering  to  its  bed  of  rocks.* 

Since  the  investigations  and  experiments  of  Tyndall,  it  has  become 
more  than  probable  that  the  real  cause  of  the  onward  motion  of  rivers  of 
ice  must  be  sought  for  in  the  formation  of  innumerable  fissures,  and  in 
the  reconstitution  of  all  the  broken  fragments  into  a  fresh  mass.  Regela- 
tion  is  taking  place  in  every  part  of  the  glacier  at  once,  and,  as  may  be 
easily  understood,  the  particles  of  ice  compressed  by  the  masses  above 
them  must  always  move  in  the  direction  of  the  slope  when  they  shift 
their  position  in  order  to  coalesce  anew.  This  descending  movement  and 
the  junction  of  the  particles  are  taking  place  at  the  same  time  as  regards 
millions  and  millions  of  broken  granules,  and  from  this  very  cause  the 
whole  body  of  the  glacier  descends  in  the  gorge  Avhich  serves  as  its  bed. 
Under  the  pressure  of  the  enormous  weight  which  pushes  it  forwai'd,  the 
ice  ultimately  becomes  so  moulded  as  to  fit  perfectly  into  its  channel  of 
rocks,  just  as  if  it  were  a  pasty  mass.  If  the  gorge  becomes  narrow,  the 
glacier  assumes  a  moi*e  elongated  shape  in  order  to  make  its  way  into 
the  defile ;  if  the  mountain  sides  widen  out  in  a  basin,  the  glacier  spreads 
out  like  a  lake  in  the  broad  hollow.  This  remarkable  plasticity  of  the  ice 
under  pressure  has  caused  several  distinguished  natural  philosophers  (as 
James  Forbes)  to  believe  that  the  frozen  mass,  although  so  brittle,  is  of  a 
viscous  nature,  and  flows  in  the  same  way  as  treacle  and  honey. 

Spring-time  is  the  season  in  which  the  river  of  ice  descends  toward  the 
valley  with  the  greatest  rapidity.  Then  the  phenomena  of  liquefaction 
and  regelation  take  place  with  the  greatest  frequency  on  the  elevated 
nive.  Innumerable  rivulets  of  water,  set  free  from  their  icy  prison,  widen 
the  crevasses  and  lubricate  the  slopes  on  which  the  solid  river  has  to  glide 
slowly  down.  The  blocks  of  ice,  glued  to  the  sides  of  their  bed  by  the 
frosts  of  winter,  regain  their  liberty.  It  is  probable  that  in  summer  the 
progress  of  a  glacier  is  at  least  double  as  fast  as  it  is  during  the  cold  sea- 
son. Thus,  according  to  Tyndall,  the  progress  of  the  Mer-de-Glace,  near 
Montanvers,  is  on  the  average  about  13  inches  a  day  in  winter,  and  more 
than  24^  inches  a  day  in  the  summer ;  but,  between  the  extreme  rates  of 
speed,  the  diSerence  is  much  more  considerable.  Every  variatien  of  tem- 
*  Sonklar,  (Etzthaler  Gehirgsgruppe. 


THE  MER  DE  GLACE    &    ITS   AFFLUENTS  pija 


»":»0T  ..!  Par.s 


»:!»<> 


En^d  K    Eri--- 


after  th«   Map  at'  M.  Hieulet. 


HAPFEF    *.  BROTH FPS    Ni:"vV  YORK 


OLACIERS''  CONVEXITY.  I79 

perature,  however,  makes  itself  felt  in  the  progress  of  the  glacier,  and  al- 
though experiments  do  not  all  agree  on  this  point,  it  is  probable  that  at 
sunset  the  glacier  slackens  its  course,  and  accelerates  it  again  when  the 
luminary  reappears  above  the  ridges  of  the  mountains ;  in  the  depths,  as 
on  the  surface,  the  sun  imparts  life  and  animation.  As  soon  as  the  early 
rays  of  day-breflk  have  lighted  up  the  glacier,  its  very  nature  seems  altered. 
Just  as  in  the  adjoining  forest,  the  field  of  ice  is  harmonious  with  a  thou- 
sand small  yet  joyous  sounds ;  the  little  drops,  falling  on  the  projections 
in  the  crevasses^  tinkle  as  they  are  broken  up ;  the  gradually-forming  riv- 
ulet murmurs  on  its  way ;  the  slopes  of  gravel  crumble  down  into  the 
crevasses ;  and  here  and  there  some  block,  uncemented  from  its  icy  ped- 
estal, roars  as  it  rolls  down  the  incline.  All  these  voices  of  the  glacier 
gain  strength  as  the  sun  gets  higher  in  the  horizon :  but  if  a  thick  cloud 
suddenly  interrupts  the  solar  rays,  silence  is  gradually  re-established,  and 
the  glacier  waits  for  the  return  of  the  sun  ere  it  resumes  its  song.  The 
enormous  ice-river  seems  endowed  with  vitality;  so  much  so  that  some 
enthusiastic  savants,  as  Hugi,  have  seriously  asked  the  question — whether 
the  monster  did  not  possess  a  soul  ?  Numbers  of  mountaineers,  in  all 
their  simplicity  of  mind,  fully  believe  it.* 

Just  as  in  liquid  rivers,  a  raising  up  of  the  central  portion  of  the  glacier 
corresponds  in  general  to  the  highest  rate  of  speed  in  the  moving  mass. 
The  convexity  of  the  surface  of  the  icy  stream  must  not  be  attributed  to 
an  afflux  of  the  whole  body  toward  the  middle;  the  cause  is,  perhaps,  the 
fact  that  the  central  parts,  being  animated  by  a  more  rapid  motion,  have 
not  had  sufficient  time  to  evaporate  and  melt  in  as  large  quantities  as 
those  at  the  sides,  which  are  slower  in  their  progress,  and  more  intersect- 
ed with  crevasses.  Sometimes,  however,  it  is  the  case  that  the  glacier  ex- 
hibits an  exactly  contrary  outline,  and  is  hollowed  out  like  a  gutter  in 
the  central  part.  This  happens  when  immense  moraines  cover  a  broad 
surface  of  the  ice  on  each  side,  and  hinder  their  melting.  An  instance  of 
this  fact  is  to  be  found  in  the  glacier  of  Vernagt,  in  the  (Etzthal.f 

Not  only  does  the  river  of  ice  act  exactly  like  a  liquid  water-course  by 
its  waves  rolling  on  with  much  more  rapidity  in  the  central  portion  than 
at  the  edges,  but,  similarly  to  all  other  rivers,  it  assumes  the  greater 
amount  of  force  in  its  current  at  the  convex  side  of  its  successive  wind- 
ings. Theory  would  have  beforehand  presumed  this  fact,  which,  however, 
the  experiments  of  Tyndall  in  1857  have  indubitably  established.  His 
measurements,  very  carefully  made  across  the  various  curves  of  the  Mer- 
de-Glace,  have  proved  that  the  thread  of  the  current  shifts  its  position  al- 
ternately to  the  right  and  left  of  the  medial  line,  and  approaches  each  of 
the  sides  in  turn,  sometimes  one,  sometimes  the  other.  Thus  the  axis  of 
movement  follows  an  undulating  line,  the  windings  of  which  are  more  de- 
cided even  than  those  of  the  gorge  of  the  glacier.  The  ideal  progress  of 
the  frozen  river  is  represented  by  the  illustration  on  the  following  page, 
which  would  apply  equally  to  the  current  of  a  liquid  river. 

♦  De  Chaqjentier,  Etaai  sur  let  Glaciers.  t  Vide  inserted  Plate,  XIV. 


180 


THE  EARTH. 


Fig.  47.  Windings  of  a  Glacier. 


The  same  caiise  which  impedes  the  motion  of  a  glacier  at  the  edges — 
that  is,  the  friction  of  the  sliding  mass  against  the  rocks — equally  dimin- 
ishes the  rapidity  of  its  current  along  its  bed.  In  this  point,  also,  the  ac- 
tion of  a  glacier  is  perfectly  analogous  to  that  of  a  river  moving  at  a  slow 
pace.  Forbes  and  M.  Martins  have  proved  this  on  the  Mer-de-Glace  and 
the  Faulhorn,  by  experiments  which  Tyndall  has  since  renewed  at  the 
risk  of  his  life.  Descending  the  sides  of  a  precipice  137  feet  in  depth, 
opening  between  the  rocks  and  the  glaciers  of  the  Tacul  (Mont  Blanc), 
he  succeeded  in  fixing  three  pegs  at  the  summit,  at  the  middle,  and  at  the 
base  of  the  vertical  wall  of  ice,  so  that  he  should  be  able  to  measure  their 
respective  rates  of  progress  two  days  afterward. 

The  upper  peer  had  advanced  54^  inches  in  the  twen-  x^'^^^B. 

ty-four  hours ;  the  middle  one,  fixed  36  feet  above 
the  bottom,  had  only  moved  onward  4  inches  in  the 
same  space  of  time ;  lastly,  the  lower  mark,  fixed 
more  than  a  yard  above  the  rocky  bed  of  the  gla- 
cier, had  only  progressed  at  the  rate  of  2^  inches  a 
day.*  Added  to  this,  in  certain  places  tlie  cascades 
of  surface-water  cut  out  ledges  resembling  steps  in 
the  sides  of  the  crevasses,  which,  as  it  were,  bring 
before  the  eye  the  superior  rapidity  of  the  upper 
layers  of  the  ice.  The  water  falls,  in  the  first  place, 
on  some  projection,  which  it  hollows  out  in  the 
shape  of  a  basin ;  but,  in  consequence  of  the  on- 
ward motion  of  the  glacier,  the  liquid  column  soon  ('.vx''>'^ 
gets  beyond  the  first  projection,  and  drops  down  -i 
upon  a  second,  and  then  upon  a  third ;  it  thus 
forms  the  succession  of  steps  resulting  from  the 
rapid  advance  of  the  ridge  of  ice  from  which  the  cascade  descends. 

A  comparison  of  the  expex-iments  —  alas!  too  few — which  have  been 
made  up  to  the  present  time  with  regard  to  the  speed  of  various  glaciers 
warrants  us  also  in  thinking  that  the  advance  of  the  current  is  acceler- 
ated in  proportion  to  the  declivity  of  the  slope ;  only,  as  M.  Desor  points 
out,  the  volume  of  the  matter  in  motion  being  by  far  the  principal  ele- 
*  Tyndall,  Glaciers  of  the  Alps. 


Fig.  48.  Cascade  of  Glacier. 


RATE  OF  MOTION  OF  GLACIERS. 


181 


ment  in  the  increase  of  speed  of  the  whole  mass,  the  result  is  that  small 
glaciers  at  a  very  steep  slope  descend  more  slowly  than  larger  ice-rivers 
on  a  slight  declivity. 

Thus  the  advance  of  a  glacier  presents  very  considerable  differences 
in  the  rate  of  progress,  according  to  the  importance  of  the  total  mass  in 
width  and  depth,  its  proximity  either  to  the  edges  or  the  bottom,  the 
winding  of  the  sides,  the  degree  of  slope,  the  expansions  and  contractions 
of  its  bed  of  rocks,  the  state  of  the  temperature,  and  the  various  seasons 
of  the  year.  It  is,  therefore,  impossible  to  estimate  the  mean  rate  of 
speed  of  a  river  of  ice  by  taking  as  our  basis  a  series  of  isolated  observa- 
tions; we  must,  on  the  contrary,  study  the  movement  of  the  ice  in  every 
part  of  its  bed,  take  account  of  every  cause  of  acceleration  and  delay,  and, 
if  we  may  so  speak,  gauge  the  glacier  as  we  should  gauge  a  river  of  run- 
ning water. 

The  movement  of  the  ice,  like  that  of  rivers,  takes  place  over  slopes  of 


(5 


8 

d 

o 

o 

% 

a 

■l 

s 

-1 

^ 

u 

r-i 

Fig.  49.  Slope  of  the  Mer-dc-Glace. 

the  most  varied  character.  The  Mer-de-Glace,  at  Chamounix,  is  inclined 
on  the  average  5  or  6  degrees,  but  at  many  points  in  its  course  it  presents 
a  much  more  considerable  declivity.  Some  glaciers,  half  suspended  on 
the  mountain  sides,  have  an  inclination  of  25, 30,  and  even  50  degrees,  and 
yet  it  is  but  seldom  that  the  masses  lying  on  these  formidable  slopes  take 
to  sliding  on  their  bases  so  as  to  fall  down  like  avalanches  into  the  val- 
ley beneath.*  They  descend  gradually  and  slowly,  like  other  glaciers 
which  are  almost  horizontal  in  appearance,  and  nm  down  gorges  the 
slope  of  which  does  not  attain  to  3  degrees.  The  immense  glacier  of 
Aletsch  is  inclined  only  4  degrees ;  those  of  the  (Etzthal,  on  the  average, 
5  or  6  degrees ;  those  of  Monte  Rosa  and  the  northern  sides  of  the  Fin- 
steraarhorn  group  are  much  more  sloping,  and  incline  10, 15,  and  20  de- 
grees, or,  as  the  upper  glacier  of  Grindelwald,  as  much  as  27  degrees. 
*  De  Charpenrier,  Essaisur  /«  Glaciers. 


182 


'THE  EAMTM. 


CHAPTER  XXXn. 

MARGINAL,  TRANSVERSAL,  AND    LONGITUDINAL    CREVASSES. — SERACS. MOU- 

LINS. — BRIDGES  OF  SNOW. — VEINS  OP  FRESH  ICE. — SURFACE-STREAMS  ON 
GLACIERS. — GOUILLES. — LAKES  AND  INUNDATIONS. — DISCHARGING  CHAN- 
NELS. 

The  whole  mass  of  the  glacier  does  not  advance  in  a  perfectly  continu- 
ous way  as  a  stream  of  water  would  do ;  the  layers  of  ice  could  not  fol- 
low all  the  windings  of  the  gorge  and  adapt  themselves  to  all  the  ine- 
qualities of  the  bottom  without  some  extent  of  fracture.  Thus  fissures,  or 
crevasses^  are  produced  in  the  thickness  of  the  apparently  motionless  riv- 
er, and  sometimes  give  to  the  latter  a  most  uneven  surface. 

Most  of  the  crevasses  in  a  glacier  are  found  near  the  sides,  and  princi- 
pally at  the  convexity  of  the  bends,  on  account  of  the  inequality  of  ten- 
sion to  which  the  layers  of  moving  ice  are  liable  at  these  spots.  The  lay- 
ers which  ai-e  the  closest  to  the  bank  are  retarded  by  the  friction  of  the 


Fig.  50.  Marginal  Crevasses  in  a  Glacier. 

rocks,  while  farther  into  the  stream  the  rapidity  of  the  current  of  ice  in- 
creases with  its  distance  from  the  edge.  This  diflference  in  the  rate  of 
speed  results  in  a  greater  tension  of  the  mass  in  the  direction  of  the  move- 
ment, and  in  consequence  the  ice  on  the  edge  has  to  resist  a  tractile  force, 
acting,  as  MM.  Sonklar  and  Hopkins  have  proved,  in  a  line  inclined  45  de- 
grees to  the  bank.  Finally,  the  ice  gives  way  to  the  power  which  draws 
it ;  it  is  rent  open ;  and,  as  the  laws  of  mechanics  dictate,  the  marginal 
crevasses  are  produced  perpendicularly  to  the  force  of  traction.  The  prin- 
cipal force  of  the  movement  being  exerted  in  the  direction  of  a  line  tend- 
ing up  stream  at  an  angle  of  45  degrees  to  the  bank,  the  fissures  in  general 
form  at  a  similar  angle  to  the  bank,  and  also  tend  up  stream ;  they  are 


CREVASSES  m  OLACIERS. 


183 


consequently  transverse  to  the  course  of  the  current ;  therefore,  at  first 
sight  of  these  clefts,  we  should  be  inclined  to  say  that  the  glacier  advanced 
with  more  rapidity  near  its  edges;  indeed  almost  all  the  first  observers 
were  deceived  on  this  point. 

The  marginal  crevasses,  however,  do  not  retain  their  early  inclination  of 
45  degrees  to  the  bank  of  the  glacier,  the  motion  of  the  current  being  more 
rapid  toward  the  centre  than  near  the  edges ;  the.  fissure  turns  round 
slowly,  like  the  spoke  of  a  wheel,  and  becomes  less  and  less  obliquely 
sloped  toward  the  bank ;  sooner  or  later  it  becomes  perpendicular  to  it, 
and  then  inclines  gradually  in  the  direction  of  the  descent,  describing  a 
more  and  more  acute  angle.  But  while  this  first  crevasse  is  thus  bend- 
ing round  in  a  down-stream  direction,  first  one  and  then  another  marginal 
cleft  may  be  produced  in  the  ice,  subjected  as  it  is  to  the  tractile  force  of 
the  moving  mass ;  and  these  planes  of  rupture  are  at  first  likewise  inclined 
at  an  angle  of  45  degrees  in  an  up-stream  direction,  and  afterward  bend 


^^^>^.s 


Fig.  61.  Intersecting  Crevasses. 


round  in  the  direction  of  the  current.  This  sometimes  results  in  an  inter- 
section of  cracks,  which  transform  the  lateral  portions  of  the  glacier  into 
a  perfect  labyrinth  of  crevasses,  in  which  it  becomes  difficult  to  recognize 
the  regular  order  of  the  successive  phenomena.* 

The  crevasses  which  are  formed  from  bank  to  bank  across  the  field  of 
the  glacier  are  caused  principally  by  the  inequalities  of  its  bed.  In 
places  where  the  declivity  becomes  more  abrupt,  the  ice,  being  unable  to 
accommodate  itself  to  this  fresh  slope,  cracks  right  across,  and  by  a  series 
of  fissures  spreads  out  its  surface  to  form  an  inclination  similar  to  that 
of  the  bed  which  it  covers ;  the  clefts,  it  must  be  understood,  are  all  the 
more  numerous  and  wider  as  the  fall  is  more  sudden. 

Below  rapids  and  cataracts,  rivers  spread  out  into  large  and  smooth 
sheets  of  water ;  a  similar  phenomenon  takes  place  in  glaciers  below  any 
very  steep  slopes.  When  they  reach  these  more  level  beds,  the  masses 
which  have  been  separated  by  the  fissures  again  come  close  together,  and 

*  W.  Huber,  Lea  Glaciers. 


18-1 


THE  EAETH. 


pressing  one  against  the  other,  resume  the  uniformity  of  surface.  If  a 
second  sudden  fall  of  the  bed  gives  a  more  rapid  movement  to  the  river 
of  ice,  it  will  a  second  time  descend  in  a  cascade  of  crevasses^  which  will 
become  obliterated  on  the  mass  reaching  some  less  important  declivity. 


Fig.  52.  Transverse  Cievasse?,  seen  in  Profile. 

The  lower  glacier  of  Grindelwald  presents  a  striking  instance  (first  point- 
ed out  by  Tyndall)  of  this  succession  of  crevasses  and  level  fields  of  ice. 
From  the  tops  of  a  headland  a  clear  idea  may  be  formed  of  the  general 
aspect  of  the  glacier,  and  of  its  alternately  dislocated  and  compressed 
masses.  The  kind  of  semicircular  curve  which  the  transversal  crevasse 
produces  by  uniting  with  the  marginal  fissures  very  often  deceives  the 
sight,  and  would  lead  us  to  believe  that  the  force  of  the  current  was  more 
especially  exerted  at  the  edges,  if  reason  and  experience  did  not  teach  us 
precisely  the  contrary.  It  must  also  be  added  that  these  cross  crevasses 
are  generally  slightly  curved  in  the  direction  of  the  motion. 

In  a  similar  way  to  the  transversal  clefts,  those  which  extend  in  a  lon- 
gitudinal direction  are  likewise  owing  to  the  direction  of  the  bed.     In 


Fig.  5^  Transverse  Crevasses,  seen  in  Plan. 

every  part  of  the  bed  of  the  stream  where  the  longitudinal  risings,  similar 
to  the  shallows  of  a  river,  force  the  ice  to  bend  over  laterally  both  right 
and  left,  the  latter  must  form  parallel  crevasses^  and  these  fissures  can  not 


CREVASSES  IN  OLACJERS. 


185 


close  up  until  they  have  descended  below  the  obstacle.  Added  to  this, 
there  are  often  abrupt  rises  and  falls  in  the  bed  which  are  so  constituted 
as  to  cause  the  simultaneous  rupture  of  the  ice  in  both  a  longitudinal 
and  transvei-se  direction,  and,  consequently,  the  field  of  ice  is  traversed 
by  crevasses  which  are  semicircular  or  bent  round  in  various  directions. 
In  this  way  the  appearance  of  the  surface  often  reveals  the  irregularities 
of  the  bed. 

Lastly,  glaciers  also  exhibit  radiated  crevasses,  especially  at  their  ex- 
tremities, when  the  base  extends  widely  into  the  lower  gorges.  The 
pressure  of  the  masses  descending  from  the  mountain  heights  compels  the 


Fig.  54  Longitadtnal  Crevasses,  seen  in  Plan. 

ice  down  below  to  spread  out  laterally,  and,  in  consequence,  over  the  wnole 
slope  of  the  glacier  there  is  a  formation  of  radiating  crevasses,  sometimes 
exhibiting  the  regular  arrangement  of  the  ribs  of  a  fan.  According  to 
various  slopes  and  the  inequalities  in  its  bed,  the  ice  presents  the  very 
greatest  diversity  in  its  lines  of  fracture.  These  clefts  form  a  perfect  lab- 
yrinth on  the  surface  of  all  glaciers  which  possess  numerous  tributaries, 
and  move  along  a  winding  and  occasionally  contracted  bed. 
Any  one  who  happens  to  be  on  a  glacier  at  a  time  when  a  crevasse  is 


w 

Fig.  55.  Longitudinal  Crevasses,  seen  in  Profile. 

developed  can  not  possibly  resist  a  certain  fooling  of  dread.  The  mon- 
strous river  suddenly  takes  to  cracking  and  groaning ;  dull  reports,  caused 
by  sudden  ruptures,  are  every  moment  heard  in  the  interior  of  the  mass ; 
and  a  prolonged  whistling  sound,  like  that  made  by  glass  when  slit  by  a 
diamond,  announces  the  gradual  increase  of  the  cleft.  Nevertheless,  when 
all  the  voices  of  the  glacier  are  hushed,  it  is  sometimes  quite  in  vain  that 
we  seek  for  the  crack,  on  account  of  its  extreme  fineness.  The  crevasse 
widens  very  slowly,  and  it  takes  days,  and  sometimes  even  weeks,  before 


136  THE  EARTH. 

it  becomes  one  of  those  fonnidable  chasms  which  gash  the  surface  of  the 
glacier. 

When  the  crevasses  have  arrived  at  their  full  development,  they  exhibit 
a  most  striking  spectacle.  The  two  bluish  walls  sink  down  into  dark- 
ness which  is  unfathomable  by  the  eye ;  stones,  falling  from  the  surface, 
bound  over  the  projections,  and  awaken  dull  echoes  as  they  are  lost  in  the 
obscurity ;  a  vague  murmur  of  running  water  ascends  from  the  depths ; 
and  sometimes  sharp  gusts  of  cold  and  biting  air  issue  out  from  the  mouth 
of  the  abyss.  While  leaning  over  the  brink  of  the  gaping  chasm  one 
feels  a  kind  of  dread,  as  if  the  noises  and  darkness  of  the  gulf  beneath 
belonged  to  some  new  world,  full  of  mystery  and  horror.  i 


m 

Fig.  58.  Frontal  or  Terminal  Crevasses— after  Tyndall. 

When  the  crevasses  are  numerous,  and  intersect  one  another  in  various 
directions,  it  often  happens  that  masses  which  are  thus  isolated,  and  are 
also  of  a  more  compact  nature,  resist  for  a  longer  period  the  action  of  the 
sun  and  wind.  In  consequence  of  all  these  inequalities,  and,  doubtless, 
also  on  account  of  the  difference  in  pressure  operating  at  the  base,  the  ice, 
in  some  spots,  assumes  the  most  picturesque  and  fantastic  shapes.  Some- 
times these  blocks  resemble  knights  clad  in  their  armor,  sometimes 
strange  animals,  broken  statues,  pointed  clock-turrets,  or  ruined  colon- 
nades. Tourists  ask  with  astonishment  how  it  is  that  nature,  by  nothing 
but  the  slow  operations  of  the  forces  of  gravity  and  pressure,  the  winds, 
and  solar  rays,  is  able  to  carve  out  the  ice  into  groups  so  remarkable 
both  for  their  regularity  and  grotesqueness.  The  tower-shaped  forms 
which  crown  some  of  the  abrupt  falls  of  the  glaciers  have  received  from 
the  Swiss  mountaineers  the  name  of  shacs/  a  term  which  reminds  dhe  of 
the  s^rets — cheeses  which  split  up  into  small  cubical  pieces. 

In  the  lower  portion  of  the  glacier  surface  the  walls  and  pillars,  which 
are  divided  from  one  another  by  fissures,  seldom  show  perpendicular  sides. 
Their  faces  which  are  turned  toward  the  south  become  wasted  and  worn 
away,  and  thus  assume  the  appearance  of  enormous  congealed  waves. 
When  the  great  river  has  this  furrowed  surface,  it  really  becomes  a  "  sea 
of  ice."  Owing  to  the  more  rapid  motion  of  the  upper  layers,  it  general- 
ly happens  that  the  ice-waves  present  their  steepest  face  in  a  downward 


FEATURES  IN  GLACIERS. 


187 


direction,  and  are  less  abrupt  looking  upward ;  when  this  latter  side  is 
also  that  which  fronts  the  south,  it  ultimately  becomes  a  more  or  less 
inclined  slope. 

In  some  places  the  fields  of  ice  are  also  hollowed  out  into  perpendicular 
wells,  known  under  the  name  of  moulins  (mills),  on  account  of  the  roar- 
ing noise  of  the  water  which  is  ingulfed  in  them.  The  formation  of  these 
abysses  may  be  very  simply  explained.  The  drops  of  water  melting  on 
the  surface  combine  into  slender  rivulets,  which  form  tributaries  of  a 
more  considerable  stream,  which  winds  along  its  bed  of  ice.  When  this 
surface-stream  finds  in  its  path  some  gaping  crevasse^  it  sinks  into  it,  and 
immediately  disappears  in  the  depths  below;  but  it  often  meets  with 
some  crack  crossing  the  field  of  ice  which  is  almost  invisible.  The  water 
makes  its  way  into  this  crack  like  a.blade  of  steel,  and,  gradually  widen- 
ing it,  is  swallowed  up  between  the  separated  sides  of  the  crevice.  Soon 
the  incessant  labor  of  the  water  succeeds  in  hollowing  out  a  complete 
well,  which  sinks  down  to  the  stream  hidden  under  the  glacier.  This 
inoulin  shifts  its  position  with  the  whole  mass  surrounding  it ;  but  at 
the  spot  where  it  was  formed  a  new  cleft  is  produced  in  the  glacier  by 
the  same  causes  as  the  first,  and  the  little  stream  gradually  bores  out  in 
it  a  second  deep  hole.  Thus,  on  the  same  line,  several  circular  wells  are 
hollowed  out,  the  most  elevated  of  wBich  is  the  funnel  of  a  cataract, 
while  each  of  the  others  has,  in  its  turn,  been  deserted  by  the  water  that 


Pig.  67.  Superficial  Torrents  of  a  Glacier— after  TyndalL 

formed  it.  MbiUins,  like  crevasses,  are  sometimes  made  use  of  by  ob- 
servers who  wish  to  measure  approximately  the  thickness  of  a  glacier, 
either  by  noticing  the  duration  of  the  fall  of  a  stone,  or  by  employing  a 
sounding-line.  In  this  way  the  thickness  of  some  of  the  Alpine  glaciers 
has  been  estimated  at  800,  1000,  and  even  1650  feet. 

In  winter  both  moulins  and  crevasses  are  either  altogether  or  in  part 
filled  with  snow,  which  makes  its  way  into  the  interstices  of  the  ice,  and 
moulds  itself  to  fit  them  just  like  lava  flowing  into  the  clefts  of  a  rock. 
When  the  mass  of  snow  does  not  descend  right  down  into  the  depths  of 


188 


THE  EARTH. 


the  crevasse,  and  only  manages  to  unite  the  two  edges  of  it,  it  forms  over 
the  chasm  a  kind  of  bridge,  which  a  mere  shaking  of  the  glacier  will 
sometimes  suffice  to  hurl  down.  These  unsupported  beds  of  snow  consti- 
tute the  greatest  danger  for  travelers  who  venture  on  to  glaciers.  There 
is  no  visible  indication  to  point  out  the  vast  gulf  below,  which  descends 
perhaps  to  a  depth  of  hundreds  of  yards.  The  field  of  snow  is  level,  and 
seems  to  invite  one  to  walk  over  it ;  but  if  an  incautious  traveler  sets  his 
foot  upon  the  snow  spread  over  the  chasm  before  he  has  carefully  sound- 
ed it,  the  mass  may  suddenly  give  way,  carrying  with  it  the  unfortunate 
individual  whom  it  has  failed  to  support.  The  greater  part  of  the  acci- 
dents which  happen  every  year  upon  the  mountains  are  owing  to  the  fall 
of  these  snow-bridges  across  the  chasms  of  the  glaciers. 

Generally  the  snow  in  the  crevasses  is  the  first  to  melt  and  fall  down  in 
the  hot  season,  on  account  of  its  position  being  exactly  in  the  spot  where 
the  surface-water  chiefly  flows ;  but  it  often  happens  that,  in  consequence 


Fig.  58.  Chasms  In  a  Glacier  filled  with  Snow— after  TyndalL 

of  the  motion  of  the  glacier,  some  of  these  chasms  filled  with  snow  do  not 
fall  in  the  way  of  any  of  the  rivulets  running  over  the  surface.  In  this 
case  the  snow  gradually  hardens,  and  ultimately  becomes  changed  into 
ice,  under  the  pressure  of  the  layers  surrounding  it.  This  recently-formed 
ice  is  at  first  distinguished  by  its  whitish  shade,  its  granular  texture, 
and  a  great  abundance  of  air-bubbles.  Thanks  to  its  color,  it  resists  the 
melting  influences  longer  than  the  surface  round  it,  and  may  sometimes 
be  distinguisljpd  from  a  considerable  distance  by  a  kind  of  cone  which 
shows  itself  above  the  field  of  ice.  It  also  sometimes  happens  that  simi- 
lar white  veins  of  transformed  snow  fill  up  all  the  windings  of  the  beds 
of  the  temporary  streams  which  are  hollowed  out  in  the  thickness  of  the 
glaciers.  In  the  tributaries  of  the  Mer-de-Glace,  Tyndall  remarked  sev- 
eral of  these  moulds  of  former  streams. 

Lakes,  as  well  as  miniature  rivers,  fill  up  the  depressions  in  some  gla- 
ciers. Sometimes  they  are  mere  ponds,  or  gouilles,  formed  in  some  unfin- 
ished crevasse;  in  other  cases  they  are  like  wells,  and  sink  down  to  the 
rocks  in  the  bed  of  the  glacier.    In  some  localities,  the  surface-water, 


GLACIERS  AS  BARRLEMS.  189 

finding  no  outlet  to  the  valley  beneath  through  the  solid  mass  which 
covers  the  ground,  collects  in  a  hollow  between  the  field  of  ice  and  the 
sides  of  the  rock.  Cliffs  of  a  deep  blue  tinge,  with  snow-capped  summits, 
border  the  lake-like  sheet  of  water,  which  is  still  bluer  than  the  ice  itself 
Sometimes  blocks,  separated  by  fissures  from  the  masses  above,  break 
away  with  a  crash,  and,  as  they  plunge  into  the  water,  raise  high  waves, 
which  spread  rapidly  across  the  basin,  and  breaking  on  the  opposite  cliff- 
like shore,  describe  on  the  surface  of  the  lake  a  graceful  net-work  of  in- 
terwoven ripples.  Little  islets  of  still  unmelted  ice  float  here  and  there 
under  the  impulse  of  the  wind,  which  blows  hard  through  the  mountain 
gorges.  There  are  few  sights  more  charming  among  the  lofty  mountains 
than  these  little  lakes  surrounded  by  snow,  like  sapphires  set  in  silver. 

The  greater  part  of  these  glacier  lakes  are  formed  by  the  waters  of  a 
lateral  gorge  which  is  penned  up  by  a  natural  barrier  of  ice.  This  water, 
proceeding  from  the  upper  snows,  or  from  secondary  glaciers,  which  do 
not  descend  to  any  great  distance  from  the  summit,  finds  its  passage  ob- 
structed by  the  body  of  the  principal  glacier  pushing  on  its  way  toward 
the  plain,  and,  thus  arrested  in  its  course,  forms  elongated  lakes,  the  lower 
extremity  of  which  abuts  on  the  barrier  of  ice.  Some  of  these  lakes  are 
of  a  permanent  character,  and  some  merely  temporary.  The  former,  oc- 
cupying deep  depressions  hollowed  out*  in  the  rock  itself,  can  not  possibly 
flow  down  into  the  valley;  the  latter,  being  only  kept  back  by  ramparts 
of  ice,  sometimes  melt,  and  sometimes  throw  down  the  obstacle  which 
opposes  their  outlet.  As  soon  as  the  icy  wall  yields  to  the  pressure  of 
the  water,  the  latter  pours  out  in  a^  sudden  and  mighty  rush,  the  lake  is 
changed  into  a  torrent,  or  plunges  in  furious  cataracts  down  into  the 
gorges  beneath,  and  in  a  ie\f  hours  discharges  the  liquid  mass  which  had 
been  accumulating  during  a  long  period  of  years,  or  perhaps  centuries. 

The  history  of  Alpine  inundations  is  full  of  incidents  of  this  kind. 
Thus  it  was  that  the  lake  of  Rofen,  which  had  been  forming  for  fourteen 
days  by  the  encroachment  of  the  glacier  of  Vernagt,  in  the  (Etzthal,  sud- 
denly opened  for  itself  a  passage.  Within  an  hour's  time  its  basin  was 
completely  emptied,  the  valley  of  Sulden  was  devastated  by  blocks  of 
rock  and  sand,  and  the  Inn  itself,  swelled  by  the  sudden  flood,  laid  waste 
its  banks  as  far  as  its  confluence  with  the  Danube,  The  temporary  tor- 
rent which  the  inundation  threw  into  the  Inn  was  not  less  than  three 
millions  of  cubic  yards  of  water,  at  the  rate  of  953  yards  a  second.  This, 
however,  is  a  trifling  matter  compared  with  the  mass  of  water  that  must 
have  rolled  down  if  the  lake  of  Rofen  had  found  no  means  of  escape  for 
several  years. 

The  lower  glacier  of  Gietroz,  which  flows,  at  a  height  of  6036  feet,  into 
the  valley  of  Bagnes,  not  far  from  the  Monte  Rosa  group,  had  in  the 
same  way  several  times  dammed  up  the  passage  of  the  stream  of  the 
Dranse,  a  tributary  of  the  Rhone ;  but  in  a  general  way  the  barrier  of  ice 
melted  at  the  beginning  of  spring,  and  no  catastrophe  had  to  be  deplored. 
In  1818  the  case  was  different;  the  mass  of  ice  descending  from  the  up- 


190 


THE  EARTH. 


per  neves  was  so  considerable  that  tlie  Dranse,  being  unable  to  flow 
through  it,  was  driven  back,  and  necessarily  changed  into  a  lake  above 
the  obstacle.     At  the  beginning  of  May,  the  dam  of  ice,  which  was  about 


Fig.  59.  The  Glacier  of  Gictroz  in  1818. 

660  feet  in  length  between  the  two  mountains,  was  not  less  than  420  feet 
high,  and  more  than  30,000  feet  in  width  at  its  base.  The  lake,  more 
than  half  a  mile  in  width,  was  incessantly  increasing,  and  its  depth,  which 
in  certain  spots  reached  260  feet,  augmented,  on  the  average,  three  feet  a 
day.  Its  contents  might  be  estimated  at  more  than  six  millions  and  a 
half  of  cubic  yards.  The  danger  was  a  terrible  one  to  the  inhabitants 
of  the  valley  below.  Under  the  direction  of  Venetz,  the  engineer,  they 
set  to  work  to  dig  a  draining  channel  across  the  rampart  of  ice,  and  suc- 
ceeded, in  fact,  in  gradually  lowering  the  level  of  the  water  of  the  lake. 
On  the  16th  of  June,  at  four  o'clock  in  the  afternoon,  the  barrier  gave 
way;  the  pent-up  water,  driving  before  it  both  ice  and  rocks,  suddenly 
sprang  into  the  valley  with  such  rapidity  that  in  twenty  minutes  the 
whole  basin  was  empty.  This  formidable  cataract  swept  away  woods 
and  chdlets,  and  laying  bare  the  rocks,  and  carrying  away  the  very  mead- 
ows, emptied  itself  into  the  plain  like  a  mingled  avalanche  of  water,  trees, 
and  debris^  300  feet  in  height,  and  preceded  by  a  black  and  thick  vapor, 
like  the  smoke  of  a  conflagration.     The  havoc  was  very  considerable,  not 


DRAINING   CHANNELS.  igX 

only  in  the  valley  of  the  Dranse,  but  also  on  the  banks  of  the  Rhone.  In 
order  to  avoid  the  return  of  a  similar  disaster,  the  draining  channel  of 
the  Dranse  was  cut  out  afresh  every  year  beneath  the  glacier.  This 
operation  gave  an  opportunity  of  ascertaining  the  adhesion  of  the  ice  to 
the  bed  over  which  it  flows,*  even  at  an  altitude  comparatively  not  very 
considerable.  The  lake  of  Moril,  which  is  penned  up  by  the  enormous 
barrier  of  the  glacier  of  Aletsch,f  also  communicates  with  the  valley  of 
the  Rhone  by  a  draining  channel  which  carries  off"  the  overflow  of  its 
waters. 

*  De  Charpentier,  Essai  sur  Ics  Glaciers.  t  Vide  p.  207. 


192  THE  EAMTH. 


CHAPTER  XXXIII. 

DEBRIS  EYING  ON  THE  SURFACE  OF  THE  GLACIER. — HOLES  IN  THE  SURFACE. 
GLACIAL  TABLES. MORAINES  ;  LATERAL,  MEDIAL,  AND  FRONTAL. — RIB- 
BONS OF  MUD. — MEASUREMENT   OF  THE  SPEED  OF  GLACIERS. — ABLATION. 

SUB-GLACIARY     STREAMS. TERMINAL     ARCHES. CONTRAST     BETAVEEN 

THE   GLACIER   ICE   AND  THE   SURROUNDING  VEGETATION. 

Like  all  other  rivers,  the  glacier  beai's  along  with  it  a  certain  quantity 
of  alluvium,  which  it  ultimately  deposits  at  the  end  of  its  course,  after  a 
lapse  of  time  which  varies  in  length.  The  moving  surface  of  the  ice  re- 
ceives all  the  debris  which  has  been  detached  from  the  bare  cliffs  by  the 
action  of  thaw,  rain,  wind,  or  other  meteoric  agents,  all  the  avalanches  of 
stones  which  come  down  with  the  snow  from  the  ravines  above,  all  the 
fragments  of  those  immense  ruins  which  tower  up  in  the  form  of  needle- 
shaped  peaks  or  jagged  ridges.  Glaciers  which  are  shut  in  between 
schistose  mountains,  the  sides  of  which  easily  crumble  away,  are  often 
quite  black  with  debris ;  others,  on  the  contrary,  which  are  commanded 
by  more  compact  rocks,  or  long,  snow-clad  slopes,  retain  partially  the 
whiteness  of  their  surface ;  but  all  carry  with  them  along  one  or  both  of 
their  banks  a  certain  quantity  of  rocks  and  stones  belonging  to  all  the 
geological  formations  of  the  basin.  Borne  along  by  the  ice,  this  rocky 
rubbish  commences  but  slowly  its  journey  toward  the  sea,  where  it  ar- 
rives, sooner  er  later,  in  the  form  of  sand  or  mud. 

Some  parts  of  the  dehris  which  fall  from  the  cliffs  into  the  bed  of  the 
glacier  gradually  make  a  hole  for  themselves  and  disappear  in  the  depth 
below  ;  others,  on  the  contrary,  seem  to  rise  in  consequence  of  the  gradual 
sinking  of  the  surrounding  surface.  In  fact,  if  a  small  pebble  of  a  dark 
color  lies  during  the  day  on  a  bed  of  ice,  it  will  rapidly  absorb  the  solar 
rays,  and,  melting  the  particles  on  which  it  rests,  will  descend  slowly  into 
the  little  well  which  it  bores  by  the  action  of  its  own  heat ;  sometimes  the 
disappearance  of  all  the  debris  gives  the  surface  of  the  glacier  an  appear- 
ance like  an  immense  sieve.  The  result  is,  however,  quite  different  when, 
instead  of  isolated  stones,  great  masses  of  rock  roll  down  upon  the  glacier 
in  a  body.  These  large  heaps  are,  it  is  true,  warmed  on  their  surface  by 
the  solar  rays,  but  at  the  same  time  they  protect  the  space  of  ice  that  they 
cover  against  the  heat.  Therefore,  all  round  them,  the  surface-layers  of 
the  glacier  gradually  melt  and  evaporate,  Avhile  these  lumps  retain  their 
original  height,  and  seem  even  to  increase,  like  volcanic  cones.  Finally, 
however,  the  base  of  the  cone  of  ice  which  bears  up  these  heaps  of  rock 
gradually  melts  away,  the  debris  slide  down  on  the  slope  which  has  become 
too  steep  to  keep  them  up,  and  soon  after  the  hillock  sinks  and  disappears. 


GLACIER  TABLES. 


193 


A  phenomenon  of  the  same  nature  takes  place  when  a  large  block  of 
stone — such  as  a  slab  of  schist  or  granite — covers  the  ice  and  shelters  it 
from  the  rays  of  the  sun.  The  surrounding  surface  slowly  sinks,  leaving 
underneath  the  slab  of  stone  a  pillar  like  a  marble  column  crowned  with 
a  heavy  capital.  However,  on  the  glaciers  of  the  Alps  and  other  mount- 
ains of  the  temperate  zone,  these  slabs  of  stone  never  lie  horizontally  on 
their  pedestals ;  being  shone  upon  obliquely  by  the  southern  sun,  they  re- 
ceive the  most  heat  from  this  quarter,  and  they  warm  the  corresponding 
side  of  the  pillar  supporting  them.  Simultaneously  the  solar  rays  melt 
away  some  of  the  lower  portion  of  the  pillar  of  ice,  so  that  the  slab  grad- 
ually bends  over  toward  the  south.    As  a  matter  of  theory,  as  Tyndall 


Fig.  60.  Glacier-table ;  after  TyndalL 

says,*  these  slabs  ought  to  turn,  like  a  kind  of  sun-dial,  simultaneously  with 
the  sun,  and  thus  mark  every  hour  of  the  day ;  but  this  daily  rotation  is 
too  slight  to  be  perceptible,  and  the  general  result  is  all  that  can  be  ascer- 
tained— that  is,  the  inclination  of  the  stones  toward  the  south. '  Ultimate- 
ly, the  inclination  becomes  so  rapid  that  the  stone  slab  falls  from  the  top 
of  its  column,  and  immediately  after  begins  to  form  a  second  ;  thus  pillar 
follows  pillar  under  the  rocky  masses  borne  along  by  the  ice.  Some  of 
these  natural  dolmens  have  been  noticed  having  an  area  of  twenty-four  to 
thirty  square  yards.  Among  the  variously-shaped  rocks  which  are  car- 
ried along  by  the  glacier,  some  attain  a  bulk  of  thousands  of  cubic  yards. 
The  rock  called  Blaustein,  which  we  now  see  in  the  valley  of  Saas,  is  a 
mass  of  serpentine  more  than  10,000  cubic  yards  in  bulk,  which,  in  1740, 
was  still  upon  the  glacier  of  Mattmark.f 
It  is  perfectly  natural  that  at  first  all  the  rocks  and  debris  which  have 
•  Glaciers  of  the  Alps.  t  De  Charpentier,  Essai  sur  les  Glaciers. 

N 


194 


TKE  EARTH. 


rolled  down  should  lie  at  the  foot  of  the  high  walls  of  rock  which  over- 
look the  glacier.  These  heaps  constitute  the  lateral  moraines,  or  ranges 
of  stones,  running  in  a  line  on  each  side  of  the  bed  of  ice  like  roughly- 
made  ramparts,  and  participating  in  the  movement  of  the  frozen  river. 
Sometimes,  however,  these  broken  rocks  are  buried  in  the  hollows  which 


01.  Lateral  2*Iorames. 


open  either  at  the  base  of  the  mountain,  or  at  a  little  distance  from  it  in 
the  heart  of  the  glacier  itself  The  moraine  is  then  concealed  in  the 
midst  of  the  glacier,  but,  embraced  as  it  is  by  the  whole  moving  mass  of 
ice,  it  does  not  fail  to  descend  toward  the  valley ;  and  often,  when  the  up- 
per layers  are  melted,  it  again  makes  its  appearance  above  the  surface 
and  overtops  the  level  of  the  glacier.  Some  of  these  lateral  moraines  rise 
to  a  height  of  70  or  80  feet  above  the  current.  On  the  Murzoll,  in  the 
Austrian  Alps,  there  are  several  which  are  more  than  100  feet  high. 

Below  the  confluence  of  two  glaciers,  the  moraines  which  skirt  both 
sides  of  the  base  of  the  central  promontory  unite  like  the  solid  waves 
which  bear  them  along,  and  thus  form  in  the  middle  of  the  river  of  ice  a 
third  moraine,  running  parallel  to  those  on  the  edges.  If  a  third  tribu- 
tary glacier  runs  into  the  principal  current,  a  second  medial  moraine  is 
formed  on  the  glacier,  parallel  to  the  first ;  finally,  however  great  may  be 
the  number  of  the  tributaries,  each  of  them  will  unite  one  of  its  lateral 
moraines  to  that  of  the  principal  glacier,  so  as  to  form  another  medial 
ridge  of  debris.  By  examining  the  surface  of  a  glacier  of  regular  devel- 
opment, such  as  the  Mer-de-Glace,  or  the  glaciers  of  Geisberg  or  Roth- 
moos,  the  number  of  its  tributaries  may  be  reckoned  by  the  number  of 
walls  of  debris  which  extend  along  the  line  of  its  current. 

A  number  of  these  medial  moraines  disappear  at  their  very  source  in 
the  depths  of  the  crevasses.  They  remain  buried  in  the  heart  of  the 
glacier  until  the  layer  above  them  is  entirely  melted,  and  then,  after  hav- 
ing traversed  a  greater  or  less  distance,  they  reappear  on  the  surface  as  if 
they  had  been  upheaved  by  some  great  eruptive  force.  It  is  curious  to 
notice  how,  at  a  distance  of  many  hundreds  of  yards,  or  even  some  miles, 
the  enormous  alluvium  of  rocks  retains  its  original  direction.  The  rivers 
of  ice  poured  out  by  the  tributary  into  the  common  bed  flow  on  side  by 
side  without  mingling  their  masses ;  in  the  same  way  rivers,  the  waters 
of  which  differ  in  color,  like  the  Missouri  and  the  Mississippi,  roll  on  to- 
gether in  the  same  channel  for  a  long  time  without  intermixing  their 


GLACIERS  OF  CEISBERC    AND    ROTHMOOS 


Pl.XU 


I  Hohrr  First 


*W  MW 


litig^  V  ErK«rilir  Duguiyltouin  lirawn  bt  AVuilltmin    after  SonMar 

HAPJ=ER  &.  3R0THERS    ^iLW  VCiRl-L 


TERMINAL  MORAINES. 


195 


waves.  The  steep  faces  of  the  side  glaciers  sometimes  exhibit  most  clear- 
ly the  vertical  line  which  separates  the  contiguous  masses  of  two  tribu- 
taries which  have  flowed  in  above. 

After  a  long  course  of  years,  or  even  centuries,  the  masses  of  the  lateral 
and  medial  moraines  reach  the  lower  extremity  of  the  glacier,  and  fall 
one  over  the  other  down  the  slope  of  the  valley.  During  a  succession 
of  ages,  the  stones  which  are  too  heavy  to  be  carried  away  by  the  action 
of  water  are  collected  together  in  enormous  heaps  below  the  river  of  ice. 


Figs.  <}3, 63, 64, 65.  Frontal  or  Terminal  Moraines. 

These  heaps  constitute  the  great  frontal  moraines  which  obstruct  the  ap- 
proach to  so  many  glaciers,  as  these  formidable  slopes  are  sometimes 
hundreds  of  feet  in  height.  These  moraines^  consisting  of  a  vast  rough 
alluvium,  pushed  on  by  the  ice,  make  their  way  for  a  greater  or  less  dis- 
tance into  the  valleys,  according  to  the  pressure  of  the  masses  above. 
When  the  force  of  the  latter  increases,  the  accumulation  of  blocks  moves 
onward,  and,  in  its  irresistible  progress,  overwhelms  plains,  rocks,  and  tor- 
rents. On  the  other  hand,  when  the  glacier  recedes,  the  enormous  barrier 
in  front  of  it  remains  isolated,  like  a  rampart  built  up  across  the  valley, 
and,  higher  up,  the  glacier  constructs  another  frontal  moraine  with  the 


aiihA 


RSE^ 


Fig.  66.  Profile  of  the  Valley  of  Avoca,  New  Zealand ;  after  Julias  Haast 

debris  it  carries  down  with  it.  In  several  gorges,  especially  in  that  which 
extends  below  the  glacier  of  the  Rhone,  and  likewise  in  the  New  Zealand 
valley  of  Avoca,  six  or  seven  moraines  in  a  line  have  thus  been  abandoned 
by  the  ice,  the  lower  extremity  of  which  has  receded  upward.     But  if  the 


196 


THE  EARTH. 


frozen  river  recommences  its  gradual  advance,  then  these  heaps  will  be 
added  to  the  other  debris,  and  all  these  old  moraines  will  unite  in  one  gi- 
gantic moving  rampart.  In  a  similar  manner,  glaciers  which  have  dimin- 
ished in  size,  and  have  stranded  their  lateral  moraines  on  the  adjacent 
slopes,  may,  when  they  again  increase,  once  more  pick  up  these  debris : 
like  a  flooded  river  carrymg  off  the  drifted  wood  left  upon  its  banks,  the 
river  of  ice  may  impel  the  mass  of  blocks  a  second  stage  toward  the  sea. 

In  addition  to  these  various  kinds  of  lateral  and  medial  Tnoraines,  the 
surface  of  some  glaciers  exhibits  concentric  bands  of  mud  and  rubbish,  ar- 
ranged, in  some  cases,  with  the  greatest  regularity.  The  Mer-de-Glace,  in 
the  Mont  Blanc  group,  is  a  remarkable  instance  of  this  singular  distribu- 
tion of  these  layers  of  mud  on  the  glacier  field.  The  first  bands  of  mud 
appear  below  the  great  cataract  of  seracs  which  are  found  between  the 
n^v^  of  the  Col-du-Geant  and  the  glacier  proper.  During  the  heat  of 
summer,  when  the  renewed  activity  of  the  glacier  communicates  a  more 
rapid  impetus  to  all  the  layers  in  motion,  the  fallen  rubbish  accumulates 
in  a  circular  rampart  at  the  base  of  the  escarpment,  and  then,  carried 
away  by  the  current  of  the  river  of  ice,  advances  slowly  in  the  rear  of 
other  ramparts  which  had  fallen  previously.  Mud,  dust,  and  fragments 
of  every  kind  gradually  fill  up  the  furrows  made  between  the  raised  bar- 
riers of  ice ;  the  latter  gradually  melt,  and  ultimately  assume  the  same 


Fig.  67.  RibbonBofMnd,Mer-de-Qlace;  after  Forbes. 


level  as  the  general  surface  of  the  current,  but  the  belts  of  brown  or  red- 
dish mud  still  retain  their  ribbon-like  arrangement,  and,  like  the  concen- 
tric undulations  which  form  in  smooth  water,  present  at  first  an  almost 
perfect  semicircular  curve.  But  at  the  contraction  of  the  ravine  at  Tre- 
laporte,  where  the  whole  river  of  ice  is  compressed  and  is  compelled  to 
pass  through  a  narrow  channel,  the  belts  of  mud  are  drawn  out  toward 
the  centre  on  account  of  the  increased  rapidity  of  the  movement  which 
carries  them  along.  These  zones  of  mud,  the  curves  of  which  are  in  a 
contrary  direction  to  those  of  crevasses,  may,  therefore,  be  looked  upon  as 
regular  floats  indicating  the  direction  and  exact  progress  of  the  current 
of  ice.  Perhaps,  also,  in  each  interval  between  the  ribbon-like  belts  we 
ought  to  see  the  precise  measure  of  the  annual  growth  of  thg  glacier,  and 
the  belts  would  resemble  the  rings  of  wood  which  trees  produce  every 


ANNUAL  MOTION  OF  OLACIES&  I97 

year,  by  which  we  are  enabled  to  calculate  the  age  of  the  trunks.  If  this 
were  the  case,  the  central  part  of  the  Mer-de-Glace  would  entirely  pass 
away  in  about  forty  years,  and  the  average  rate  of  speed  would  be  about 
23^  inches  a  day,  which  agrees,  in  fact,  with  the  actual  measurements 
which  have  been  made  by  various  observers  of  the  advance  of  the 
glacier. 

When  several  generations  of  savants  shall  have  followed  up,  one  after 
the  other,  this  kind  of  investigation,  we  shall  perhaps  learn  the  exact  speed 
at  which  the  stream  of  ice  moves  onward.  This  will  be  effected  by  drop- 
ping into  the  deep  fractures  on  the  highest  point  of  the  glacier  various 
objects,  which  the  mass  will  carry  on  with  it  down  to  the  bottom  of  the 
gorge,  and  will  ultimately  leave  bare  at  its  terminal  moraine.  A  ladder 
which  Saussure  left,  in  1788,  at  the  foot  of  the  Aiguille-Noire,  when  he  as- 
cended Mont  Blanc,  was  found,  in  1832,  at  a  distance  of  4757  yards  below. 
The  ladder  had,  therefore,  descended  during  these  forty-four  years  at  an 
average  annual  speed  of  108  yards,  or  nearly  11  inches  a  day.  A  knap- 
sack which,  in  1836,  fell  into  a  crevasse  of  the  glacier  of  Taldfre,  traveled 
more  rapidly  than  Saussure's  ladder;  it  moved  on  at  the  rate  of  140  yards 
a  year,  or  nearly  14  inches  in  the  twenty-four  hours.  But  all  these  ob- 
servations fail  in  serving  as  exact  measurements  of  the  real  speed  of  the 
mass  of  the  glacier,  for  it  would  be  necessary  to  know  precisely  if  the 
foreign  bodies  which  were  carried  along  lay  in  the  central  part  or  on  the 
edges  of  the  icy  current,  in  its  very  heart  or  in  the  vicinity  of  the  bottom. 
However  this  may  be,  approximate  calculations  lead  to  the  belief  that  the 
snow  that  falls  on  the  Col-du-Geant  takes  about  one  hundred  and  twenty 
years  ere  it  arrives,  changed  into  ice,  at  the  lower  extremity  of  the  Glacier 
des  Bois.* 

Human  remains,  too,  have  unhappily  served  as  means  for  estimating 
the  rate  of  movement  of  the  ice.  In  1861, 1863,  and  1865  the  Glacier  des 
Bossons  has  yielded  up  the  relics  of  three  guides  who  fell,  in  1820,  into  the 
first  crevasse  opening  at  the  foot  of  Mont  Blanc.  These  buried  remains 
had,  therefore,  during  a  period  of  more  than  forty  years,  passed  over  a 
space  of  about  three  miles  and  three  quarters,  descending  at  the  rate  of 
160  to  170  yards  each  year.  In  the  year  1860  a  more  slowly-moving 
glacier  in  the  Austrian  Alps,  which  flows  in  the  Ahrenthal,  threw  out  a 
well-preserved  corpse,  still  clad  in  a  dress  the  ancient  fashion  of  which 
had  been  abandoned  by  the  mountaineers  for  centuries.f 

Each  glacier,  taken  as  a  whole,  may  be  looked  upon  as  forming  tioo  riv- 
ers, one  of  which  takes  years,  or  even  a  century,  in  descending  from  the 
summits  into  the  valley,  having  assumed  the  shape  of  solid  ice  ;  the  other 
flows  down  in  a  few  days,  and  in  the  day-time  assumes  the  appearance 
of  a  stream.  In  summer,  the  phenomenon,  which  has  been  designated  by 
the  name  of  ablation — that  is,  the  surface-melting  of  the  ice — takes  place 
rather  rapidly.     In  the  month  of  August,  on  the  glaciers  of  the  Central 

•  Helmholz,  La  Glace  et  les  Glaciers. 

t  Adamello-Gruppe  ;  Mittheilungen  von  Petermann. 


198  ^^^  EARTH. 

Alps,*  the  thickness  of  ice  melted  averages  from  one  to  \i^  inch  a  day,  and 
during  a  series  of  days  which  are  favorable  to  the  melting  process  the 
layer  of  ice  which  changes  into  water  is  still  more  considerable.  Accord- 
ing to  M.  Desor,  the  mean  ablation  in  a  spot  favorably  situated  in  the 
middle  of  the  Glacier  de  I'Unteraar  rose  to  2f  inches  a  day  during  sev- 
eral months.  On  the  Glacier  du  Gurgl  (CEtzthal),  not  very  far  below  the 
lower  limit  of  the  nev^,  Sonklar  found,  in  the  month  of  August,  five  sur- 
face-rivulets which  together  discharged  15f  cubic  yards  of  water  a  min- 
ute, 45  gallons  a  second ;  and  on  the  great  glaciers  of  the  Swiss  Alps  tem- 
porary water-courses  must  doubtless  be  formed  of  much  greater  impor- 
tance. In  autumn  and  winter  the  amount  of  ablation  is  diminished,  but 
this  phenomenon  rarely  ceases  altogether,  and  in  spots  which  receive  the 
solar  rays,  or  are  touched  by  the  warm  mists  of  the  plain,  small  rills  of 
water  hollow  out  a  bed  for  themselves  in  the  ice  and  among  the  debris  of 
the  moraines.  M.  Desor  has  estimated  the  mean  ablation  on  tha  Swiss 
glaciers  as  amounting  to  10  feet  a  year,  or  0"3176  inch  a  day.f 

The  thawed  water  which  trickles  over  the  surface  of  a  glacier  sinks  into 
the  crevasses  and  the  moulins,  and  makes  its  way  from  fissure  to  fissure 
to  the  deepest  recesses  of  the  gorge,  now  filled  up  by  the  frozen  river. 
Owing  to  its  temperature  being  somewhat  above  freezing-point,  the 
water,  when  •  collected  in  this  hidden  bed,  and  here  and  there  mingled 
with  the  flow  from  springs,  thaws  a  certain  quantity  of  ice  above  its 
course,  and  thus  opens  out  a  free  passage  toward  the  valley.  The  stream 
which  gushes  forth  at  the  base  of  every  glacier  represents,  in  its  annual 
discharge,  the  whole  of  the  snow  which  falls  in  the  gorges  and  on  the  trib- 
utary escarpments.  All  that  has  to  be  deducted  is  the  moisture  which 
has  evaporated,  and  the  water  which  is  lost  in  the  clefts  and  holes  of  the 
mountain. 

Thus  several  of  the  rivers  which  spring  from  glaciers  afford  a  very  con- 
siderable flow  of  water.  The  discharge  of  the  Aar,  as  it  springs  from  the 
ice,  fluctuates  between  5  and  30  cubic  yards  of  water  a  second.J  The 
Rhone,  the  Rhine,  and  the  Arveiron  also  form  considerable  streams  as 
they  issue  from  their  changeable  grottoes.  In  summer,  when  torrents  of 
water  rush  forth  from  the  glacier,  they  bear  with  them  masses  of  debris 
and  excessively  fine  sand  and  mud,  proceedmg  from  the  continual  grind- 
ing of  the  rocks  by  the  under-surface  of  the  glacier.  The  water  holding 
this  matter  in  suspension  is  yellow,  gray,  or  blackish,  according  to  the 
nature  of  the  rocks  over  which  it  flows  in  its  sub-glacial  course.  During 
the  cold  season,  when  it  is  all  frozen  along  its  rocky  bed,  the  stream 
usually  becomes  perfectly  limpid;  nevertheless,  a  certain  number  of 
mountain  streams  are  mentioned,  the  color  of  which  always  resembles 
that  of  the  ice  itself;  the  quantity  of  small  debris  with  which  they  are 
charged  gives  them  a  shade  both  turbid  and  bluish,  as  if  they  were  mixed 
with  milk. 

*  See  Agassiz,  Martins,  and  Sonklar.  t  Excursions  et  Sejows  dam  les  Glaciers. 

\  DoUfuss-Ausset,  Materiaux  pour  servir  a  F Etude  des  Glaciers. 


ICE- CAVERNS  IN  GLACIERS. 


199 


An  arcade  of  vast  proportions  generally  rises  over  the  source.  Some 
of  these  open  out  with  gigantic  and  almost  regular  portals  with  pointed 
arches,  hollowed  out  of  the  ruin-like  cliff  which  terminates  the  glacier. 
But  each  advance  and  each  retreat  of  the  mass  of  ice  results  in  an  altera- 
tion of  the  shape  and  appearance  of  the  grotto  out  of  "which  the  stream 
flows.  Sometimes  the  vault  above  partially  gives  way  under  the  weight 
of  the  upper  strata,  and  large  sloping  layers  become  detached  from  the 
sides  or  from  the  arcTi ;  fissures  and  crevasses^  like  the  clefts  in  cavernous 
rocks,  cut  through  the  walls  of  ice  in  every  direction,  and  every  now  and 
then  blocks  break  away  and  fall  with  a  crash  into  the  torrent.  Visitors, 
therefore,  who  wish  to  admire  closely  the  vault  of  crystal,  and  to  contem- 
plate the  lovely  effects  of  light  which  are  produced  by  the  reflections  of 
sunshine  passing  through  the  transparent  ridges  at  the  edges,  and  falling 
on  the  blue-tinted  walls,  are  not  able  at  all  times  to  venture  without  im- 
prudence into  the  depths  of  the  cavern.     Blocks  of  ice  and  rocks  often 


Sources  of  the  Arveiron. 


obstruct  the  flow  of  the  water,  and  it  is  but  very  rarely  that  these  deep- 
ly-cavemed  water-courses  preserve  much  regularity  of  form  for  any  con- 
siderable time.  Nevertheless,  several  instances  are  mentioned  of  men 
who,  having  fallen  into  the  bed  of  the  stream  through  a  crevasse  in  the 
upper  part  of  the  glacier,  have  been  able  to  find  their  way  again  into  the 
open  air,  by  following  the  course  of  the  water  across  the  scattered  debris 
and  through  the  frightful  dat-kness  of  these  unknown  gulfs.     In  the  very 


200  ■  ^^^  EARTH. 

depth  of  winter,  the  entrance  to  the  terminal  arches  is  sometimes  entirely 
obstructed  by  snow  and  ice ;  the  cold  checks  the  torrent,  and  freezes  it  at 
the  mouth  of  the  glacier.  This  was  the  case  in  January,  1854,  when  the 
bed  of  the  Landquart,  which  is  generally  fed  by  the  two  important  gla- 
ciers of  Sardasca  and  Silvretta,  did  not  receive  a  single  drop  of  water.* 
In  1839,  the  Arveiron  itself  was  entirely  dried  up.f 

The  mind  is  all  the  more  vividly  impressed  with  the  majesty  of  these 
great  rivers  of  ice  when  the  vegetation  surrounding  them  is  green  and 
luxuriant,  and  forms  a  more  striking  contrast  with  the  white  and  blue- 
tinted  cliffs.  Some  of  the  most  beautiful  glaciers  in  the  Alps  descend 
right  down  into  the  midst  of  forests  of  firs,  beeches,  and  larches ;  and  it 
is  through  the  green  foliage  of  the  trees  that  we  catch  a  glimpse  of  the 
white  waves  of  the  icy  sea  and  the  dark  walls  of  the  moraines.  In  other 
places,  fields  of  corn,  or  even  vineyards  and  gardens,  extend  to  the  very 
base  of  the  solid  river,  and  sometimes,  it  is  said,  they  have  to  mount  upon 
fallen  blocks  of  ice  in  order  to  gather  the  fruit  off  the  branches  of  the 
cherry-trees.  Thus  the  cultivation  of  the  temperate  zone,  and  the  ice- 
fields of  the  pole,  which  on  the  continent  itself  are  separated  from  each 
other  by  thousands  of  miles,  are  here  brought  into  close  juxtaposition ; 
man's  labor  and  Nature  in  her  inviolable  grandeur  come  in  contact  here 
without  the  least  transition.  This  sudden  passage  into  a  virgin  region, 
devoid  of  all  activity,  conveys  an  effect  of  grandeur  which  deeply  im- 
presses the  soul.  It  is  difficult  to  restrain  a  species  of  dread  at  the  sight 
of  these  enormous  rivers  of  ice  slowly  marching  on,  from  century  to  cen- 
tury, with  their  white  or  bluish  layers,  300  feet  high,  descending  gradu- 
ally, en  masse,  a  few  inches  a  day,  carrying  with  them  the  fragments  of 
mountains,  and  grooving  out  in  their  course  deep  furrows  in  the  bed  of 
rock  through  which  they  flow.  These  glaciers  seem  as  motionless  as  the 
peaks  which  tower  over  them,  and  yet  they  roll  on  as  surely  as  the 
stream  to  which  they  give  rise.  The  solid  waves  which  roughen  their 
surface  rise  and  fall,  in  the  long  run,  just  as  those  of  the  sea.  They,  too, 
have  their  eddies  and  their  whirlpools ;  and  the  mighty  moraines  which 
they  throw  from  them  at  the  outlets  of  their  gorges  are  as  much  an  al- 
luvium as  the  mud  or  sand  of  a  river  or  the  deposits  forming  along  the 
sea-shore. 

*  William  Huber,  Lea  Glaciers.  t  De  Charpentier,  Ussai  sur  les  Glaciers. 


GLACIERS    OF   LANGTHAL    AND   GURGL.  PL.Xlll 


Cold»  Cmryl 


>>, 


*tcto 
Scale      in    Yards 


soo  moo         iKv         taco 


Engtily  ErXard,i2rDuguay-1Vouiii.  Drami  by  A.ViiiUeiiim    alter  Sonldir. 

HARPER  &.  BROTHERS,  NEW  YORK 


ADVANCE  Aim  RETREAT  OF  GLACIERS.  •  £01 


CHAPTER  XXXIV. 

PEOGBESS    AND    KETIEEMENT    OP    GLACIERS. APPEARANCE    OP    THE    BED 

WHEN  ABANDONED  BY  THE  ICE. BOCHES  MOUTONNEES. PARALLEL  FUR- 

ROAVS. 

In  several  parts  of  the  Alps  the  mountaineers,  influenced  by  the  super- 
stitious ideas  of  former  days,  continue  to  believe  that  the  base  of  a  gla- 
cier advances  and  recedes  alternately  every  seven  years.*  The  fact  is, 
that  if  the  progress  and  retreat  of  the  fields  of  ice  take  place  under  the 
influence  of  any  regular  law,  this  law,  which,  at  any  rate,  must  be  dis- 
turbed by  a  host  of  special  local  phenomena,  has  not  yet  been  discov- 
ered. Since  the  date  when  regular  observations  first  began  to  be  made 
on  the  forward  motion  of  the  Alpine  glaciers,  they  have  been  subject  to 
very  considerable  fluctuations  in  their  movements.  Sometimes  they  have 
advanced,  sometimes  they  have  receded,  and  sometimes,  even,  they  have 
remained  stationary  for  several  years  together ;  but  it  appears  that,  on 
the  whole,  they  have  moved  onward.  Several  of  the  Swiss  glaciers — 
those  of  Zmutt,  Aletsch,  the  Rhone,  the  Aar,  and  Grindenwald — have  in- 
creased in  length  in  their  rocky  beds. 

It  appears  to  be  certain  that,  in  spite  of  temporary  retirements,  some 
fields  of  ice,  even  in  the  last  century  or  two,  have  extended  sufficiently 
to  close  mountain  passes  which  were  once  practicable  even  for  horses. 
Thus,  several  passes  in  the  groups  of  Mont  Blanc,  Monte  Rosa,  and  the 
Bernese  Oberland,  which  still  remained  open  in  the  fifteenth  century,  and 
were  indeed  used  for  troops,  became  more  and  more  difficult  to  cross,  and 
ultimately,  during  the  course  of  the  eighteenth  century,  have  been  ren- 
dered inaccessible,  either  for  horsemen  or  pedestrians.f  The  Lotschen- 
pass,  near  the  Gemmi,  which  was  used  less  than  a  century  back,  is  now 
closed  up.  Several  facts  of  this  kind  are  instanced  in  the  Tyrol.  One  of 
the  CEtzthal  glaciers,  that  of  Gurgl,  has  certainly  advanced  a  mile  and  a 
quarter  since  the  year  1717,  for  that  was  the  date  when  it  commenced  to 
dam  up  the  side  valley  of  Langenthal,  in  which  the  stream  has  accumu- 
lated to  form  a  lake.  J  In  like  manner,  in  Asia,  the  glaciers  of  the  Kara- 
korum  seem  to  have  uniformly  advanced  during  the  course  of  a  century 
at  least.  The  pass  of  Jusserpo  was  formerly  accessible  to  horsemen  ;  it 
can  now  only  be  crossed  on  foot.  -The  glacier  of  Baltoro  and  the  ancient 
pass  of  the  Mustack  have  become  impracticable.§    But  this  is  not  all, 

*  William  Huber,  Les  Glaciers. 

t  Venetz,  Denkschriflen  der  Schweizeriachen  Gesellschnfl,  Part  I.,  1830. 

*  Sonklar,  (Etzthaler  Gebirgsgruppe. 

§  Godwin-Austen,  Journal  of  the  Geographical  Society  of  London,  1846. 


202  •  ^^^  EARTH. 

several  Alpine  glaciers  are  named  as  being  of  recent  formation.  Among 
these  are  the  Dreckgletscherli  ("  little  glacier  of  mud  ")  of  the  Fauldhorn, 
which  was  not  in  existence  at  the  commencement  of  the  century ;  the 
Rothelch,  a  field  of  ice  on  the  Simplon,  dates  from  1731 ;  another,  de- 
scending from  the  Galenhorn,  in  the  valley  of  Saas,  was  formed  in  1811; 
lastly,  the  fine  Glacier  de  Rosenlaui  itself  is  of  modern  origin.* 

Are  the  glacial  encroachments  which  have  taken  place  on  various 
mountain  chains  to  be  attributed  to  some  cause  acting  generally  over  the 
whole  planetary  surface  ?  This  is  the  idea  which  M.  Adhemar  asserted, 
which,  too,  is  still  maintained  by  his  disciples.f  According  to  their  view, 
the  gradual  cooling  of  the  northern  hemisphere  during  the  present  period 
is  completely  proved  by  the  increase  of  the  glaciers  of  Greenland,  the 
Alps,  and  the  Himalaya ;  but  the  observations  made  up  to  the  present 
time  are  neither  numerous  nor  decisive  enough  to  authorize  any  such  con- 
clusion. And  even  if  there  was  a  uniform  advance  into  the  valleys  on 
the  part  of  glaciers  every  where,  their  progress  might  also  be  attributed 
to  an  increase  of  the  humidity  contained  in  the  air,  or  to  some  change  in 
the  general  direction  of  winds.  Numerous  instances  may  be  mentioned 
of  glaciers  existing  on  the  flanks  of  the  same  mountain,  advancing  with 
more  or  less  rapidity  according  to  the  quantity  of  snow  that  falls  directly, 
or  is  displaced  after  its  fall  by  the  atmospheric  cuiTents.  Sometimes, 
even,  a  glacier  has  been  noticed  to  increase'  in  length,  while  near  it,  or  on 
the  opposite  side  of  the  mountain,  another  field  of  ice  has  diminished  in 
size.  Phenomena  of  this  kind  are  evidently  owing  to  the  unequal  distri- 
bution of  snow  on  the  various  slopes.  Very  considerable  falls  of  debris 
on  the  surface  of  a  glacier  will  also  result  in  the  prolongation  of  the  icy 
current  into  the  valley,  because  the  layer  of  rubbish  causes  the  annual 
ablation  to  decrease  to  a  very  important  extent.  Perhaps,  even,  as  Otto 
Volgar  points  out,  the  gradual  upheaval  of  certain  mountain  groups  is 
also  one  of  the  causes  which  contribute  to  the  extension  of  rivers  of  ice.J 

Nevertheless,  if  during  modern  times  a  certain  number  of  glaciers  have 
unquestionably  advanced,  others  have  certainly  receded,  and  consequently 
their  bulk  has  become  lessened.  Thus,  in  the  Pelvoux  group  the  two  im- 
portant glaciers  of  Bonnepierre  and  Chardon  have  continued  to  decrease 
in  length  and  thickness  since  the  year  1850,  and  this  movement  of  con- 
traction was  still  continuing  in  1861.  In  like  manner,  in  the  Tyrolese 
Alps,  all  the  glaciers  of  the  Adamello  group  are  diminishing  regularly. 
The  Mandron,  the  most  important  of  all,  has  been  retiring  at  least  since 
1825,  and  in  the  year  1864  especially  had  lost  about  66  feet  of  its  length. 
In  the  same  year,  the  glacier  of  Fargorida  lost  nearly  100  feet,  and  the 
inhabitants  of  the  country  say  that  since  the  beginning  of  the  last  centu- 
ry it  has  continued  to  diminish  in  importance.!  It  appears  also  that,  in 
certain  places,  the  fields  of  ice  reposing  on  the  summits  have  also  disap- 
peared. 

*  Tschudi,  Le  Monde  desAIpes,  vol.  iii.  t  Vide  above,  p.  67. 

}  Untersuchungen  iiber  das  Phdnomen  der  Erdbehen,  voL  ii.  §  Payer,  Adatnello-Gruppe. 


MOTION  OF  THE  ICE  STREAM.  203 

During  the  forty  years  which  have  elapsed  from  1826  to  1866,  the  gla- 
ciers of  Mont  Blanc  have  also  lost  much  both  of  their  length  and  of  their 
force,  evidently  because  the  snow  in  winter  has  been  less  abundant,  and 
the  summers  on  the  average  have  been  hotter.  The  Glacier  du  Tour, 
which  once  invaded  the  valley  of  Chamounix,  has  retreated,  on  the  whole, 
567  yards  since  1854,  and  does  not  reach  beyond  one  of  the  upper  pas- 
sages, invisible  from  the  road.  A  stone  which  marks  the  precise  spot 
reached  by  the  Glacier  des  Bois,or  Mer-de-Glace,  in  1826,  stood,  in  1865, 
at  424  yards  from  the  arch  of  the  Arveiron,*  and  at  certain  spots,  accord- 
ing to  the  evidence  of  M.  Bardin,  the  ice  had  decreased  more  that  100 
yards.  The  Glaciers  des  Bossons  and  Argentidre,  the  two  other  great 
glaciers  of  the  valley,  each  of  which  used  to  threaten  the  village  that  was 
nearest  to  their  frontal  moratwe,  have  receded  362  yards  and  197  yards 
respectively  during  the  period  from  1854  to  1866.  Although  they  have 
diminished  in  length  more  slowly  than  the  Glacier  du  Tour,  it  is  evi- 
dently because  the  basin  which  tliey  occupy  is  much  more  considerable, 
and  the  neves  above  have  never  ceased  to  feed  them.  We  must  also  add 
that,  during  these  twelve  years,  the  superficial  ablation  has  in  every  case 
perfectly  coi-responded  with  the  retirement  of  the  ice.  The  Glacier  des 
Bossons  has  lost  about  88  yards. in  thickness.  Previously  to  1854, the 
lateral  moraines  lay  much  lower  than  the  mass  of  the  glacier ;  they  now 
tower  over  it  at  a  mean  height  of  82  feet.f 

The  true  system  of  action  of  glaciers  seems  to  be  pointed  out  by  the 
alternations  of  progress  and  retreat,  established  both  by  official  docu- 
ments and  scientific  observations  with  regard  to  the  lower  part  of  the 
Glacier  de  Vernagt,  in  the  (Ezthal  group.  The  fluctuations  of  this  river 
of  ice  have  been  noticed  for  nearly  three  centuries,  and  the  chronicler 
who  mentions  them  for  the  .first  time  in  1599  adds  that  these  motions  to 
and  fro  are  the  "  natural  habit "  of  the  glacier.  The  Vernagt  descends 
rapidly  toward  the  valley,  and,  striking  against  a  wall  of  rock  which 
rises  up  directly  opposite  to  it,  obstructs  the  passage  of  the  Rosenthal 
waters,  which  there  form  a  lake.  Then  the  enormous  obstacle  gradually 
sinks,  the  glacier  slowly  recedes  toward  the  steep  slopes,  until  some 
fresh  impulse  of  the  neve  again  forces  it  on  toward  the  bottom  of  the 
valley.  Without  reckoning  the  less  important  fluctuations,  we  find  that 
the  intervals  between  each  great  enlargement  have  been  seventy-eight, 
ninety-three,  and  seventy-three  years,  which  gives  an  average  of  eighty- 
four  years.  Like  rivers  of  running  water,  the  Glacier  de  Vernagt  has  its 
floods  and  low-water  seasons.  From  1843  to  1847,  at  the  time  of  the  last 
irruption  of  the  ice,  it  advanced  1455  yards,  and  spread  out  in  the  valley 
over  a  width  of  1382  yards.  At  the  lower  part  the  ice  was  not  less  than 
518  feet  above  the  stream,  and,  higher  up,  the  glacier,  at  certain  spots, 
attained  a  thickness  even  twice  as  great.  The  swiftness  of  progression 
of  the  front  of  the  glacier  was  quite  unexampled.     During  the  first  two 

*  Payot,  Bibliotheque  de  Geneve,  September,  1866. 
t  Martins,  Bibliotheque  de  Geneve,  July,  1866. 


204  ^^-^  EARTH. 

years  it  exceeded  6^  feet  a  day ;  at  the  end  of  the  month  of  May,  1 845, 
it  attained  a  rate  of  progress  of  42  feet  in  the  twenty-four  hours.  On  the 
1st  of  June  the  speed  measured  was  not  less  than  6  feet  3  inches  an  hour, 
equal  to  about  150  feet  in  one  day.  The  motion  of  the  ice  could  be  de- 
tected even  with  the  naked  eye.  The  thunder  of  the  opening  crevasses 
and  of  the  seracs  falling  down  was  incessant.  Finally,  however,  this  ter- 
rible invasion,  which  threatened  all  the  valleys  below,  was  arrested,  and 
the  stream  of  ice  receded,  giving  a  passage  to  the  lacustral  waters  which 
it  had  penned  back.  Since  this  epoch  the  lower  portion  of  the  Glacier  de 
Vernagt  has  continued  to  decrease,  but  still  here  and  there,  on  its  former 
bed,  it  has  left  islands  of  ice  protected  against  the  heat  of  the  sun  by 
masses  of  debi-is.  After  resisting  the  elements  for  years,  these  isolated 
heaps  sink  and  finally  disappear.* 

By  means  of  the  temporary  or  permanent  retirement  of  certain  glaciers, 
we  are  enabled  to  ascertain  the  eifect  produced  by  the  gradual  flow  of 
these  enormous  masses  on  the  bottom  and  sides  of  their  rocky  beds. 
The  numerous  observations  of  M.  Dollfuss  -  Ausset  seem  to  have  estab- 
lished the  fact  that  above  8530  feet,  that  is,  above  the  ideal  line  of  per- 
petual snow,  the  Alpine  glaciers  only  rub  away  the  stone  in  a  quite  im- 
perceptible degree,  on  account  of  the  freezing  which  causes  them  to  ad- 
here to  the  surface  of  their  bed.  But  below  this  altitude  the  incessant 
friction  of  the  ice  and  the  gravel  it  carries  with  it  gradually  removes  the 
most  prominent  roughness,  and  ultimately  gives  a  rounded  surface  to  all 
the  projections.  To  use  a  comparison  which  is  frequently  applied,  a 
glacier  passes  over  the  ground  like  a  gigantic  plane;  it  works  over  the 
bottom  of  its  bed,  and  overriding  all  the  projecting  points,  grinds  them 
down,  pulverizes  them,  and  reduces  them  to  the  condition  of  sand.  It 
subsequently  makes  use  of  this  very  debris  for  rubbing  away  and  polish- 
ing the  rocks  in  its  bed ;  hence,  therefore,  arises  that  mammillated  aspect 
of  the  old  projections  over  which  the  heavy  mass  has  glided  for  so  many 
centuries.  Clefts  and  fractures  appear  like  dark  lines  of  shade  on  these 
round,  white,  polished  lumps,  which  sometimes  have  the  appearance  of 
heaps  of  wool  placed  upon  the  ground,  or  of  flocks  of  sheep.  They  are 
thus  known  under  the  name  of  roches  moiUonnees,  a  name  employed  for 
the  first  time  by  De  Saussure. 

In  making  its  way  toward  the  plain,  the  glacier  does  not  confine  itself 
to  rubbing  off  the  more  prominent  parts  of  the  rock ;  it  also  scoops  out 
the  stone  in  certain  places  by  means  of  the  variously-shaped  blocks  of 
grater  or  less  hardness  with  which  it  is  armed  on  its  lower  face,  which 
act  as  so  many  chisels  on  the  rocks  beneath  them.  The  stones  which  are 
slowly  impelled  toward  the  bottom  of  the  glacier  are  scratched  as  by 
stylets  of  stone,  and  the  rocky  bottom  of  the  gorge  itself  is  furrowed  up 
and  down  as  by  a  ploughshare.  The  walls  of  the  bed  of  ice  are  likewise 
grooved  by  the  rough  edges  of  the  blocks  carried  along  on  each  side  of 
the  current.  Nevertheless,  wherever  the  bed  of  the  glacier  is  narrowly 
*  Sonklar,  (Etzthaler  Gebirgsgruppe. 


GLACIER  OF   VERNAGT 
ill  the  Autumn  of  18r>6 


PI .  XIV 


GusLubcT^I 


Flaaeiberg 


S>     *•  Wff 


Yards 


leS  Tmrd» 


r^-- 


Section  tak<>n  at  tbe  liae  A  D 


Ir^^    ty     Erhard,  lar.DuJuay-TroTjjn  Drawn  Ly    A  Vuillerr.in     aftfir    Karl  Soi\ilaT. 

HAP.PER  &.  BROTHERS.  NEW  YORK 


ICE-PLANINO  AND  GROOVING.  205 

confined  between  two  promontories,  it  is  only  the  up-stream  faces  of  the 
latter  which  present  streaks,  furrows,  or  other  traces  of  rubbing,  and  the 
down-stream  faces  retain  all  their  natural  clefts  and  original  projections. 
Sometimes,  in  portions  of  the  bed  abandoned  by  the  ice,  we  may  meet 
with  circular  cups  or  basins,  like  the  holes  which  the  sea  or  rivers  hollow 
out  on  their  shores.  These  glacier -cups  originate  in  a  similar  way  to 
those  in  river  banks  and  cliffs:  they  are  formed  by  stones  incessantly 
turning  round  and  round  under  the  influence  of  sub-glacial  torrents,  or 
the  cascades  pouring  down  into  the  gulfs  of  the  moulins. 


206  ^^^  EARTH. 


CHAPTER  XXXV. 

DISTRIBUTION   OF  GLACIERS    OVER   THE    SURFACE    OP   THE   EARTH. 

Mountain  summits  which  rise  ahove  the  limit  of  perpetual  snow  do  not 
all  give  rise  to  rivers  of  ice ;  the  concurrence  of  several  meteorological 
and  orographical  conditions  is  necessary  in  order  that  the  snow  and  nem 
should  be  changed  into  glaciers.  In  the  first  place,  it  is  requisite  that  the 
snow  zone  of  the  mountain  tops  should  be  of  some  considerable  breadth, 
and  that  vast  beds  of  neve — those  reservoirs  for  the  supply  of  glaciers — 
should  be  formed  in  the  mountain  amphitheatres  and  in  the  upper  pla- 
teaux. It  also  requires  that  the  winds  which  blow  against  the  mount- 
ains should  be  charged  with  an  amount  of  humidity  sufficient  to  leave 
immense  beds  of  snow  on  the  summits  and  the  slopes.  Added  to  all  this, 
the  gorges  which  open  into  the  thickness  of  the  chain  must  be  of  a  gen- 
tle inclination,  so  that  the  snow  may  not  slide  down  immediately  into  the 
valleys  below  in  the  form  of  avalanches ;  and  the  mountains  themselves 
must  be  grouped  in  such  a  way  that  their  gorges  unite  to  form  a  common 
basin,  where  the  snow  may  be  finally  elaborated  in  order  to  constitute 
genuine  rivers  of  ice.  Lastly,  it  is  indispensable  that  the  various  seasons 
of  the  year  should  aflford  extremes  of  temperature  sufficiently  great  to 
allow  of  the  phenomena  of  thawing  and  regelation  taking  place  in  the 
masses  of  neve.  It  is  owing  to  the  great  uniformity  of  climate  that  so 
little  ice  is  seen  on  the  sid^s  of  the  lofty  snow-clad  peaks  of  the  equato- 
rial Andes. 

The  large  number  of  different  conditions  which  must  all  be  combined 
as  necessary  to  the  formation  of  glaciers  will  readily  show  why  these 
rivers  of  transformed  snows  are  comparatively  very  rare  in  the  regions 
of  torrid  and  temperate  zones.  They  are  produced  with  a  high  degree 
of  uniformity  and  grandeur  only  on  the  sides  of  lofty  summits;  while  on« 
mountains  of  less  elevation,  as  those  of  the  Vosges*  and  the  Riesenge- 
birge,  they  are  formed  in  very  snowy  years  in  the  recesses  of  ravines  shel- 
tered from  the  sun.  It  is,  however,  only  in  the  vicinity  of  the  poles  that 
the  ice-system  manifests  all  its  magnificence,  and  indeed  constitutes  the 
predominant  feature  of  nature. 

In  Europe,  the  Central  Alps  form  the  orographical  system  in  which  all 
the  conditions  necessary  for  the  formation  of  glaciers  are  fulfilled  at  the 
greatest  number  of  points.  These  mountains,  too,  will  ever  remain  for 
savants  the  classical  region  of  glaciers,  for  among  them  a  De  Saussure,  a 
Charpentier,  an  Agassiz,  a  Rendu,  a  Forbes,  and  a  Tyndall  have  gone  on 
from  discovery  to  discovery,  and  have  ultimately  brought  to  light  the 
*  CoUomb,  Comptes  Rendus  de  FAcademie  des  Sciences,  1846,  vol.  xxi. 


OLACIERS  OF  THE  ALPS. 


207 


true  theory  of  the  motion  of  ice.  There  are  in  the  Alps  nearly  1100  gla- 
ciers, a  hundred  of  which  may  be  looked  upon  as  primary  glaciers.*  The 
total  surface  of  the  fields  of  snow,  weye,  and  ice  on  the  Alps  is  estimated 
by  the  brothers  Schlagintweit  at  117V  square  miles,  or  about  one  seventh 
of  the  whole  area  of  the  great  mountains  from  the  Pelvoux  to  the  Gross- 
Glockner.  The  glaciers  of  Mont  Blanc  alone,  though  inferior  in  extent  to 
those  of  Monte  Kosa,  cover  a  surface  of  109  square  miles.  According  to 
M.  Iluber,  their  total  mass  amounts  to  nearly  1834  millions  of  cubic  yards, 
and  represents  a  body  of  water  equal  to  the  whole  of  the  discharge  of  the 
Seine  during  nine  years. 

The  glaciers  of  the  Alps  descend  on  the  average  to  a  point  about  7414 
feet  above  the  level  of  the  sea,  that  is,  about  1650  to  2000  feet  below  the 
level  of  perpetual  snow ;  but  there  are  a  great  number  of  glaciers,  and 
they  are  generally  the  most  important,  the  base  of  which  is  below  the 


Jcn|ft«u  PiiuteraMSiorn 


irm 


0286 


JbtntBIano  HonteBosib  "  Alp^  Alps  of  Glaris 

Fig.  69.  Glaciers  of  the  Alps — after  A.  and  il.  >chiagintweit. 
a,  a,  Lower  limit  of  persisteut  snows.  b,  b.  Lower  limit  of  secondary  Glaciers. 


mean  altitude  of  about  7000  feet.  The  Mer-de-Glace,  the  receptacle  of 
the  greatest  part  of  the  snow  of  Mont  Blanc,  reached  in  1862,  at  the 
source  of  the  Arveiron,  a  point  which  is  only  3659  feet  above  the  level  of 
the  sea.  The  Glacier  des  Bossons,  fed  by  the  snow  of  the  same  mount- 
ain group,  descended  to  a  level  of  3605  feet ;  lastly,  the  lower  glacier  of 
Grindenwald,  which  of  all  the  glacie^  in  the  Alps  pushes  its  way  the  far- 
thest into  the  valleys  below,  has  its  terminal  grotto  placed  at  only  3225 
feetf  above  the  sea-level.  This  fact  must  be  attributed  to  the  northern 
aspect  of  the  glacier,  to  the  narrow  straits  of  rocks  through  which  it  has 
to  flow,  and  its  rapid  declivity,  exceeding  14  degrees.  With  regard  to 
the  Glacier  d'Aletsch,  which  in  its  dimensions  is  the  most  important  of  all, 
and  rolls  down  a  wide  current  over  a  total  length  of  23,304  yards,  it  does 
not  descend  into  the  lower  gorges,  and  in  1860  it  stopped  at  an  altitude 
of  5137  feet  above  the  level  of  the  sea.      The  Glacier  d'Aletsch  owes 

*  The  brothers  Schlagintweit.  The  Bavarian  savants  have  omitted  in  their  list  many  gla- 
ciers both  of  the  Western  and  even  the  Central  Alps.  The  ice  area  in  these  mountains  is 
probably  somewhat  larger  than  they  have  estimated  it. 

t  Sthder,  Bibliothique  de  Genh>e,  September,  1806. 


208 


THE  EARTH. 


its  enormous  development  to  the  great  body  of  nkve  collected  in  the 
high  mountain  hollows.  This  glacier  nas  a  total  area  of  no  less  than 
130,000,000  square  yards. 


1^.  ,.>&.'*-"^ 


• •"  •■r  -  ..>■■  "  . 


Fig.  70.  The  Glacier  d'Aletsch. 


The  glaciers  of  the  Tyrol  are  numerous,  since,  in  the  (Etzthal  and  Stu- 
baier  groups  alone,  Sonklar  reckons  309  glaciers,  16  of  which  are  of  the 


GLACIERS  OF  THE  ALPS.  209 

tirst  class.  It  is  true  that,  in  his  enumeration,  the  learned  explorer  of  the 
OEtzthal  has  not  omitted  a  single  one  of  the  small  glaciers  lying  on  the 
sides  of  the  mountains.  Some  of  the  rivers  of  ice,  especially  the  Vernagt, 
the  Gepaatch,  the  MurzoU,  and  the  Gurgl,  are  important  streams,  and  well 
known  to  savants  through  the  investigations  of  the  brothers  Schlagint- 
weit.  Simony,  Sonklar,  and  other  geologists ;  they  are,  howevei*,  inferior 
in  extent  to  the  principal  Swiss  glaciers.  This  minor  importance  of  the 
Tyrolese  ice-rivers,  compared  with  those  of  the  Western  Alps,  is  principal- 
ly to  be  attributed  to  the  unequal  distribution  of  snow  in  the  two  coun- 
tries during  the  various  seasons  of  the  year.  Not  only  does  it  rain  and 
snow  in  larger  quantities  on  the  Swiss  mountains  than  on  those  of  the 
CEtzthal,  but  in  the  latter  groups  the  snow  falls  principally  in  summer, 
and  consequently  melts  before  it  has  a  chance  of  increasing  the  mass  of 
the  glacier.  The  winter  snows,  which  alone  contribute  to  feed  the  ice- 
rivers,  are  more  than  twice  as  abundant  on  the  lofty  summits  of  Switzer- 
land as  on  those  of  the  Tyrol.*  The  annual  layer  of  neve  which  is  formed 
on  the  Bernese  Alps  attains,  according  to  Agassiz,  a  thickness  of  2  to  2\ 
yards,  while  on  those  of  the  CEtzthal  it  scarcely  reaches  a  yard.  Never- 
theless the  latter  group  affords  an  area  of  221  square  miles  of  ice,  equal 
to  one  seventh  of  its  whole  surface. 

The  two  other  principal  groups  of  the  Eastern  Alps  are  those  of  the 
Ortelspitze,  south  of  the  CEtzthal,  and  the  Gross-Glockner,  very  much 
more  to  the  east.  In  the  latter  is  situated  the  fine  glacier  of  Pasterze, 
the  dimensions  of  which,  including  the  neve,  are,  according  to  the  broth- 
ers Schlagintweit,  10,274  yards  in  length,  4494  yards  in  width,  and  236 
yards  in  depth.  The  rest  of  the  Austrian  Alps  possess  only  two  isolated 
glaciers,  that  of  Dachstein,  not  far  from  Hallstadt,  and  that  of  Marmolata, 
above  the  plains  of  Venetia.f  In  order  again  to  meet  with  these  mighty 
ice-Vivers,  we  must  turn  to  the  other  extremity  of  the  Alpine  system,  to 
the  south  and  southwest  of  the  great  central  groups  of  Monte  Rosa  and 
Mont  Blanc.  There  each  of  the  great  groups  of  Piedmont  and  Dauphiny, 
the  Grand-Paradis,  the  Vanoise  and  Grande^Casse  groups,  the  Grandes- 
Rousses,  and  especially  the  Oisans,  afford  glaciers  of  the  highest  im- 
portance. 

The  mountains  of  Oisans,  Pelvoux,  the  Ecrins,  and  Aiguille-de-Meije  are 
almost  as  distinguished  as  Mont  Blanc  itself  in  the  quantity  of  ice  they 
bear  on  their  slopes.  There  is  no  region  in  the  Alps  in  which  the  phe- 
nomena of  these  vast  ice-nvers  can  be  better  studied  than  in  the  upper 
valley  of  the  Banc,  situated  at  the  point  of  junction  between  the  Glacier- 
Noir  and  the  Glacier-Blanc,  at  the  foot  of  the  pyramid  of  Pelvoux.  Just 
at  the  spot  where  the  lower  extremities  of  these  mighty  masses,  now  con- 
fined between  two  vertical  walls  of  ice,  unite  their  lateral  moraines,  they 
present  a  most  perfect  and  striking  contrast.  As  viewed  from  the  plain 
of  debris  lying  between  the  two  moraines,  which  is  traversed  by  the 

*  Sonklnr,  (Etzthaler  Gebirgsgruppe. 

t  Adolf  Schmidt,  Oesterroichische  Vaterlandskunde. 

o 


210 


THE  EARTH. 


Stream  of  the  Banc,  the  Glacier-Noir  is  so  loaded  with  detritus  of  every 
kind  that  it  looks  like  an  immense  flow  of  mud,  such  as  those  vomited 
out  by  the  volcanoes  of  Java.  The  real  nature  of  this  mass  could  not  be 
recognized,  were  it  not  for  the  gaping  crevasses  into  which  blocks  of 
stone  and  trains  of  pebbles  ceaselessly  fall  with  a  dull  noise.  At  the  foot 
of  tlie  glacier  leans  the  frontal  moraine^  more  than  300  feet  high,  with 
muddy  rivulets  trickling  through  its  rocks  and  creeping  away  slowly 
among  the  scattered  debris  of  the  plain.  On  the  other  side  the  Glacier- 
Blanc,  almost  entirely  free  from  rubbish,  is  terminated  by  gigantic  steps, 
themselves  supported  by  vertical  buttresses  somewhat  resembling  a  lion's 
paw.  The  beds  are  of  a  pure  white,  here  and  there  streaked  with  red  and 
gold  color.  From  the  middle  arch,  which  is  admirably  curved  and  sup- 
ported by  blue  pilasters,  flows  the  tributary  of  the  Banc,  with  water  of  a 
milky  white.  To  the  east,  on  the  other  side  of  the  valley,  stands  the  Pel- 
voux, resembling  a  Gothic  spire  enriched  with  turrets;  between  each  of 
its  peaks  there  are  small  fields  of  ice,  which  look  in  the  distance  like  slabs 
of  white  marble. 

To  the  south  of  the  important  Oisans  group,  the  glaciers  only  appear 
singly  in  the  upper  gorges  of  the  loftiest  mountains.  In  no  place  do 
these  small  isolated  streams  combine  to  form  an  ice-river  which,  like  those 
of  the  great  Central  Alps,  pushes  its  way  down  into  the  valleys  at  the 
base  of  the  mountains.  The  Viso,  and  some  peaks  of  the  Maritime  Alps, 
present  small  ice-fields ;  the  last  in  this  part  of  the  chain  is  that  of  Cla- 
pier-de-Pagarin,  between  Nice  and  Valdieri. 

If  we  comprehend  in  one  glance  the  whole  map  of  Central  Europe,  we 
shall  see  that  the  princiiial  glacier  groups  are  those  which  surround  the 
mountain  summits  of  Mont  Blanc,  Monte  Rosa,  the  Finsteraarhorn,  Berni- 
na,  and  OEtzthal.  The  following  table,  from  which  we  clearly  see  that 
Monte  Rosa  is  the  true  centre  of  the  region  of  ice,  shows  the  comparative 
importance  of  each  system  of  glaciers.*  According  to  Studer,  it  is  owing 
to  the  heightening  of  the  temperature  produced  by  the  lofty  plateaux  of 
Engadine,  tliat  the  fine  group  of  the  Bernina  is  distinguished  from  all  the 
rest  by  the  comparatively  small  quantity  of  ice  wliich  it  possesses.f 


Mont  RIanr. 

Monte  Rosa.    ' 

Fbuteraarhorn, 

Bemlns. 

CEUthal. 

Yards. 

Yards. 

Yar.li. 

Yards. 

Yards. 

Mer-<lc-G)ace . 

.  15,9C6 

Grfener....  16,T32 

AletPCh....  2C,246 

Mortirat..  10,170 

Gepaatch..  12,.'»57 

Ar>renticre . . . 

lft,607 

Ferpccle...  15,529 

Viesch....  16,185 

Forao 9,623 

Gurgl 10,986 

Bionnassay. . . 

10,498 

Zinal 11,701 

Unteraar..  15,088 

Hintereis..  10,001 

Findclen..  11,154 

Tschingcl..    9,514 

Murzoll  . . .    9,023 

Zmntt 9,404 

Lotschen..    8,630 

Mittelberg.    8,530 

Tnrtmann.    8,311 

Oberaar . . .    8,420 

Vernagt...    8,811 

Ried 8,311  1 

The  Pyrenees,  which  lie  more  to  the  south,  are  neither  so  high,  nor  so 
well  arranged  in  groups  as  the  Alps ;  they  consequently  afford  a  much 
less  extent  of  snow-fields  and  glaciers.     The  area  occupied  by  the  latter 

*  In  this  table,  which  is  borrowed  from  Sonklar  (CEtzthaler  Gehirgsgruppe),  glaciers  less 
than  eight  thousand  yards  in  length  have  been  omitted. 
t  Bibliotheque  cle  (ieneve,  September,  18G6. 


FORMER  GLACIERS  OF  THE  VALLEY  OF  THE  ADICE  PL.XV. 


*"  .''.v,'    li    (Vms, 


SecHon  of  the  fanner  Glaciers  of  tlieA'alley  bfibe  Adi^e 


Drawn  hj  A  VuUlemin.  after  Momils 

HARPER.  -^  BR0THJER3,  KS>W,  YORK 


EHgaiyErliardl. 


GLACIERS  OF  THE  HIMALAYAS.  211 

lias  not  at  present  been  brought  into  comparison  with  the  superficies  of 
the  whole  chain,  but  it  certainly  does  not  reach  a  hundredth,  and  perhaps 
not  even  a  thousandth,  part  of  the  total  surface.  The  Pyrenean  glaciers, 
"w;hich  are  about  a  hundred  in  number,  are  almost  QwixYeXy  serneillies^  or 
summit-glaciers,  and  do  not  descend  into  the  lower  valleys.  There  is, 
perhaps,  only  one — the  eastern  glacier  of  Vignemale — which  assumes  the 
shape  of  an  ice-river,*  and  the  spot  in  the  gorge  where  it  stops  is  as  much 
as  7208  feet  above  the  level  of  the  sea.  Nevertheless,  although  the  Pyre- 
nees can  not  be  compared  to  the  Alps  either  in  the  magnitude  or  the 
development  of  their  glaciers,  those  that  are  found  in  the  former  chain  are 
in  no  way  less  remarkable  for  their  deep  crevasses^  their  blue-tinted  walls, 
their  little  lakes  covered  with  thin  ice,  and  all  those  other  varied  phenom- 
ena which  confer  such  a  charm  on  the  study  of  the  Swiss  glaciers. 

The  Carpathians  are  entirely  devoid  of  glaciei*s.  The  mountains  of  the 
Caucasus,  which,  in  the  general  configuration  of  Europe,  may  be  considered 
as  the  chain  corresponding  to  that  of  the  Pyrenees,  are  much  richer  in  ice- 
fields. One,  the  Desdaroki,  descends  as  low  as  6495  feet  above  the  sea, 
which  gives  a  vertical  height  of  something  less  than  12,000  feet  to  the 
whole  of  the  Caucasian  snow  and  ice-fields,  between  the  lowest  moraine 
and  the  summit  of  Elburz,  rising  to  an  elevation  of  18,405  feet.f  Never- 
theless, the  glaciers  of  the  Caucasus  are  not  equal  to  those  of  the  Central 
Alps,  either  in  magnitude  or  beauty,  which  is,  no  doubt,  caused  by  the 
comparatively  small  quantity  of  rain  and  snow  which  falls  in  this  part  of 
the  Old  Continent,  and  also  by  the  large  amount  of  summer  heat  which 
prevails  there. 

The  most  important  glaciers  of  the  northern  temperate  zone  are  prob- 
ably the  enormous  ice-rivers  of  the  Himalayas  and  the  Karakorum.  In 
comparison  with  the  immense  flows  of  snow  which  descend  from  the  prin- 
cipal summits  of  Asia,  the  largest  glaciers  of  the  Alps  must  be  considered 
as  belonging  only  to  a  secondary  order.  The  largest  glacier  in  the  Indian 
mountains — that  of  Biafo,  in  the  valley  of  Chiggar  (Karakorum) — is  not 
less  than  36  miles  in  length,  more  than  21  miles  longer  than  that  of 
Aletsch,  in  Switzerland.  The  area  that  it  occupies  is  several  hundred 
square  miles  in  extent,  and  in  its  vicinity  there  are  other  ice-fields,  such 
as  the  Baltoro  and  Mustack,  which  are  but  little  inferior  in  magnitude. | 
The  quantity  of  ice  which  almost  entirely  fills  up  each  of  these  important 
valleys  of  the  Karakorum  can  not  be  estimated  at  less  than  ten  times  that 
which  lies  in  the  Mer-de-Glace  and  the  Mer-d'Aletsch.  It  is  a  very  re- 
markable fact,  in  regard  both  to  these  glaciers  arfd  those  of  the  Himalaya, 
that  the  ice-rivers  are  much  longer  and  more  abundant  on  the  southern 
side  of  the  mountain  than  on  the  colder  slopes  which  are  turned  toward 
the  north.     This  phenomenon  must  evidently  be  attributed  to  the  larger 

•  Russell-Killough,  Les  Grandes  Ascensions  des  Pyriniea. 
+  Behm,  Geographisches  Jahrbwh,  18G6. 

X  Montgomerie,  Mittheilungen  von  Petermann,  vol.  ii.,  1863.  Godwin- Austen,  Journal  of 
the  Geographical  Society,  Loudon,  18C4. 


212  THE  EARTH. 

quantity  of  snow  brought  by  the  south  wind,  and  impeded  in  its  course 
by  the  lofty  summits.* 

The  northern  mountain  chains  of  the  Old  World  are  of  considerably 
less  elevation  than  either  the  Alps  or  the  Himalayas,  and  do  not  present 
any  glaciers  so  remarkable  for  their  extent  as  those  of  the  great  central 
groups  of  Europe  and  Asia.  Nevertheless,  the  proximity  to  the  pole  com- 
pensates in  part  for  the  inferior  altitude  of  the  peaks.  Thus,  the  high 
plateaux  which  terminate  the  Scandinavian  mountains,  exposed  as  they 
are  to  the  winds  from  the  west,  so  fully  charged  with  aqueous  vapor,  pre- 
sent vast  fields  of  snow,  and  the  greater  part  of  the  ravines  which  sink 
down  toward  the  fiords  on  the  coast  are  filled  up  with  glaciers  descending 
as  low  as  1640  feet,  or,  as  in  the  case  of  the  Boudhusbraen,  even  to  967 
feet  above  the  sea.  Among  the  numerous  ice-rivers,  the  most  important  is 
that  of  Lodal,  which  flows  from  the  immense  weue-fields  of  the  Justedal ; 
it  is  nearly  five  miles  long  and  880  yards  broad,  and  descends  to  a  point 
only  1320  feet  above  the  level  of  the  sea.  The  total  area  of  this  glacier 
is  very  inferior  to  that  of  some  of  the  primary  Alpine  glaciers ;  it  is  esti- 
mated approximately  as  being  about  one  seventh  of  that  of  the  great  ice- 
stream  of  Aletsch. 

Although  the  Ural  Mountains,  like  the  Scandinavian,  are  situated  un- 
der a  very  high  northern  latitude,  they  do  not  possess  a  single  glacier, 
and  do  not  even  reach  the  limit  of  perpetual  snow.  On  their  summits, 
the  height  of  which  varies  from  4000  to  5000  feet,  there  are  no  continuous 
snow-fields  to  be  noticed  in  the  middle  of  summer — no  snow,  in  fact,  but 
isolated  drifts  in  the  cavities  of  the  rocks.  The  surprising  contrast  be- 
tween these  mountains  and  those  of  Scandinavia  may  be  explained  by  the 
inferior  quantity  of  rain-fall  which  is  discharged  in  the  former  region,  and 
doubtless  also  by  the  comparative  narrowness  of  the  chain  and  its  isola- 
tion in  the  midst  of  the  toundras,  which,  although  traversed  by  cold 
winds  in  winter,  in  summer  reflect  the  rays  of  a  burning  sun.f  Neverthe- 
less the  other  mountain  chains — much  loftier,  it  is  true — which  surround 
the  south  of  Siberia,  have  their  fields  of  perpetual  snow  and  their  rivers 
of  ice.  In  the  Altai,  the  glacier  of  Katounia  descends  to  a  point  which  is 
4068  feet  above  the  level  of  the  sea. 

Even  the  plains  of  those  desolate  regions  which  stretch  away  to  the 
north  of  the  continent  of  Asia  have  glacier-like  masses  in  which  nothing 
is  wanting  but  motion  to  make  them  resemble  those  of  the  Alps.  The 
snow,  driven  by  the  eddies  of  the  wind,  is  heaped  up  in  the  hollows  of  the 
ground,  so  as  to  form  complete  hillocks,  which  the  heat  can  not  entirely 
thaw  during  the  short  days  of  summer ;  and  after  the  middle  of  autumn 
these  heaps  again  begin  to  increase.  In  consequence  of  the  partial  melt- 
ing and  the  successive  freezings,  the  snow  composing  these  hillocks  is 
changed  first  into  nevh  and  then  into  ice,  pure  and  blue,  like  that  of  the 
Alps.  The  mass  presents  some  clefts,  caused  doubtless  by  the  sudden 
change  of  temperature,  but  it  does  not  shift  its  position  on  the  surface  of 
*  Thomson,  Hooker.  t  Hofmann,  Der  Ndrdliche  Ural. 


THE  ARCTIC  ICE-FIELDS.  213 

the  ground  as  glaciers  do ;  only  the  thaw-water,  produced  by  the  sun  on 
the  surface  of  the  mound  of  snow,  flows  down  its  sides  and  then  freezes 
again,  thus  giving  a  wider  base  to  the  hillocks.  Many  of  these  patches 
of  ice,  which  on  sloping  ground  would  serve  as  the  beginning  of  a  gla- 
cier, are  some  hundreds  of  yards  in  length. 

The  countries  of  the  Arctic  zone — Spitzbergen,  Jan-Mayen,  and  Green- 
land— are  the  domain  par  excellence  of  nk,v^  and  glaciers.  In  those  re- 
gions the  mountains  are  uniformly  covered  with  snow  above  an  altitude 
varying  from  900  feet  to  1500  feet,  and  the  fields  of  ice  which  flow  down 
into  the  valleys  reach  very  nearly  to  the  sea-shore.  The  few  travelers 
who  have  climbed  a  summit  from  the  height  of  which  a  vast  extent  of 
country  can  be  surveyed  have  seen,  in  that  part  of  the  horizon  which  is 
occupied  by  land,  little  else  than  an  immense  white  sheet,  pierced  here 
and  there  by  black  pointed  rocka 

The  glaciers  of  these  polar  regions  difier  in  no  way  from  those  of  the 
Alps,  except  that,  in  consequence  of  the  inferior  altitude  of  the  snow,  the 
neve  has  a  very  considerable  extent  as  compared  with  the  glacier  proper. 
Sometimes,  even,  it  has  been  asserted  that  the  lower  portions  of  the  ice- 
rivers  of  Spitzbergen  present  both  the  appearance  and  the  structure  of 
neve ;  this,  however,  is  an  error.  In  these  polar  countries  the  glaciers 
have  also  their  crevasses  and  their  moulins^  their  stratification  and  their 
blue  belts,  their  moraines  and  sub-glacial  streams.  Only,  the  thickness 
of  the  mantle  of  snow  which  covers  the  whole  country,  and  the  surface 
of  the  glacier  itself,  generally  give  it  a  considerable  uniformity  of  aspect; 
the  stones  of  the  7noraines  appear  on  the  surface  in  but  ^ew  spots,  and  as 
to  the  mass  of  debris  which  ought  to  accumulate  in  front  of  each  glacier, 
they  must  tfe  sought  for  in  the  bed  of  the  sea,  into  which  the  blocks  are 
precipitated  which  break  away  from  the  principal  mass. 

One  of  the  largest  ice-fields  in  Greenland,  next  to  Humboldt's  enormous 
glacier,  which  ^as  no  less  than  69  miles  wide  at  its  lower  extremity,  and 
those  still  grander  ones  discovered  by  Hayes,  the  American,  in  his  recent 
travels,  is  that  of  Eisblink,  south  of  Goodhaab.  Tlie  lower  portion  of  the 
enormous  mass  pushes  out  into  the  midst  of  the  sea,  forming  a  cape,  the 
length  of  which  is  more  than  13  miles,  and  if  a  glance  is  thrown  back  to- 
ward the  heights  between  the  two  walls  which  inclose  the  river  of  ice, 
the  Eisblink  may  still  be  seen  on  the  extreme  horizon — that  is,  35  to  40 
miles  away.  The  incline  of  this  sea  of  ice  is  very  gradual,  and  it  blends 
insensibly  with  the  horizontal  surface  of  the  icebergs  on  the  shore.  As 
the  glacier  does  not  terminate  on  the  ocean  coast  in  steep  cliffs,  it  is  im- 
possible to  discover  the  point  underneath  the  ice  which  forms  the  bound- 
ary between  land  and  water.  There  is,  however,  a  considerable  mass  of 
submarine  d^ris — the  Tallert  Bank — which  stretches  around  in  a  semi- 
circle in  the  sea,  just  oiF  the  end  of  the  glacier.  This  is  probably  a  kind 
of  frontal  moraine  carried  down  by  the  stream  which  incessantly  flows 
under  the  Eisblink. 

The  greater  part  of  the  streams  which  descend  from  the  mountains 


214:  THE  EARTH.  • 

in  the  interior  of  Greenland  likewise  remain  hidden,  during  their  whole 
couree,  under  enormous  moving  ice-fields,  and  only  betray  their  presence 
by  bubbling  up  in  different  places,  and  by  the  muddy  color  and  dimin- 
ished saltness  they  communicate  to  the  sea-water  with  which  they  are 
mingled.  Some  streams  which  pour  down  a  considerable  quantity  of 
water  hollow  out  for  themselves  wide  beds  under  arches  of  ice,  which 
press '  with  an  enormous  weight  on  the  pillars  that  support  them,  and 
which  are  always  tending  to  break  down  under  the  pressure  of  the 
masses  above.  At  the  same  time,  the  waves  of  the  sea,  the  temperature 
of  which  is  much  higher  than  that  of  the  glacier,  are  melting  away  the 
base  of  the  columns,  and  incessantly  sapping  them  by  their  repeated 
shocks.  This  frequently  results  in  the  downfall  of  immense  masses  of 
ice,  like  whole  sides  of  mountains,  which  give  way  suddenly  with  a  crash. 

The  downfall  of  one  of  these  terminal  cliffs  of  ice  in  Greenland  and 
other  Northern  countries  presents  a  magnificent  spectacle — as  in  the  gla- 
cier of  Horn  Sound,  on  the  south  of  Spitzbergen,  a  prodigious  mass,  150, 
300,  or  even  400  feet  high,  rests  entirely  on  the  sea,  which  has  gradually 
melted  away  the  under  portion  of  the  ice  with  which  the  waves  have 
come  in  contact.  At  low  tide  the  enormous  overhanging  mass,  under 
which  it  is  quite  possible  to  penetrate  in  a  boat,  hangs  without  support, 
and  is  only  kept  up  by  its  cohesion  with  the  rest  of  the  ice  and  with  the 
sides  of  the  adjacent  rocks.  Still  the  mass  continues  to  advance,  and  the 
numerous  partial  ruptures  which  take  place  in  its  bulk  cause  a  noise  sim- 
ilar to  the  crackling  of  the  electric  spark.*  All  of  a  sudden  the  great 
crash  takes  place ;  enormous  sections  of  ice  break  away  from  the  cliff 
with  a  roar  like  thunder,  and  sink  down  into  the  depths  of  the  water; 
they  soon,  however,  reappear  on  the  surface  of  the  waves,  oscillating  to 
and  fro  to  find  their  equilibrium,  and,  impelled  by  the  winds  and  cur- 
rents, float  away  on  the  undulating  billows. f 

In  the  continent  of  the  New  World,  the  glaciers  on*the  mountains 
farthest  to  the  north  resemble  those  of  Greenland  and  Spitzbergen  in 
likewise  reaching  the  sea-coast ;  but  in  the  south  the  lower  limit  of  gla- 
ciers rises  rather  rapidly.  In  a  gorge  at  Mount  Forbes,  situated  near  the 
52d  degree  of  latitude,  there  is  one  which  descends  to  the  point  of  4281 
feet  above  the  sea.  Mount  Renier,  between  the  46th  and  47th  degree, 
has  on  its  sides  small  glaciers  over  which  the  burning  lava  sometimes 
flows.  But  farther  to  the  south  there  are  no  other  summits,  either  of  the 
Rocky  Mountains  or  the  Sierra  Nevada  (not  even  those  that  rise  more 
than  13,000  feet  in  height),  which  have  on  them  fields  of  ice;  all  that  is 
to  be  seen  are  the  moraines  and  the  furrows,  telling  the  story  of  former 
glaciers  now  disappeared.  Neither  are  the  neves  of  the  Rocky  Mount- 
ains very  extensive — a  fact  which  may  be  explained  by  the  dryness  of 
the  air,  and  by  the  rapid  evapoi-ation  which  results  from  it. 

In  the  tropical  zone,  the  only  mountains  of  America  which  exhibit 
small  glaciers  are  the  lofty  summits  which  exceed  16,000  feet  in  height. 
*  Firfe  the  chaptfer  on  "Waters  of  the  Sea."  t  Charles  Martins. 


THE  AMERICAN  ICE-FIELDS.  215 

Of  this  kind  are  Orizaba ;  some  peaks  of  the  Sierra  Nevada,  of  Santa- 
Marta,  and  of  the  Sierra  of  Cocui,  in  New  Granada ;  the  Altar  of  Ecuador 
(the  former  crater  of  which  is  filled  up  with  ice),  and  Illimaui,  in  Bolivia.* 
Nevertheless,  these  small  glaciers,  aif  compared  with  the  extent  of  the 
neve  and  the  dimensions  of  the  mountain  chains  themselves,  have  no  geo- 
graphical importance,  I  may,  therefore,  be  allowed  to  repeat,  in  common 
with  most  other  authors,  that  the  Andes  are  devoid  of  ice  over  an  extent 
of  more  than  3000  miles,  from  the  confines  of  Venezuela  to  the  centre  of 
Chili.  The  Descabezado  de  Maule,  on  the  35th  degree  of  south  latitude, 
is  the  first  Chilian  mountain  on  which  we  find  an  ice-field.  But,  south 
of  the  peak,  glaciers  become  more  and  more  numerous,  and,  according  to 
Philippi,  present  in  their  structure  and  movement  the  same  varied  phe- 
nomena as  the  beautiful  glaciers  of  the  Alps.f  On  the  Patagonian  coast, 
south  of  Chiloe,  the  terminal  faces  of  the  glaciers  appear  in 'all  the  val- 
leys in  close  proximity  to  the  sea-shore.  Even  in  the  latitude  of  46°  50', 
a  position  corresponding  to  that  of  the  hills  of  Poitou,  in  the  northern 
hemisphere,  the  ice-rivers  make  their  way  to  the  sea,  and  the  fragments 
which  are  detached  from  them  go  floating  away  to  the  north.  The  fact 
is,  that  the  fall  of  rain  and  snow  is  very  considerable  on  the  western 
slopes  of  these  mountains ;  added  to  this,  it  is  a  matter  of  certainty  that 
the  mean  temperature  is  lower  in  the  southern  hemisphere  than  in  the 
northern.| 

Omitting  any  mention  of  the  glaciers  in  the  Antarctic  regions,  which 
have  never  been  closely  examined,  the  phenomena  of  which  must  exactly 
resemble  those  of  the  glaciers  of  the  northern  zone,  there  are  still  some 
very  remarkable  ice-rivers  in  the  southern  hemisphere  which  call  for  our 
notice.  These  glaciers  flow  down  the  sides  of  the  Alps  of  New  Zealand 
— the  great  southern  island.  The  glaciers  on  the  eastern  side  of  the 
chain  do  not  descend  so  low  as  those  on  the  western  slopes,  because  the 
quantity  of  rain  and  snow  poured  down  on  the  former  is  much  less  con- 
siderable. The  great  glacier  of  Tasman,  which  flows  toward  the  east, 
terminates  at  a  point  2739  feet  above  the  sea;  while  the  glacier  of 
Waiau,  which  fills  a  gorge  tending  toward  the  west,  descends  as  low  as 
700  feet  above  the  sea-level,  and  hurls  its  debris  among  the  green  ferns, 
pines,  beeches,  fuchsias,  and  other  plants  of  the  lowlands.  The  position 
of  this  glacier  (43°  35')  corresponds  with  the  latitude  of  Cannes  and  An- 
tibes  in  the  northern  hemisphere.  Now,  in  the  Sv/iss  Alps,  the  glacier 
which  descends  the  lowest  scarcely  attains  the  point  of  3300  feet  above 
the  sea.  We  must  go  twenty  degrees  farther  north,  to  the  coasts  of 
Norway,  to  find  the  most  southern  glacier  which  has  its  terminal  face  so 
little  above  the  sea  as  that  of  the  glacier  of  Waiau.  § 

♦  Behm,  Geofp-aphisches  Jahrbuch.  t  Mittheilungen  von  Petermann,  vol.  ^ni.,  1863. 

X  Firfc  the  chapter  on  "Climates." 

§  Julius  Haast,  Bulletin  de  la  Sociiti  de  Geographie,  Februar}'  and  March,  18GG. 


216  '  THE  EARTH. 


CHAPTER  XXXVI. 

THE  GLACIAL  PERIOD. — ANCIENT  GLACIERS  OF  EUROPE. — DISPERSION  OF 
ROCKS  AND  BOULDERS  FROM  SCANDINAVIA  AND  IN  NORTH  AMERICA. — 
ANCIENT   GLACIERS   IN   TROPICAL  REGIONS. 

A  STUDY  of  the  existing  phenomena  which  are  presented  to  us  in  the 
Alpine  glaciers  has  brought  to  light  the  unexpected  fact  that,  at  a  com- 
paratively recent  geological  epoch,  their  dimensions  were  much  more  con- 
siderable than  they  now  are.  Under  the  influence  of  meteorological  con- 
ditions which  certainly  difi'ered  from  those  of  the  present  period,  which 
conditions,  however,  are  still  the  subject  of  somewhat  animated  discus- 
sion, the  ice-rivers  descended  to  great  distances  from  the  ridge,  and  reach- 
ed the  extremity  of  some  valleys  Avhich,  during  the  present  epoch,  have 
become  richly-cultivated  tracts.  This  fact  is  evident  from  the  striae  run- 
ning along  in  parallel  lines  at  great  heights  on  the  mountain  sides,  also 
from  the  gigantic  moraines  which  in  times  gone  by  were  pushed  forward 
as  far  as  the  outlet  of  the  valleys,  and  the  rocks  which  were  formerly 
transported  by  the  ice  from  one  chain  of  mountains  and  thrown  upon  the 
opposite  slopes  of  another  chain.  Indications  of  a  perfectly  similar  char- 
acter to  those  which  mark  the  extent  of  the  comparatively  trifling  fluc- 
tuations of  the  glaciers  of  our  day  serve  also  to  measure  the  former  de- 
velopment of  the  enormous  ice-rivers  of  the  past. 

One  of  these  indisputable  signs  is  the  upper  limit  of  the  polls,  that  is, 
the  traces  of  rubbing  left  by  the  ice  in  its  course  toward  the  valleys.  It 
appears  that  on  the  sides  of  Monte  Rosa,  and  the  Bernese  Alps,  this  limit 
does  not  exceed  a  height  of  10,000  feet;  but  the  slope  of  most  of  the  ice- 
fields was  then  much  less  abrupt  than  it  is  at  present ;  it  did  not  exceed 
two  degrees,  and  at  some  points  on  the  banks  of  the  former  glacier  of  the 
Aar  it  was  even  less.  The  considerably  larger  quantity  of  the  ice  in  mo- 
tion at  that  time  allowed  the  whole  mass  to  make  its  way  over  a  very 
slightly  inclined  bed.  Fig.  71,  borrowed  from  M.  Desor's  work,*  will  give 
some  idea  of  the  dimensions  to  which  the  glaciers  of  the  Aar  formerly 
attained. 

In  like  manner,  the  glacier  of  the  Rhone,  which  now  occupies  a  mere 
gorge  in  the  Valais  Mountains,  filled  in  those  days  the  whole  space  in- 
cluded between  the  groups  of  the  Finsteraarhorn  and  Monte  Rosa,  and 
from  every  lateral  valley  and  every  ravine  which  opens  out  right  and  left 
in  the  thickness  of  the  chain  it  received  a  fresh  addition  of  ice  and  mo- 
raines. The  immense  ice-river  thus  extended  as  far  as  the  shore  of  the 
Lake  of  Geneva ;  it  even  went  beyond  it,  and  spread  over  the  plains  of 
*  Nouvelles  Excursions  et  Scjour  dans  les  Glaciers  dcs  Alpes. 


ANCIENT  OLACIEBS  OF  EUROPE.  217 

Switzerland  up  to  the  Jura,  joining,  at  its  lower  extremity,  the  glaciers  of 
the  Isere  and  the  Ain.  A  field  of  1000  feet  of  ice  stretched  over  the  val- 
ley at  the  very  spot  where  the  Rhone  and  the  Saone  unite  their  waters, 
and  where  the  city  of  Lyons  has  since  been  built.  On  the  Italian  slopes 
of  the  Alps,  each  of  the  great  valleys,  where,  in  the  present  day,  nothing 
but  a  few  fields  oftieve  are  to  be  found  in  some  of  the  higher  ravines,  used 


JerTrf  Keriof  Kive  Valley.  Valley 

Fiaslej-isr      Ladcraar  of  GauK  of  C&uli  of  iUi'J 

Fig.  71.  Ancient  Glaciers  of  the  Aar. 

to  serve  as  a  bed  for  vast  streams  of  ice,  descending  even  to  the  plains  of 
Piedmont  and  covering  the  great  Alpine  lakes.  One  of  these  streams, 
taking  its  rise  in  the  upper  ravines  of  Mont  Gen^vre,  Chaberton,  Mont 
Thabor,  Mont  Ambin,  Mont  Cenis,  and  Rochemelon,  filled  the  whole  of 
the  Susa  valley,  extending  even  to  Rivoli,  at  the  outlet  of  the  mountains. 
Another  glacier  filled  the  valleys  of  the  Adige,  and  advanced  beyond  the 
Lac  de  Garde ;  these  enormous  Alpine  glaciers  were,  in  fact,  twice  or  three 
times  the  size  of  the  largest  ice-rivers  which  are  now  to  be  found  in  the 
Karakorura  and  the  Himalaya. 

The  fonner  existence  of  these  glaciers  is  proved  not  only  by  the  pres- 
ence of  the  strim  and  marks  of  rubbing  on  the  rocks,  but  also  by  the  front- 
al and  lateral  moraines  which  have  been  pushed  forward  in  former  days 
to  the  very  outlet  of  the  valleys,  or  which  have  crumbled  down  on  the 
slopes.  Thus,  above  the  village  of  Monthey,  in  the  valley  of  the  Rhone, 
there  may  still  be  noticed  a  mass  of  stones  of  very  considerable  dimen- 
sions, forming  a  kind  of  rampart  more  than  3000  yards  in  length,  and  200 
yards  in  average  breadth.  This  bank  is  formed  of  granite  blocks,  brought 
from  the  Val  de  Ferret  by  a  former  glacier,  and  must  once  have  been  a 
medial  moraine,  which,  after  the  melting  of  the  ice  which  carried  it  along, 
was  stranded  on  this  promontory.  At  one  time  a  number  of  former  mo- 
raines of  this  kind  were  found  at  various  spots  in  Switzerland ;  but  the 
harder  rocks  having  been  much  used  as  stones  for  building,  these  remains 
are  disappearing  more  and  more  every  day. 

The  question  which  has  given  rise  to  the  most  animated  discussions 
among  geologists  is  the  problem  how  the  moraines  of  the  Alpine  glaciers, 
and  the  great  stones  which  in  former  times  they  drifted  along  in  their 
course,  managed  to  cross  the  great  lakes  of  Switzerland  and  Lombardy. 
Thus  the  town  of  Lucerne  is  built  upon  the  debris  which  was  once  borne 


218 


THE  EARTH. 


along  on  the  immense  glacier  of  the  Reuss,  which,  descending  from  the  St. 
Gothard,  crossed  over  the  depths  of  the  Lac  des  Quatre  Cantons.    In  like 


Fig.  72.  Ancient  Moraine  falling  down. 

manner,  to  the  south  of  the  Lake  of  Garda,  the  hills  of  Solferino,  Cavriana,' 
and  San  Martino,  on  which  was  fought  the  terrible  battle  of  1859,  are  noth- 
ing more  than  heaps  of  stones,  which  once  served  as  an  advanced  guard 
to  glaciers.*  Added  to  this,  erratic  masses  of  stone,  or  boulders  proceed- 
ing from  the  Alps — as  is  shown  by  the  crystalline  nature  of  these  rocks 
— are  found  on  the  eastern  slopes  of  the  Jura ;  they  are  seen  at  various 
heights,  and  even  at  as  much  as  3300  feet  above  the  level  of  the  sea. 
Among  these  blocks — a  few  of  which  are  from  5000  to  6000  cubic  yards 
in  bulk — there  are  some  which  the  savants^  from  a  study  of  their  miner- 
alogical  composition,  can  clearly  specify  as  having  come  down  from  cer- 
tain mountains  in  the  groups  of  the  Finsteraarhoru,  Monte  Rosa,  and 
Mont  Blanc.  By  what  means  have  these  blocks  of  rock  been  able  to  ac- 
complish their  journey  before  they  became  stranded  on  the  mountain  sides 
of  the  Jura?  Was  the  Lake  of  Geneva  much  more  elevated  at  a  former 
epoch  than  it  is  at  present,  and  did  the  enormous  masses  of  ice,  which  fell 
into  it  from  the  glacier  of  the  Rhone  and  ultimately  floated  to  the  oppo- 
site bank,  inclose  blocks  of  rocks  and  stones  like  the  icebergs  of  the  noith- 
ei-n  seas?  Or  was  it  the  fact  that  the  glaciers  filled  with  their  masses 
the  deep  cavities  of  all  the  lakes  of  Switzerland  and  Lombardy,  and,  like 
the  Rhone,  which  continues  its  course  after  having  so  widely  expanded 
in  order  to  form  the  Lake  of  Geneva,  crossed  over  these  lakes,  and  flowed 
out  far  and  wide  into  the  plains  of  France  and  Italy  ?  This  last  hypothe- 
sis appears  probable,  for  on  the  sides  of  the  mountains  which  overhang 
these  lakes,  and  especially  round  the  lakes  Maggiore,  Como,  and  Garda, 
the  ancient  stnm  of  the  glaciers  are  still  to  be  perceived,  and  some  of  the 
insular  rocks  retain  that  tnoutonneed  appearance  which  bears  witness  to 
the  fact  that  the  ice  had  passed  over  them.f  Added  to  this,  the  protec- 
tion afforded  by  the  masses  of  ice  which  filled  them  up  have  probably 
been  the  cause  why  the  deep  cavities  of  the  lakes  were  not  choked  up  by 
the  debris  which  fell  from  the  bi'oken  ridges  above  on  to  J;he  moving  bed 
of  the  glacier.    Some  geologists  have  put  forward  the  hypothesis  that  the 

*  Martins  and  Gastaldi.     Murchison,  Journal  of  the  Geographical  Society,  18G4. 
t  Martins,  Bibliotheque  de  Geneve,  July,  1866. 


ERRATIC  BLOCKS  AND  BOULDERS.  219 

beds  of  the  Alpine  lakes  were  hollowed  out  entirely  by  the  Alpine  gla- 
ciei-s.  This  view,  so  ably  advocated  by  Professor  Ramsay,  the  director 
of  the  geological  survey  of  England  and  Wales,  has  lately  received  great 
support  from  Professor  Newberry's  investigation  of  the  lake-system  of 
North  America. 

However  this  may  be,  the  enormous  exftnt  of  the  old  ice-rivers  of  Switz- 
erland is  a  fact  henceforth  unquestionable.  Nor  can  it  be  doubted  that 
the  same  thing  was  the  case  in  all  the  rest  of  Europe.  From  one  extremi- 
ty of  the  chain  to  the  other  the  Pyrenees  present  unequivocal  evidences  of 
the  glacial  epoch,  and  in  some  valleys — those,  for  instance,  of  Oo  and  Ar- 
gelez — the  frontal  moraines  are  still  almost  as  distinctly  visible  as  if  the 
ancient  glacier  had  melted  only  the  day  before.  In  like  manner,  to  the 
west  of  Vosges,  the  natural  banks  of  sand,  gravel,  and  heaped-up  rocks 
which  pen  in  the  water  of  the  little  lakes  of  Gerardmer,  Longemer,  and 
Frondome,  are  nothing  else  but  old  moraines.  Similar  phenomena  are 
found  in  the  mountains  of  other  countries — Wales,  Scotland,  and  Ireland, 
in  the  Carpathians  and  the  Riesengebirge. 

Another  proof  of  the  enormous  development  of  the  ice  system  during  a 
comparatively  recent  epoch  may  be  derived  from  the  dispersion  of  the  er- 
ratic rocks  or  boulders,  which  are  found  in  such  great  numbers  in  the 
countries  of  the  north  of  Europe.  It  is  now  beyond  all  question  that  the 
numerous  lines  of  rocks  which  are  found  here  and  there  all  over  Northeiii 
Russia  have  proceeded  from  the  granite  mountains  of  Scandinavia.  When 
an  immense  sea  extended  over  Finland,  between  the  Baltic  and  the  Polar 
Ocean,  the  blocks  of  ice  which  fell  into  the  water  that  washed  the  base  of 
the  Scandinavian  mountains  drifted  away  in  flotillas  toward  the  south- 
east to  the  shores  of  the  continent  opposite.  The  prominent  angles  of  the 
granite  blocks  contained  in  the  masses  of  floating  ice  have  traced  out  long 
furrows  over  all  the  points  and  projections  of  the  rocks  in  Finland,  which 
was  then  only  a  marine  shoal.  M.  Nordenskiold  has  ascertained  that  al- 
most all  these  lines  of  erosion  tend  from  the  northwest  to  the  southeast, 
and  that  all  the  rocks  with  which  the  icebergs  have  come  into  contact  are 
polished  on  the  side  which  faces  toward  Scandinavia,  Avhile  on  the  other 
side  they  have  in  every-  case  retained  their  uneven  suifaces,  their  projec- 
tions, and  their  clefts.  With  regard  to  the  boulders  themselves,  they  are 
all  more  rounded  by  friction  the  more  distant  they  are  from  the  Swedish 
mountains  of  which  they  once  formed  a  part.  All  the  phenomena  which 
once  were  effected  on  so  vast  a  scale  round  the  shores  of  the  Baltic  are, 
however,  still  taking  place.  During  the  winter  of  1862-3,  immense  mass- 
es of  ice,  coming  from  Finland,  were  cast  upon  the  southern  coast  of  the 
gulf,  and  thrown  up  on  the  land  to  a  distance  of  more  than  300  yards  from 
the  shore,  and  to  a  height  of  30  feet  above  the  level  of  the  sea.  The  ice, 
which  was  40  to  50  feet  deep,  overwhelmed  many  dwellings  and  whole 
forests ;  in  the  latter  large  quantities  of  stones  were  subsequently  found, 
which  the  ice  left  bcliind  when  it  thawed.* 

*  Keyserling  and  Von  Baer,  Bull,  de  I' Acad,  de  St.  P€ter^wurg,\ol.  v.,  April,  1863. 


220 


THE  EARTH. 


These  boulders  are  scattered  in  considerable  numbers  over  the  toiindras 
and  plains  of  Northern  Russia;  they  are  also  found  in  Prussia  and  Poland 
as  far  as  the  slopes  of  the  Carpathian  Mountains.  They  are  seen  round 
the  North  Sea,  on  the  coasts  of  Friesland,  England,  and  Scotland.  The 
investigations  also  of  M.  Bohtlingk  have  shown  that  erratic  rocks,  or 
boulders,  have  made  their  wayfborne  on  masses  of  ice,  from  the  fiords  of 
Lapland  toward  the  Northern  Ocean.  Thus  the  great  island  of  the  Nor- 
wegian mountains  was  once  a  centre  of  dispersion  from  which  the  rocks, 
instead  of  merely  rolling  to  the  bottom  of  the  slopes,  were  distributed  in 
various  directions  over  the  immense  space  included  between  the  British 
Isles,  Spitzbergen,  the  Ural  Mountains,  Valdai,  and  the  Carpathians. 
Strange  to  tell,  numbers  of  these  Scandinavian  rocks,  thus  stranded  be- 
yond the  sea,  are  still  overgrown  with  lichens  and  other  plants  belonging 
to  Norwegian  families.  They  might  be  compared  to  colonies  of  poor  ship- 
wrecked creatures  cast  upon  a  foreign  shore.* 

In  the  gentle  undulating  plains  of  North  America,  boulders  and  other 
debris  brought  by  floating  ice  are  likewise  found  scattered  over  wide  tracts 
of  country.  The  vegetable  soil  of  some  of  the  most  fertile  districts,  such 
as  Illinois,  Indiana,  and  Michigan,  is  in  gi'eat  part  composed  of  earth 
brought  by  stranded  icebergs,  and  here  and  there  may  be  found  in  the 
mass  of  this  transported  soil  enormous  blocks  of  granite  which  one  belong- 
ed to  the  Laurentian  Mountains,  or  to  some  other  rocky  chain  in  Canada. 

Thus  the  effects  of  the  ancient  glacial  period  are  still  perfectly  visible 
in  the  plains  of  the  New,  as  well  as  of  the 
Old  World.  These  are,  in  fact,  the  spots 
where  we  should  expect  to  find  the  traces 
of  former  glaciers ;  but  even  warmer  coun- 
tries exhibit  on  their  mountain  sides  and 
in  their  goi'ges  most  distinct  traces  of  an- 
cient ice-currents.  Thus  Hooker,  the  bot- 
anist, noticed  at  the  base  of  the  Himalayas 
the  remains  of  old  moraines  forming  actual 
barriers  across  the  valleys ;  in  Syria,  too, 
he  felt  justified  in  stating  that  the  cele- 
brated cedars  of  Lebanon  grow  on  masses 
of  debris  of  the  same  nature.  At  the  foot 
of  the  Sierra  Nevada,  of  Santa-Marta,  on 
the  coast  of  Columbia,  where  the  mean 
temperature  is  80°  (Fahr.),  masses  o^ debris 
are  also  found  that  the  ice,  which  then  de- 
scended 1300  feet  lower  than  it  now  does, 

pushed  in  front  of  it  to  the  very  sea.      Last-   Fig.  T3.  Ancient  Glacier  of  Yan^ma,  in  the 
ly,   Agassiz    has    likewise    recognized    the  Himalayas ;  after  Hooker. 

track  of  ancient  glaciers  in  Brazil,  not  far  from  Rio  de  Janeiro,  and  even 

under  the  equator,  at  the  mouth  of  the  Amazon.     In  fact,  the  reef  of  Per- 

*  Chri.st,  Alpenjlora,  in  vol.  ii.  of  the  Schweizer  Alpen-Club. 


ALTERNATION  OF  GLACIAL  PERIODS.  221 

nainbuco  and  the  whole  of  the  adjacent  coast  are  nothing  but  a  long  se- 
ries of  moraiyies  beaten  and  consolidated  by  the  waves.  Every  region  of 
the  globe  has  therefore  had  its  glacial  period.  But  was  this  period  coin- 
cident in  all  the  various  regions  of  the  globe,  or  did  it  fluctuate  from  one 
hemisphere  to  the  other,  prevailing  at  one  time  on  the  north,  and  at  anoth- 
er time  south  of  the  equator?  We  can  not  tell;  it  is,  however,  probable 
that  a  rhythmical  fluctuation  of  temperature  took  place  during  the  lapse 
oi  centuries  from  one  pole  to  the  other,  and  that  consequently  the  glacial 
periods  have  alternated  in  Europe  and  Africa,  and  in  North  and  South 
America.  According  to  Hochstetter,  New  Zealand  and  Patagonia,  where 
the  ice  descends  so  low,  are  now  passing  through  their  glacial  period. 
There  are,  however,  hypotheses  in  abundance  in  respect  to  the  extension 
of  the  ancient  glaciers,  and  on  this  point  generally  geologists  are  still 
very  far  from  agreeing  on  any  common  theory. 


222  ^^^  EARTH. 


CHAPTER  XXXVn. 

SECONDAET   PART  TAKEN   BY  GLACIERS   IN   THE    CIRCULATION  OF  WATER. — 

MOUNTAIN  FLOOD-WATERS. ABSORPTION   OF  RAIN  AND  MELTED  SNOW  BY 

THE    EARTH,  PEAT-MOSSES,  AND   ROCKS. — SPRINGS   AND  THEIR  NYMPHS.' 

Except  in  the  polar  regions,  only  a  very  small  portion  of  the  atmos- 
pheric waters  become  fixed  in  glaciers,  to  remain  lying  on  the  mountain 
sides  for  years  or  even  centuries.  The  proportion  of  water  which  falls 
from  the  clouds  in  a  liquid  form  is  much  more  considerable,  and  conse- 
quently plays  comparatively  a  much  more  important  part  in  the  economy 
of  the  globe.  Rain  and  melted  snow,  being  incomparably  more  active 
than  ice  in  its  circulatory  movement,  either  flow  away  at  once  on  the  sur- 
face as  rivers,  or  disappear  into  the  depths  of  the  rocks,  whence  they  will 
gush  out  at  some  distant  spot  in  the  /orm  of  springs,  or  will  perhaps  con- 
tinue their  subterranean  course  as  far  as  the  abysses  of  the  ocean. 

In  mountain  gorges  where  the  ground  or  bare  rock  will  not  allow  the 
rain  and  snow-water  to  sink  in,  the  stream  runs  down  rapidly  toward  the 
plain,  carrying  with  it  along  the  bottom  of  its  bed  the  debris  which  is 
washed  away  from  the  slopes.  After  an  exceptionally  heavy  rainfall,  it  is 
often  difficult  to  form  any  clear  distinction  between  one  of  these  tempo- 
rary torrents,  a  fall  of  rubbish  and  mud,  or  an  aval&nche.  In  this  case, 
the  masses  of  half-melted  snow,  mixed  with  liquid  mud,  are  hurried  on  by 
their  own  weight,  and  slide  down  the  slopes,  driving  before  them  heaps  of 
loose  stones  and  rubbish.  The  whole  semi-liquid  body  very  soon  sinks 
down  into  the  ravine  which  forms  the  channel  of  descent.  The  water  and 
dirty  snow  are  mingled  in  one  dark  and  miry  mass,  in  the  midst  of  which 
rocks  and  stones  bound  about  as  they  roll  along ;  in  this  moving  chaos 
the  fragments  of  debris  are  constantly  coming  into  collision  with  a  crash 
that  shakes  the  rocky  banks,  while  the  flow  of  the  torrent  tears  away  their 
base.  In  many  places  these  enormous  masses  totter  in  their  turn,  and 
soon  participate  in  the  immense  downfall.  A  noise  like  thunder  is  the 
harbinger  of  the  avalanche,  and  announces  it  from  afar  to  any  persons  that 
may  happen  to  be  in  its  line ;  but  these  phenomena,  which  are  at  the  same 
time  both  earthfalls  and  avalanches,  last  but  for  a  very  few  instants.  The 
torrent  carries  away  with  it  and  tosses  about  like  pebbles  enormous  rocks 
thirty  feet  square,  and  when  it  has  passed  away  it  leaves  nothing  behind 
but  thick  layers  of  mud. 

These  semi-liquid  avalanches  are,  fortunately,  not  very  frequent,  at  least 
in  Europe  ;  but  all  the  heavy  i-ains  which  fall  on  the  mountain  slopes,  and 
even  on  the  more  or  less  inclined  soil  of  the  low-lying  lands,  cause  the  for- 
mation of  torrents  and  temporary  streams.  These  constitute  flood-waters. 
Dashing  down  all  the  defiles,  ravines,  and  depressions  of  the  ground,  they 


ABSORPTION  OF  MOISTURE.  223 

wash  away  all  the  debris  which  is  accumulated  in  them,  clearing  off  the 
vegetable  soil,  plants,  and  brushwood,  and  plowing  up  their  beds  when  the 
rock  is  not  of  too  compact  a  character;  when  they  reach  the  river  flowing 
through  the  plain,  they  pour  into  it  masses  of  mud  and  heaps  of  pebbles 
carried  away  from  the  hills.  They  are,  in  fact,  real  geological  agents,  and 
their  operations  during  a  day,  or  perhaps  only  an  hour,  contribute  no  mean 
share  in  the  modification  of  the  earth's  surface. 

If  all  soils  were  absolutely  impervious,  there  would  be  no  springs,  and 
the  whole  of  the  liquid  mass  furaished  by  rain  and  snow  would  flow  away 
over  the  surface  of  the  ground  like  the  torrents  and  flood-waters  of  the 
mountains.  The  greater  part,  however,  of  the  water  which  falls  upon  the 
ground  sinks  in  the  first  place  into  the  depths  of  the  earth.  There  it  be- 
comes more  or  less  perfectly  purified  from  the  foreign  bodies  with  which 
it  was  charged,  gradually  rising  to  the  temperature  of  the  strata  through 
which  it  passes,  and  becoming  impregnated  with  the  soluble  salts  which  it 
meets  with.  Ultimately,  when  the  water,  in  sinking  down,  encounters  im- 
pervious beds,  it  can  penetrate  no  farther,  and,  flowing  laterally  to  the  out- 
crop of  the  beds,  makes  its  escape  in  the  form  of  springs. 

The  absorption  of  the  rain  and  melted  snow  takes  place  in  various  ways, 
according  to  the  nature  of  the  soil.  Ordinary  vegetable  earth  only  allows 
the  w^ater  to  penetrate  to  a  very  slight  depth,  especially  when  the  rain 
falls  in  showers  and  the  slope  of  the  ground  is  favorable  for  drainage.  As 
mould  is  capable  of  absoi'bing  a  very  large  quantity — indeed,  more  than 
lialf  its  own  weight,  it  prevents  the  strata  beneath  from  receiving  its  due 
share  of  moisture,  retaining  almost  the  whole  of  it  for  the  use  of  the  vege- 
tation which  it  nourishes.  In  fact,  it  requires  an  altogether  exceptional 
rainfall  to  saturate  any  ordinary  arable  soil  to  the  extent  of  a  yard  below 
the  surface.  Water  passes  with  much  more  facility  through  sandy  and 
gravelly  beds;  but  compact  loams  and  clay  will  not  allow  it  to  penetrate 
through  them,  retaining  it  in  the  form  of  pools  or  ponds  on  the  surface  of 
the  ground. 

The  action  of  vegetation  is  not  confined  merely  to  imbibing  the  water 
falling  from  the  clouds;  it  often,  also,  assists  the  superabundant  moisture 
in  penetrating  the  interior  of  the  ground.  Trees,  after  they  have  received 
the  water  upon  their  foliage,  let  it  trickle  down  drop  by  drop  on  the 
gradually  softened  earth,  and  thus  facilitate  the  gentle  permeation  of  the 
moisture  into  the  substratum ;  another  part  of  the  rain-water,  running 
down  the  trunk  and  along  the  roots,  at  once  finds  its  way  to  the  lower 
strata.  On  mountain  slopes,  the  mosses  and  the  freshly-growing  carpet 
of  Alpine  plants  swell  like  sponges  when  they  are  watered  with  rain  or 
melted  snow,  and  retain  the  moisture  in  the  interstices  of  their  leaves  and 
stalks  until  the  vegetable  mass  is  thoroughly  saturated  and  the  liquid 
surplus  flows  away.  Peat-mosses  especially  absorb  a  very  considerable 
quantity  of  water,  and  form  great  feeding  reservoirs  for  the  springs  which 
gush  out  at  a  lower  level.  The  immense  fields  of  peat  which  cover  hun- 
dreds and  thousands  of  acres  on  the  mountain  slopes  of  Ireland  and  Scot- 


224  THE  EARTH. 

land  may,  notwithstanding  their  elevation  and  inclined  position,  be  con- 
sidered as  actual  lacustrine  basins  containing  millions  of  tons  of  water 
dispersed  among  their  innumerable  leaflets.*  The  supei'abundant  water 
of  these  tracts  of  peat-mosses  issues  forth  in  springs  in  the  plains  below. 

Rocks,  like  vegetable  earth,  also  absorb  water  in  greater  or  less  quanti- 
ties, according  to  their  fissures  and  the  density  of  their  particles.  If  the 
soil  is  formed  of  volcanic  scoriae,  or  porous  beds  of  pebbles,  gravel,  or 
sand,  the  water  rapidly  descends  toward  the  underlying  strata.  Some  of 
the  harder  rocks,  especially  certain  kinds  of  granite,  absorb  but  a  very 
small  quantity  of  water,  on  account  of  the  small  number  of  their  clefts ; 
others,  on  the  contrary,  as  most  of  the  calcareous  masses,  imbibe  every 
drop  of  water  which  falls  on  their  surface.  There  are  some  rocks  which 
have  their  layers  broken  and  cracked  to  such  an  extent  that  they  resem- 
ble enormous  walls  of  rubble- work ;  the  rain  instantly  disappears  on  them 
as  if  it  had  fallen  into  a  sieve.  But  the  greater  part  of  the  calcareous 
rocks  belonging  to  various  geological  periods  are  formed  of  thick  and  reg- 
ular strata,  cleft  at  intervals  by  long  vertical  crevices.  Below  the  sur- 
face-beds, perhaps,  are  layers  of  soft  marl,  which  the  water  penetrates  with 
difiiculty,  although  it  can  soften  and  carry  away  its  particles.  Here  are 
formed,  rill  by  rill,  the  subterranean  rivulets  which  ultimately  spread  all 
over  the  substratum  of  marl,  following  the  general  slope  of  the  bed. 
After  a  more  or  less  considerable  lapse  of  time,  the  stratum  of  marl  ulti- 
mately becomes  saturated,  and  the  water  then  flows  out  through  caverns 
which  are  variously  modified  by  subsidences — faults  in  the  strata  and  the 
perpetual  action  of  the  streams.  The  springs  which  proceed  from  calca- 
reous rocks  of  this  nature  are  in  general  the  most  abundant,  owing  to  the 
length  of  their  subterranean  course.  The  water  which  falls  on  vast  areas 
on  the  surface  of  plateaux  is  ultimately  united  in  one  bed.  A  liquid  mass 
of  this  kind,  which  springs  up  suddenly  into  sight,  just  as  if  it  merely  is- 
sued from  the  soil,  drains  perhaps  an  extent  of  country  of  many  hundreds 
or  thousands  of  square  miles. 

Thus,  according  to  the  nature  of  the  rock  on  which  the  rain  falls,  the 
latter  finds  its  way  again  to  the  surface,  either  at  a  considerable  distance 
from  the  spot  where  it  fell,  or  else  springs  out  in  little  rivulets  immedi- 
ately below  the  place  where  its  drops  were  first  gathered.  On  a  great 
many  mountains  we  are  surprised  to  meet  with  springs  gushing  out  at  a 
few  yards  from  the  summit.  These  jets  have,  indeed,  often  been  consid- 
ered as  the  evidence  of  some  miraculous  intervention.  Among  others, 
we  may  mention  the  "  Sorcerers'  Spring,"  which  gushes  out  on  one  of  the 
highest  points  of  the  Brocken,  the  culminating  peak  in  the  Hartz  Moun- 
tains. The  position  of  this  spring  is,  in  reality,  1 9  feet  lower  than  the 
highest  part  of  the  terminal  plateau,  and  it  has  been  calculated  that  if  it 
served  as  the  drainage  outlet  for  all  the  rain  falling  on  th6  top  of  the 
mountain,  it  might  well  supply  rather  more  than  a  gallon  and  a  half  a 
minute.  Now,  as  a  matter  of  fact,  it  scarcely  furnishes  a  third  of  this 
quantity.  It  is,  however,  but  very  rarely  that  it  altogether  fails,  and  in- 
*  Vide  the  chapter  on  "Lakes." 


SPRLYOS  AND  THEIR  NYMPHS.  29'5 

stances  of  this  have  been  seldom  recorded.*  In  the  principal  islet  of  the 
Chausey  group,  which  is  only  770  yai'ds  long  by  275  broad,  there  is  also 
a  constant  spring,  and  the  question  is  whether  the  rain  which  falls  on  this 
rock  is  sufficient  to  supply  the  fountain,  or  whether  it  is  fed  by  the  filtra- 
tion o^  water  from  the  neighboring  continent.f  The  valleys  which  lie  at 
the  mountain  foot,  or  even  the  plains  that  border  on  less  important  heights, 
are,  however,  the  principal  spots  where  springs  gush  forth  in  the  greatest 
number.  Springs  form  a  special  charm  in  those  unassuming  landscapes 
in  which  nature  develops  all  its  beauties  within  a  restricted  space.  Stand- 
ing on  the  bank  of  some  little  brook  which  bubbles  as  it  glides  along, 
lending,  as  it  were,  to  nature  an  almost  articulate  voice  of  kindness,  the 
eye  embraces  a  graceful  ensemble  which  can  hardly  fail  both  to  charm  and 
soothe.  Almost  involuntarily  a  feeling  seems  awakened  within  us  of  liv- 
ing sympathy  with  the  objects  around,  all  of  which  appear  as  if  made  to 
harmonize  with  man's  condition.  The  spectator  feels  softened,  and  is  not 
oppressed  and  bewildered  with  admiration  as  when  surveying  a  mighty 
cataract,  a  glacier,  or  the  waves  of  the  sea.  Besides,  can  we  look  upon 
even  a  tiny  spring  without  an  instinctive  feeling  being  stiiTed  up  within 
us  that  in  it  we  see  the  real  fountain-head  of  all  civilization  ?  In  this  lit- 
tle corner  of  the  earth  every  thing  is  arranged  as  heart  could  wish  for  the 
needs  of  the  firet  husbandman.  There  are  overhanging  trees  to  shade 
him,  a  hillock  to  shelter  him  from  the  rude  wind,  pure  water  for  his  gar- 
den, and  stones  to  build  his  hut.  What  more  could  he  require  ere  he 
commenced  those  great  labors  in  the  improvement  of  the  earth  which 
have  made  us,  his  descendants,  what  we  now  are  ? 

If  SL  blase  inhabitant  of  our  cities  is  unable  to  contemplate  a  spring  with- 
out some  degree  of  poetic  feeling,  how  much  more  vivid  must  this  senti- 
ment have  been  among  our  ancestors,  who  lived  in  the  very  bosom  of  na- 
ture! Some  ancient  nations,  indeed,  woi-shiped  fountains  as  if  they  Avere 
divinities.  The  Greeks,  who  knew  so  well  how  to  ascribe  even  to  inani- 
mate objects  a  fellow-feeling  both  in  their  passions  and  in  their  joys,  have 
given  a  personality  to  each  of  their  fountains,  transforming  them  into  some 
graceful  nymph  or  some  glorious  demigod.  Travelers  can  not  refrain 
from  astonishment  when  they  perceive  the  humble  springs  of  Ilippocrene 
or  Castalia,  and  the  mere  rivulets  of  the  Scamander,  the  Alpheus,  the 
Ilyssus,  or  the  Eurotas,  on  which  the  poets  of  Greece  have  conferred  such 
imperishable  glory.  What !  they  cry,  are  these  miserable  streams  the 
fountains  and  rivers  that  the  Hellenes  honored  with  statues  and  temples? 
Are  these  slender  crystal  rivulets,  gliding  among  the  rocks,  the  objects 
which  were  invoked  as  patrons  for  powerful  cities,  and  were  sung  of  in 
their  poetry  in  almost  divine  rhapsodies  ?  These  springs  seem  very  trifling 
things  to  us — to  us  barbarians  of  the  North,  who  only  know  how  to  appre- 
ciate the  colossal,  and  reserve  all  our  admiration  for  great  rivers,  such  as 
the  Mississippi  or  the  Amazon.     Yet  who  can  ever  adequately  describe 

*  Von  Kluden,  Handhuch  tier  Krdhunde. 
t  Audoin  aud  Milne-Edwards,  Le  Littoral  de  la  France. 
P 


226  THE  EARTH. 

the  ineffable  beauty  of  the  smallest  spring,  no  matter  whether  it  flow  be- 
tween two  flowery  banks  under  the  mystenous  shade  of  overhanging 
trees,  or  slowly  trickles  from  a  dark  grotto  under  white  chalky  rocks,  or 
jet  up  in  glittering  pearls  from  a  pebbly  bed,  dancing  the  grains  of  sand 
on  its  tremulous  drops — each  fountain  has  its  own  special  character  of 
o-race  or  stern  beauty.  One  is  the  charming  Acis,  escaping  from  the  lava 
rocks  under  which  the  Cyclops  wished  to  overwhelm  him ;  another  is  the 
nymph  Arethusa,  swimming  under  the  sea  so  as  not  to  mingle  her  blue 
water  with  the  troubled  wave;  another,  again, is  the  virgin  Cyane, bath- 
ing the  flowers  which  she  once  gathered  to  weave  a  coronet  for  Proserpine. 

It  is  easy  to  understand  the  veneration  which  is  felt  for  springs  by  the 
inhabitants  of  tropical  countries,  who  live  on  an  arid  soil  and  under  a 
burning  sky.  Even  on  the  borders  of  deserts  and  on  the  oases,  water- 
sources  are  rare,  and  their  inestimable  value  is  all  the  more  appreciated. 
That  slender  spring,  which  trickles  from  the  cleft  of  some  rock,  is  the 
agent  which  nourishes  the  grass,  the  grain,  and  the  fruit  which  are  neces- 
sary for  the  subsistence  of  a  whole  tribe.  Should  its  water  happen  to 
fail,  the  whole  population  is  obliged  to  migrate  immediately,  or  else  die 
of  hunger  or  thirst.  The  inhabitant,  therefore,  of  the  oasis  professes  a 
kind  of  worship  for  the  bounteous  element  which  is  to  him  the  source  of 
life.  In  climates  more  favored  iij  their  rainfall,  man's  love  for  water- 
springs  naturally  lessens  in  proportion  to  their  abundance;  but  some 
relics  of  this  sentiment  may  be  found  in  the  hearts  of  every  nation — those 
even  that  inhabit  the  best-watered  countries.  This  instinctive  veneration 
for  rising  springs  is  probably  the  cause  of  the  Swiss  mountaineers  not  con- 
sidering the  torrents  of  muddy  water  issuing  from  the  terminal  arch  of  a 
glacier  as  the  real  source  of  rivers ;  this  honor  they  award  to  the  little 
unassuming  rills  which  trickle  out  at  the  foot  of  the  rocks.  In  their  idea 
the  true  Rhone  is  not  the  furious  water-course  which  dashes  out  of  the 
glacier;  it  is  a  slightly  thermal  spring  which  glides  among  the  rocks 
some  hundreds  of  yards  below  the  frontal  moraine.  TMs  spring-water, 
which — differing  from  the  ice-torrent — never  fails  in  winter,  is  ferruginous 
in  its  nature,  and  stains  the  snows  in  its  bed  with  a  reddish  hue ;  hence, 
they  say,  the  name  of  Rhone  {Rothen).* 

Neither  the  charm  nor  .even  the  utility  of  springs  are  the  sole  causes 
why  they  are  so  much  beloved ;  the  mystery  of  their  origin  also  promotes 
this  feeling.  We  are  fond  of  inquiring  as  to  the  origin  of  these  jets  of 
pure  water,  and  of  tracing  out  the  paths  that  they  have  followed  through 
the  bowels  of  the  earth  before  they  emerged  into  the  light  of  day.  From 
what  mountain  summit  has  this  charming  fountain  nymph  descended,  and 
in  what  grotto  has  she  made  her  abode?  Such  are  the  inquiries  which 
the  uninitiated  might  make  at  the  sight  of  a  spring — inquiries,  too,  which 
savants  are  yet  far  from  having  answered.  What  a  multiplicity  of  studies 
and  investigations  have  yet  to  be  made  ere  we  can  trace  out,  without  fear 
of  error,  the  circuit  accomplished  by  a  drop  of  water  through  the  rocks, 
rivers,  and  clouds ! 

*  H.  de  Saussure,  Voyaijes  dans  les  Aljies,  vol.  iii. 


VABIATION  IN  SPRIN08.  £27 


CHAPTER  XXXVm. 

VARIATION  IN  THK  DISCHARGE  OF  SPRINGS.  —  E8TAVELLES.  EQUALIZA- 
TION OF  THE  SUPPLY  IN  SPRINGS  WITH  DEEP  SOURCES. — INTERMITTENT 
SPRINGS. 

It  may  be  stated  generally  that  the  discharge  of  a  spring  varies  accord- 
ing to  the  quantity  of  rain.  After  an  extraordinary  rainfall,  all  springs 
have  a  tendency  to  increase  and  overflow,  with  the  exception  of  those 
which,  owing  to  the  form  of  their  subterranean  bed,  are  unable  to  yield 
any  more  considerable  body  of  water.  It  sometimes  happens  that,  during 
exceptionally  rainy  seasons,  springs  gush  out  from  rock-crevices  which  are 
almost  always  dry,  and  form  temporary  rivulets.  These  are  called /bw- 
taines  de  disette  (scarcity  STpr'mgs),  fonts  famineuses  (famine  springs),  or 
bramafans  (hunger  cries).  The  farmers  very  justly  look  upon  their  ap- 
pearance as  the  formidable  foreboding  of  a  year  much  too  wet  for  their 
crops. 

With  regard  to  springs  of  a  permanent  character,  there  are  a  consider- 
able number  which,  issuing  from  a  rock  which  is  split  and  rent  in  every 
direction,  form  supplementary  orifices  after  any  great  amount  of  rain. 
Among  the  mountains  we  may  often  notice  that  walls  of  rock,  which  in 
ordinary  seasons  have  little  rivulets  of  water  trickling  along  their  base, 
will,  in  a  rainy  season,  be  enlivened  by  cascades  dashing  down  from  vari- 
ous heights  of  the  jointed  face.  In  gorges,  and  on  gently  inclined  slopes, 
phenomena  of  the  same  nature  are  developed ;  but  in  some  cases  it  is  dif- 
ficult to  recognize  the  intimate  connection  which  exists  between  the  va- 
rious springs  which  rise  at  different  intervals  of  space  along  the  same  val- 
ley. In  fact,  at  first  sight,  one  can  hardly  understand  how  a  temporary 
flow  of  water,  gushing  out  a  mile  or  two  above  a  constant  spring,  can 
nevertheless  be  connected  with  the  same  subterranean  stream,  and  so  form 
a  kind  of  waste-valve  for  the  lower  orifice.  In  Languedoc  these  supple- 
mentary flows  are  called  estavelles,  a  term  which  has  been  recently  intro- 
duced by  M.Fournet  into  scientific  language. 

The  calcareous  slopes  of  the  Jura  present  some  remarkable  instances  of 
estavelles,  among  which  those  in  the  environs  of  Porrentruy  are  specially 
worthy  of  notice.  Four  copious  springs,  which  rise  in  the  town  itself,  are 
the  outlets  of  a  subterranean  water-course  fed  by  the  mountains  rising  to 
the  southwest.  Owing  to  certain  depressions  in  the  ground,  and  to  the 
sound  of  underground  currents  which  are  here  and  there  heard,  the  con- 
cealed stream  may  be  easily  traced  as  far  as  the  well,  or  creux  (hollow),  of 
Gena,  about  two  miles  and  a  half  from  the  town,  situated  at  the  foot  of  a 
hill.     In  a  general  way,  all  that  can  be  seen  at  the  bottom  of  the  hole  is  a 


22S  THE  EAMTH. 

little  Stream  of  water  making  its  way  down  toward  the  valley ;  but  after 
heavy  rain  or  a  rapid  thaw  of  snow,  the  water  bursts  up  with  a  roaring 
noise  from  the  subterranean  cavities,  and,  pouring  furiously  into  the 
meadows,  spreads  over  the  surface  of  the  ground,  and  ultimately  runs 
down  to  the  town  of  Porrentruy.  Beyond  this  estavelle,  where  several 
subterranean  water-courses  unite,  the  slope  of  the  valley  becomes  more 
and  more  steep,  and  other  wells  or  crevx  of  the  same  kind  are  seen,  from 
which  the  ovei-flowing  water  of  the  stream  beneath  temporarily  issues. 


Fig.  74.  "  Estavelles"  of  Porrentruy. 


Higher  up  still,  the  escarped  ravine  of  Rochedor  commences,  where,  dur- 
ing the  whole  year,  the  rivulet,  running  sometimes  below  and  sometimes 
above  the  surface  of  the  ground,  passes  through  a  series  of  chasms.  At 
one  place  it  springs  up  suddenly  to  the  top  of  the  rocks,  and  then  as  sud- 
denly disappears,  only  to  gush  forth  again  at  some  distance  down  the  ra- 
vine.* 

The  estaveUe  which  is  the  most  remarkable  in  France  for  its  abundant 
flow  of  water  during  the  rainy  seasons  is  situated,  like  the  springs  of  Por- 
rentruy, on  one  of  the  slopes  of  the  Jura.  It  is  called  the  Frais-Puits, 
and  rises  at  the  opening  of  a  little  valley  about  two  miles  and  a  half 
southeast  of  Vesoul.  In  ordinary  seasons,  a  spring  of  some  imijortance 
— that  of  Champdamoy — is  the  sole  outlet  for  all  the  rain  that  falls  in  the 
basin ;  but  when  the  subterraneous  caverns  ai"e  not  capacious  enough  to 
contain  the  whole  of  the  accumulated  liquid  mass,  it  flows  out  through 
the  orifice  at  Frais-Puits,  about  a  mile  and  a  quarter  above  Champdamoy. 
Sometimes,  indeed,  it  is  a  perfect  river  which  rushes  forth  from  this  abyss. 
It  inundates  the  meadows  of  Vesoul  over  an  extent  of  several  square 
miles,  and  floods  the  little  stream  in  the  valley,  influencing  even  the  Saone, 
which  receives  the  surplus  of  the  sudden  overflow.  The  Frais-Puits,  in 
conjunction  with  another  estaveUe,  a  tributary  of  the  Vesoul  stream,  has 
been  known  to  discharge  the  enormous  quantity  of  133  cubic  yards  of 
water  per  second,  equivalent  to  double  the  liquid  mass  of  the  Seine  at  its 
passage  under  the  bridges  of  Paris. 

We  thus  see  that  very  heavy  rain  has  the  eflfect  of  causing  springs  to 
gush  forth  in  spots  where,  in  a  general  way,  they  do  not  exist ;  but  we 
must  also  notice  that  every  precipitation  of  moisture,  even  the  most  in- 
considerable, has  its  proportional  influence  on  the  discharge  of  fountains 
*  Foumet,  Hudrographie  Souterraine, 


INTERMITTENT  SPRINGS.  229 

and  springs.  The  nightly  freezing  of  meltbg  snow,  the  increasing  intens- 
ity of  the  solar  rays,  the  intermittent  activity  of  the  phenomena  of  evap- 
oration taking  place  on  the  surface  of  the  soil — in  fact,  every  meteoric 
agency,  incessantly  tends  to  modify  the  action  of  water  springing  forth 
from  the  earth,  and  causes  it  to  change  every  day  and  even  every  hour. 
It  must,  however,  be  understood  that  springs  are  all  the  less  subject  to 
the  influence  of  the  rain,  sun,  and  wind  the  farther  the  subterranean 
streams  have  traveled,  and  the  deeper  they  have  descended  into  the  bow- 
els of  the  earth.  All  the  hinderances  which  the  percolating  water  is  sub- 
ject to  from  the  friction  of  its  liquid  particles  against  the  rocky  sides  of 
its  underground  course,  and  all  the  delays  which  it  is  forced  to  submit  to 
in  the  cavernous  lakes,  have  this  result — that  the  sudden  variations  which 
the  changes  of  the  seasons  cause  on  the  surface  of  the  ground  are  modified 
and  weakened  in  these  subterranean  beds.  Down  in  these  depths  the  sea- 
sons seem  to  blend  one  into  the  other,  and  their  effects  are  mutually  coun- 
terbalanced. Owing,  therefore,  to  the  long  and  winding  channels  which 
feed  them,  springs  are  able,  as  it  were,  to  regulate  themselves,  and  to  fur- 
nish, during  the  whole  year,  a  supply  of  water  which  varies  but  very 
slightly.  In  a  certain  number  of  thermal  springs  rising  from  fissures 
which  descend  to  a  very  considerable  depth  in  the  earth's  crust,  the  equi- 
librium of  the  liquid  mass  is  so  perfectly  established  that  any  variation 
answering  to  the  different  seasons  can  scarcely  be  perceived.  There  are, 
however,  certain  hot  wells,  replenished  from  reservoirs  with  which  they 
find  rapid  and  easy  means  of  communication,  which  show  a  great  variety 
in  the  amount  of  their  discharge,  according  to  the  quantity  of  rain  or 
snow  which  has  fallen  in  the  country.  Thus,  in  July,  1855,  after  a  long 
succession  of  stormy  weather,  the  hot  wells  at  Pfeffers,  in  Switzerland, 
sprung  out  in  such  abundance,  both  from  their  usual  source  and  also  from 
several  other  clefts  in  the  rock,  that  they  were  obliged  to  let  a  great  quan- 
tity of  the  water  flow  away  into  the  Tamina  without  making  any  use  of 
it.  The  following  year,  on  the  contrary,  the  hot  wells  received  such  an  in- 
considerable supply  that  it  was  feared  that  they  would  dry  up  altogether.* 
The  springs  which  cause  the  most  astonishment  are  those  which  for  a 
time  flow  plentifully,  and  then  all  at  once  cease  running,  but,  after  an  un- 
certain lapse  of  time,  again  make  their  appearance.  One  might  almost 
fancy  that  some  invisible  hand  alternately  opened  and  shut  the  secret 
flood-gate  which  gave  an  outlet  to  the  subterranean  stream.  The  cause 
for  this  phenomenon  of  intermission  is  easily  explained.  When  the  water 
brought  by  the  underground  stream  is  collected  in  a  capacious  cavity  in 
the  rock,  which  communicates  with  the  exterior  surface  through  a  siplioil- 
shaped  channel,  the  liquid  mass  gradually  rises  in  the  stone  reservoir  be- 
fore it  rushes  out  into  the  air.  It  is  necessary  that  the  reservoir  should 
^  be  filled  up  to  the  level  of  the  siphon,  in  order  that  the  latter  should  be 
primed,  and  that  the  water  should  flow  out  as  a  spring  into  the  external 
basin.  If  the  water  in  the  reservoir  is  not  replenished  with  sufiicient  ra- 
*  Otto  Volger,  Erd'.eben  in  der  Schweiz,  vol.  iii. 


230 


THE  EARTH. 


Fig.  75.  Section  of  an  Intermittent  Spring. 


pidity,  and  is  unable  to  keep  at  least  on  a  level  with  the  external  outlet, 
the  jet  of  water  will  immediately  cease,  and  can  not  recommence  until  the 
upper  part  of  the  liquid  mass  has  again  risen  up  to  the  highest  point  of 
the  siphon.  After  an  indefinite  period  of  repose,  the  spring  then  enters 
on  a  new  phase  of  activity. 

The  comparative  durations  of  the  intermissions  vary  according  to  the 
capacity  of  the  retaining  reservoir,  the  height  and  the  diameter  of  the 
siphon,  the  position  of  the  outlet-channel,  the  abundance  of  the  subterra- 
nean water,  and  the  force  of  the  evaporation.  Nevertheless,  the  action 
of  each  spring  is  incessantly  modified  by  the  frequency  or  scarcity  of  rain, 
and  the  jet  of  water  increases  or  shortens  the  duration  of  its  appearance. 
Occasionally  springs  which  are  generally  intermittent  are  recruited  by 
subterranean  channels  to  an  extent  sufficient  to  enable  them  to  flow  with- 
out interruption  for  weeks  or  whole  seasons.  At  other  times,  after  long 
periods  of  dryness,  the  spring  entirely  ceases  to  gush  out ;  and  the  visitor 
who,  on  the  faith  of  some  old  book,  stands  waiting,  watch  in  hand,  for  the 
predicted  appearance,  runs  a  good  chance  of  gazing  vainly  for  many  a 
long  hour  upon  the  dried-up  basin  of  the  fountain.  It  also  often  happens 
that  the  fall  of  rocks,  or  the  opening  of  fresh  clefts,  alters  the  course  of 
the  subterranean  stream  and  destroys  its  periodicity.  Thus  the  Buller- 
born,  a  spring  in  "Westphalia,  which  formerly  burst  out  of  the  ground 
about  every  alternate  four  hours  with  sufficient  force  to  turn  the  wheels 
of  several  mills,  has  now,  since  the  commencement  of  the  eighteenth  cen- 
tury, become  a  much  less  considerable  stream,  but  runs  constantly.* 
*  Yon  Kloeden,  Handbuch  der  Erdkunde, 


ASCENDING  SPRINOii.  231 


CHAPTER  XXXIX. 

ASCENDING   SPRINGS.  —  ABTESIAN    WELLS.  —  TEMPEEATUEB    OF    JETTING 

SPRINGS. 

There  are  many  of  these  subterranean  streams  which,  before  they  break 
forth  in  springs,  do  not  flow  over  beds  continuously  sloping  in^the  direc- 
tion of  their  current,  as  is  the  case  with  water-courses  on  the  surface  of 
the  ground.  There  are  some  indeed  which  first  descend  into  the  bowels 
of  the  earth,  either  by  a  uniform  declivity  or  by  a  series  of  cascades  or 
rapids,  and  ultimately  reascend  from  the  depths  toward  the  surface,  or  jet 
out  vertically  from  the  ground.  Let  us  follow  in  our  imagination  a  rill 
of  melted  snow  trickling  down  from  the  mountain  side  through  the  crev- 
ices of  the  earth  to  a  depth  of  some  hundreds  or  thousands  of  yards  be- 
low the  surface  of  the  ground.  So  long  as  this  water  does  not  meet  with 
any  impervious  stratum,  it  continues  to  sink  toward  the  lower  abysses. 
But  if  its  progress  is  arrested  by  a  bed  of  retentive  clay  or  any  other  layer 
through  which  it  can  not  pass,  it  will  spread  out  over  this  layer,  and  will 
follow  all  its  inflections.  Should  this  stratum  curve  gradually  upward  to- 
ward the  surface  of  the  ground,  or  should  it  even  rise  suddenly,  the  sub- 
terranean stream  will  reascend,  as  if  in  a  tube,  so  as  to  place  itself  in  a  po- 
sition of  equilibrium  with  the  other  liquid  masses  which  continue  to  de- 
scend from  the  heights. 

Added  to  this,  in  obedience  to  the  law  which  compels  liquids  to  seek 
the  same  level  in  all  connected  reservoirs,  a  rivulet  of  water  will  never 
fail  to  dart  forth  as  a  spring  as  soon  as  it  finds  an  outlet  below  the  cav- 
erns in  which  the  water  is  collected  from  which  it  proceeds.  Likewise,  if 
the  spot  where  the  gushing  out  takes  place  is  on  a  much  lower  level  than 
that  of  the  feeding  reservoirs  situated  above,  the  liquid  jet  must  necessa- 
rily shoot  up  in  a  column  above-the  surface  of  the  ground.  This  is  the 
case  at  Chatagna,  in  the  department  of  the  Jura,  where  a  natural  Je«  (Teau 
springs  up  to  a  height  of  10  or  12  feet.  In  the  grotto  of  Male-Mort,  near 
Saint-Etienne,  in  Dauphino,  the  jet  of  water  is  not  less  than  23  to  26  feet 
in  height.*  But  the  water  of  the  fountains  being  always  more  or  less 
charged  with  sediment,  the  deposit  accumulates  in  the  form  of  a  circular 
hillock  around  the  orifice,  thus  almost  always  ultimately  raising  it  to  the 
level  of  the  top  of  the  liquid  column.  As  an  instance  of  these  rising  foun- 
tains, we  may  mention  the  famous  springs  of  Moses  {A'in  Musa),  which 
gush  out  in  a  charming  oasis  not  far  from  the  shores  of  the  Gulf  of  Suez. 
These  springs,  the  temperature  of  which  varies  from  70°  to  84°  (Falir.),* 
_  now  flow  from  the  top  of  several  small  cones  of  sandy  and  slimy  debris 
which  they  have  gradually  thrown  up  above  the  level  of  the  plain.  They 
are  also  shaded  by  olive  and  tamarind  trees.  At  a  certain  distance  from 
*  Foumet,  Uydrologie  Souterraine. 


232 


THE  EARTH. 


the  spot  where  these  small  streams  gush  out,  there  is  a  line  of  dried-up 
cones.  These  are  the  former  fountain-heads,  which  are  now  abandoned  by 
the  water  on  account  of  their  too  great  elevation.* 

This  phenomena  of  the  springing  up  of  deep-lying  water  from  the  bow- 
els of  the  earth  is  a  fact  established  beyond  all  doubt  by  direct  obsei-va- 
tions ;  for,  many  centuries  ago,  the  absolute  necessity  of  finding  springs  of 
water  in  arid  countries  disclosed  to  the  nations  inhabiting  them  the  exist- 
ence of  these  sources  ascending  from  the  depths  of  the  earth.  In  the  des- 
erts of  Egypt  and  Algeria,  the  natives,  from  the  most  remote  antiquity, 
had  learned  how  to  bore  wells  30,  40,  and  even  90  feet  into  these  liquid 
veins,  and  thus,  in  the  very  midst  of  the  sands,  they  caused  the  rising  col- 
umns of  water  to  spout  out,  casting  life  and  riches  all  around  them.  The 
inhabitants  of  certain  valleys  in  Afighanistan  and  Arabia,  fearing  to  lose  a 
drop  of  the  precious  water  which  comes  down  to  them  from  the  moun- 
tains, have  had  the  foresight  to  take  possession  of  the  brooks  at  their  issue 
from  the  gorges,  and  to  inclose  them  in  subterraneous  tunnels,  inclined  ac- 
cording to  the  general  slope  of  the  soil.  The  water,  thus  protected  from 
the  heat  of  the  sun,  does  not  evaporate  at  all  en  route;  it  reaches  the  foot 
of  the  declivity  almost  without  waste,  and,  ascending  by  a  vertical  well 
into  the  outlet-reservoir,  flows  immediately  into  the  irrigation  trenches. 
The  greater  part  of  these  channels  are  piei-ced  here  and  there  with  aper- 
tures, through  which  the  cultivators  of  the  banks  of  the  river  draw  the 
water  necessary  for  their  crops.  Some  of  these  subterranean  streams  are 
not  less  than  36  miles  in  length.  They  are  rudimentary  imitations  of  the 
very  work  which  nature  herself  accomplishes  in  order  to  elaborate  her 
springs  and  cause  them  to  gush  out  from  the  surface  of  the  soil. 

Thanks  to  the  efticacious  means  of  boring  which  modern  ingenuity  has 
placed  in  the  hands  of  geologists,  men  do  not  content  themselves  with 
piercing  the  beds  of  clay,  sand,  and  stone  to  any  trifling  depth,  but  pene- 
trate hundreds  of  yards,  in  order  to  give  an  upward  egress  to  the  veins  of 
water  which  have  descended  from  the  mountains  or  distant  plateaux.  By 
means  of  the  second-sight  which  study  gives  him,  the  savant  can  point  out 
beforehand  with  almost  perfect  precision  the  course  of  the  subterranean 
waters,  and  even  the  quality  of  the  fluid.  Thus  the  engineers  bored 
through  the  soil  in  the  environs  of  Calais  in  the  hope  (which  was  justified 
by  the  result)  of  touching  upon  the  waters  which  had  come  from  the  hills 
of  England  under  the  Straits  of  Dover,  and  making  it  spring  up  in  their 
wells.  They  have  also  dug  with  perfect  confidence  in  the  precise  spot 
where  saline  or  medicinal  waters  flowed  under  the  ground.  In  the  Alge- 
rian Sahara,  the  engineers  mark  beforehand,  in  the  middle  of  the  barren 
and  arid  desert,  the  place  where  an  abundant  spring  ought  to  gush  out,  and 
^very  blow  of  the  boring-rod  brings  to  the  surface  a  jet  of  water,  which  is 
soon  surrounded  by  tents  and  the  budding  palm-trees  of  an  oasis. 

Thus,  although  the  sight  of  man  can  not  penetrate  through  the  beds  of 
rocks  piled  one  above  another,  yet  the  subterranean  course  of  the  streams 
is  none  the  less  visible  to  his  mind's  eye.     Besides,  these  subterranean 
*  Mittheilungen  von  Petermann,  1861. 


ARTESIAN  WELLS.— TEMPERATURE.  233 

waters  act  exactly  in  the  same  manner  as  those  which  flow  on  the  surface 
of  the  soil ;  they  also  carry  along  their  alluvium,  and  thus  contribute  their 
part  toward  modifying  the  relief  of  the  globe.  In  many  places,  especially 
at  Tours,  the  artesian  wells  have  ejected  the  remains  of  plants,  branches, 
moss,  snail-shells,  and  other  debris  which  the  rains  had  probably  carried 
away  some  weeks  previously  into  the  depths  of  the  earth.  AtElbceuf  the 
water  of  a  well  contained  living  eels.* 

Many  artesian  wells  reach  a  very  considerable  depth.  The  celebrated 
well  of  Grenelle  is  not  less  tlian  1771  feet  deep,  and  the  water  which  rises 
from  the  bottom  of  this  abyss  also  ascends  91  feet.  The  salt  water  which 
rises  from  the  artesian  spring  of  Neusalzwerk,  near  Minden,  proceeds  from 
a  depth  of  2394  feet.  A  spring  of  sulphurous  water  at  Louisville,  in  Ken- 
tucky, rises  in  a  bore  2086  feet  deep,  and  the  water  leaps  up  170  feet  from 
the  orifice.  A  well  dug  at  St.  Louis,  on  the  Missouri,  to  supply  a  sugar 
refinery,  exceeds  2624  feet  in  depth.  The  quantity  of  water  which  it  is 
possible  to  obtain  from  the  various  borings  is  very  considerable,  and,  in 
many  cases,  would  be  still  larger  if  the  ascending  tubes  had  a  wider  diam- 
eter. The  spring  of  Neusalzwerk  yields  321  gallons  a  minute;  an  arte- 
sian well  of  the  Oued  R'ir,  that  of  Sidi-Amran,  supplies  in  the  same  space 
of  time  884  gallons,  or  5  cubic  yards.  That  of  Passy,  at  Paris,  yields  7. 
cubic  yards.  In  some  spots,  a  large  number  of  artesian  wells  unite  into 
one  single  rising  column,  the  waters  of  two  or  more  sheets  of  fluid  rising 
one  above  another.  Thus,  at  Dieppe,  in  boring  a  well  1092  feet  in  depth, 
they  came  successively  upon  seven  very  abundant  water-bearing  strata. 


C20  miles. 
Fig.  76.  Artesian  System  of  Cued  R'ir;  after  Dubocq. 

In  all  artesian  springs  the  temperature  rises  the  farther  the  well  de- 
scends below  the  level  of  the  sea.  The  jet  from  the  well  of  Grenelle 
marks  82°  (Fahr.),  64°  (Fahr.)  more  than  that  of  Passy ;  that  is  to  say, 
that  at  this  point  of  the  terrestrial  crust  the  increase  of  heat  is  1°  (Fahr.) 
for  each  interval  of  55  feet  in  depth.  The  thermomctrical  study  of  other 
artesian  springs  has  given  results  differing  little  from  this,  and  it  can  bo 
strictly  stated  that  for  every  space  of  from  40  to  55  feet  of  vertical  height 
the  temperature  increases  on  an  average  1°  (Fahr.)  from  the  surface  of  the 
soil  to  the  lowest  beds  which  the  excavations  of  man  have  yet  penetrated.f 
In  the  springs  of  Sahara  the  increase  of  temperature  is,  according  to  M. 
Ville,  I''  (Fahr.)  to  36  feet  of  depth. 

*  Buff,  Phi/sik  tier  Erde.  \  Vide  above,  p.  30.  .3 1 . 


234  THE  EARTH. 


CHAPTER  XL. 

COLD   AND  THERMAL   SPRINGS. 

As  artesian  wells  only  differ  from  natural  springs  in  the  change  of  direc- 
tion given  to  their  waters,  the  same  laws  must  apply  to  all  subterranean 
currents,  consequently  the  depth  to  which  the  water  descends  into  the 
bowels  of  the  earth  maybe  approximately  ascertained  by  the  temperature 
of  a  spring.  It  may  be  confidently  affirmed  that,  in  a  general  way,  cold 
springs — that  is  to  say,  those  the  mean  temperature  of  which  is  lower 
than  the  heat  of  the  soil  —  descend  from  mountains,  and  that  thermal 
springs  proceed,  on  the  contrary,  from  beds  lying  deep  in  the  interior  of 
the  earth. 

In  the  innumerable  multitude  of  springs,  either  cold  or  thermal,  which 
rise  from  the  earth,  we  may  observe  the  whole  range  ,of  possible  tempera- 
tures from  freezing-point  up  to  the  boiling-point.  A  spring  which  flows 
from  the  side  of  the  Hangerer,  in  the  Oetzthal,  at  a  height  of  6742  feet,  is 
only  1°  warmer  than  ice.*  On  the  Alps,  the  Pyrenees,  and  all  the  other 
chains  of  snow-clad  mountains,  near  the  summits  small  rills  of  water  are 
very  frequently  met  with,  the  temperature  of  which  is  scarcely  higher 
than  that  of  melting  snow.  Even  at  the  bases  of  mountains,  and  especially 
those  of  a  calcareous  nature,  a  great  number  of  springs  are  found  which 
are  much  colder  than  the  surrounding  soil.  Geologists  who  have  applied 
themselves  to  the  study  of  subterranean  hydrography  have  had  many  op- 
portunities of  proving  the  truth  of  the  fact  that  drainage- waters  at  first 
maintain  a  temperature  considerably  lower  than  that  of  the  rocks.  This 
is  so  because,  in  addition  to  the  water,  the  air  also  enters  the.  subterranean 
channels  and  circulates  in  all  the  net-work  of  clefts  and  crevices,  and,  by 
incessantly  gliding  over  the  wet  sides  of  the  channels,  produces  a  rapid 
evaporation  of  moistui-e,  and,  in  consequence,  refrigerates  the  surface  of  the 
rocks  and  even  the  stream  itself.  The  temperature,  therefore,  of  springs 
which  proceed  from  the  interior  of  cavernous  mountains  is  always  several 
degrees  lower  than  the  normal  temperature  of  the  soil. 

The  greater  number,  however,  of  subterranean  rivulets  which  flow  at  a 
small  depth  below  the  surface  of  the  rocks  or  earth,  and  gush  forth  in 
'springs  after  having  slowly  traversed  a  slightly  inclined  extent  of  ground, 
ultimately  acquire  a  temperature  scarcely  differing  at  all  from  that  of  the 
soil.  The  simplest  means  of  approximately  ascertaining  the  mean  tem- 
perature of  any  particular  spot  is  to  plunge  the  thermometer  into  the 
spring-water ;  for,  as  the  extremes  of  heat  and  cold  are  inoperative  at  a 
depth  of  only  a  few  yards  below  the  surface  of  the  soil,  the  greater  num- 
*  ^on^wr,CEtzthaler  Gehirgsyrvppe. 


THERMAL  SPRINGS.  235 

ber  of  liquid  veins  are  not  liable  to  the  changing  influences  of  the  outer 
air,  and,  in  consequence,  show  at  their  emerging  point  the  real  average  cli- 
mate of  the  locality.  In  winter  the  Sorgue  of  Vaucluse  seems  to  smoke, 
on  account  of  the  rapid  condensation  of  its  vapor,  which  is  cooled  by  the 
atmosphere.  During  the  severe  winter  of  1819  to  1820,  when  the  Rhone 
was  completely  frozen  over,  and  might  be  safely  crossed  from  Avignon  to 
Villeneuve,  ^L  F.  de  Lanoye  tells  us,  the  whole  extent  of  the  Sorgue  re- 
mained perfectly  free  from  ice. 

Springs  which  have  a  higher  temperature  than  the  soil  are  called  ther- 
mal springs.  These  are  the  springs  the  depth  of  which  may  be  roughly 
estimated  by  calculating  a  descent  of  55  feet  for  each  degree  (Fahr.)  be- 
yond the  normal  heat  of  the  surrounding  soil.  Thus  the  springs  ofPlom- 
bieres,  which  have  a  temperature  of  149°  (Fahr.),  would  take  their  rise 
5413  feet  below  the  surface;  those  of  Chaudes-Aigues,  the  heat  of  which 
is  found  to  be  not  less  than  178°  (Fahr.),  issue  from  beds  situated  6889  feet 
from  the  surface  of  the  soil ;  lastly,  the  gushing  rivulet  of  Trincheras,  in 
Venezuela,  which  marked  206°  (Fahr.)  at  the  time  of  Boussingault's  visit 
in  1823,  would  proceed  from  rocks  at  a  still  more  considerable  depth. 

It  has  been  the  subject  of  direct  observation  in  the  wells  of  the  Geysers, 
in  Iceland,*  that  the  deep  water  in  the  interior  of  the  earth  may  attain  a 
temperature  considerably  above  212°  (Fahr.) ;  but  on  reaching  the  surface, 
this  boiling  water,  nearly  all  of  which  jets  forth  in  the  vicinity  of  volca- 
noes, must  necessarily  be  transformed  into  steam.  It  must,  moreover,  be 
remarked,  that  the  high  temperature  of  several  springs  is  owing  to  acci- 
dental causes.  When  the  volcano  of  Jorullo  made  its  appearance  in  1759, 
two  small  rivulets — the  rios  of  Cuitimba  and  San  Pedro — were  covered 
with  intensely  heated  scoria},  and  reappeared  farther  down  their  course  as 
thermal  springs.  In  1 803  the  lava  was  still  warm,  as  the  temperature  of 
the  springs  measured  by  Humboldt  exceeded  149°  (Fahr.);f  but  travelers 
who  have  recently  visited  the  district  of  Jorullo  aver  that  the  water  flow- 
ing from  the  base  of  the  volcano  has  gradually  cooled  since  the  commence- 
ment of  the  century,  and  that  soon  it  will  have  reached  the  normal  tem- 
perature of  the  surrounding  soil.  In  the  same  way  the  water  of  Bertrich- 
bad,  in  Luxembourg,  has  gradually  discontinued  to  be  either  warm  or  min- 
eral in  its  character  ever  since  the  lava  of  a  small  eruption  has  ceased  to 
come  in  contact  with  the  burning  furnace  which  produced  it.J 

It  is  to  be  remarked  that  nearly  all  thermal  springs  which  do  not  owe 
their  high  temperature  to  the  vicinity  of  volcanoes  issue  forth  from  faults 
which  open  on  the  surface  of  masses  of  a  crystalline  nature,  and  principally 
at  the  side  of  modem  eruptive  rocks  which  have  been  thrust  up  through 
older  strata.  This  must  evidently  be  the  case,  for  in  piercing  the  terres- 
trial crust  the  upheaved  matter  has  broken  through  the  parallel  layers 
which  detained  the  sheets  of  water,  and  by  this  rupture  of  the  strata  has 
opened  channels  by  which  the  springs  can  ascend  toward  the  surface  of 

*  Vide  the  chapter  on  "  Volcanoes. "  f  Humboldt,  Cosmos,  Ist  Part. 

I  Poulett  Scrope,  Volcanoes. 


236  T^^  EARTH. 

the  soil.  One  fact,  also,  that  proves  the  existence  of  these  deep  fissures 
whence  thermal  waters  spring  is  that  their  temperature  sometimes  changes 
suddenly  in  consequence  of  earthquakes  which  obstruct  the  former  faults, 
or  else  open  them  out  to  far  greater  depths.  At  the  time  of  the  earth- 
quake at  Lisbon,  the  temperature  of  a  spring  of  Bagneres  de  Luchon  sud- 
denly rose, ««  is  said,  from  46°  to  122°  Fahr.  (?),  and  since  that  date,  now 
more  than  a  century  ago,  the  action  of  the  spring  is  not  modified.  It  is 
also  said  that  the  thermal  springs  of  Bagneres  de  Bigorre  suddenly  be- 
came cool  at  the  time  of  the  great  earthquake  in  1660.* 

The  influence  of  rains  and  seasons  has  much  less  efi*ect  upon  thermal 
waters  than  upon  cold  springs  which  proceed  from  the  upper  layers  of  the 
soil.  A  great  number  of  warm  springs,  however,  undergo  certain  changes 
in  their  yield  of  water,  which  must  be  without  doubt  attributable,  at  least 
partially,  to  the  same  causes  as  the  variations  in  the  discharges  of  super- 
ficial streams.  In  Auvergne,  in  the  Pyrenees,  and  in  Switzerland,  several 
springs,  perfectly  protected  against  any  infiltration  of  rain-water,  flow  in 
much  greater  abundance  at  the  very  same  period  when  the  adjacent  tor- 
rents become  swollen.  It  is  true  that  the  increase  of  thermal  water  must 
be  partly  caused  by  the  lateral  pressure  exercised  by  the  cold  waters  sat- 
urating the  soil  and  forcing  back  all  the  small  scattered  rills  toward  the 
central  spring.  But  the  liquid  mass  proceeding  from  deep  beds  is  also 
much  stronger  (for  the  temperature  of  deep  springs  increases  simultane- 
ously with  the  yield),  doubtless  because  the  subterranean  rivulets,  when 
increased  in  volume,  are  less  retarded  in  their  course,  and  lose  less  heat  in 
mounting  toward  the  surface  of  the  ground.  At  Brig-Baden,  in  the  Val- 
ais,  the  water,  the  mean  temperature  of  which  is  in  autumn  and  winter 
from  71°  to  72°  (Fahr.),  rises  to  113°  and  122°  (Fahr.)  when  the  breath  of 
spring  melts  the  ice  on  the  Jungfrau.f  Many  of  the  phenomena,  however, 
exhibited  by  thermal  springs  are  still  rather  difficult  to  explain.  The 
greater  number,  therefore,  oi  savants  who  devote  themselves  fo  the  study 
of  subterranean  hydrology  admit  that  the  tension  of  gases  which  are  pro- 
duced in  the  interior  of  the  earth  plays  a  principal  part  in  the  emission  of 
thermal  waters. 

Most  thermal  springs  contain  mineral  substances  in  solution  ;  there  are, 
however,  a  certain  number  which  are  almost  as  pure  as  rain-water — such 
as,  for  instance,  the  celebrated  waters  of  Plombi^res,  which  do  not  even 
contain  ^^jny  of  salts;  also  that  of  Gastein,  Pfeffers,Wildbad,  and  Baden- 
weiler.J  The  springs  of  Chaudes-Aigueg — those  in  France  which  have 
the  highest  temperature,  1 58°  to  1 76°  (Fahr.) — contain  only  a  small  amount 
of  mineral  substances.  The  inhabitants  of  Chaudes-Aigues  use  the  water 
to  prepare  their  food,  to  wash  their  linen,  and  to  warm  their  houses. 
Wooden  conduits,  erected  in  all  the  streets  of  the  town,  supply,  on  the 
ground  floor  of  each  house,  a  reservoir  which  serves  to  heat  it  during  cold 
weather,  and  thus  dispenses  with  fires  and  chimneys.     In  summer,  small 

*  Lyell,  British  Association  at  Bath,  1864.  t  Filhol,  Eaux  des  Pi/r€n(fes. 

X  Buff,  Physik  der  Erde. 


THERMAL  SPRINGS.— HEAT  UTILIZED.  237 

sluices,  placed  at  the  entrance  of  each  conducting  tube,  stop  the  warm 
water  alid  throw  it  back  into  the  rivulet  which  flows  at  the  bottom  of  the 
town.  M.  Bertbier,  a  chemist,  has  calculated  that  the  heat  furnished  daily 
by  the  springs  is  equal  to  that  which  the  combustion  of  more  than  four 
tons  and  a  half  of  coal  would  produce.  It  is  suflScient  to  give  a  comfort- 
able temperature  to  the  interior  of  the  houses  and  to  warm  the  streets 
themselves.  The  snow,  which  falls  in  great  abundance  during  winter, 
melts  immediately  after  its  fall.*  There  are  not  perhaps  in  the  world  any 
thermal  springs  the  heat  of  which  is  better  utilized. 

*  Allard  and  Boucomont,  Euux  Thernut-minirales  d  'Auvergne. 


238  ^-^^  EARTH. 


CHAPTER  XLL 

MTNTEBAL   SPRINGS. — INCRUSTING   SPRINGS. — METALLIC   VEINS. — SALT 

SPRINGS. 

Spring-water,  cold  as  well  as  hot,  is  rarely,  if  indeed  ever,  pure  from 
all  admixture ;  thousands  of  samples  analyzed  even  in  our  time  by  chem- 
ists do  not  furnish  a  single  instance  of  spring-water  which  does  not  con- 
tain a  greater  or  less  proportion  of  calcareous  or  magnesian  salts.  The 
purest  water  that  the  French  chemists  have  yet  found  is  that  of  the  Dome, 
a  small  river  of  Ardeche,  and  this  may  almost  be  compared  to  distilled 
water.  In  the  other  mountainous  regions  of  Central  France,  water,  con- 
sidered quite  excellent  in  its  character,  is  charged  with  two,  three,  four,  or 
even  ten  times  more  calcareous  matter.  The  water  of  the  Seine  contains, 
on  an  average,  thirty-six  times  more  extraneous  matter,  and  some  wells 
at  Paris  and  Marseilles,  the  water  of  which  is,  notwithstanding,  used  for 
drinking,  are  250  to  350  times  less  pure.* 

Among  the  various  substances  which  spring-water  brings  to  the  sui-face, 
those  which  are  most  common  proceed  from  the  strata  which  serve  to  con- 
stitute the  very  frame-work  of  the  globe.  Chalk,  especially,  occurs  in  dif- 
ferent proportions  in  most  springs,  either  under  the  form  of  sulphate  of 
lime,  or,  more  often,  as  carbonate  of  lime.  Water  which  contains  carbonic 
acid  in  solution  is  charged  with  calcareous  matter  dissolved  away  from  the 
sides  of  the  rocks  through  which  it  passes ;  then,by  means  of  evaporation, 
it  redeposits  the  stony  substances  which  it  previously  held  in  solution. 
Hence  arise  all  those  calcareous  concretions  which  form  around  so  many 
springs ;  also  the  stalactites  in  caverns,  and  even  those  dangerous  incrus- 
tations which  accumulate  in  the  boilers  of  locomotives. 

Nearly  all  countries  of  the  world  possess  some  of  these  curious  springs, 
which  cover  with  a  calcareous  crust  any  object  placed  in  their  waters. 
Among  these  incrusting  springs,  those  of  Saint  Allyre,  near  Clermont,  Ri- 
voli,  and  San  Filippo,  not  far  from  Rome,  have  justly  become  celebrated. 
These  latter  have,  in  a  space  of  twenty  years,  filled  up  a  pond  with  a  bed. 
of  travertin  30  feet  thick,  and,  in  the  neighborhood,  entire  strata  of  this 
same  rock  may  be  seen  having  a  depth  of  more  than  328  feet.f  The 
springs  of  Hammam-Mes-Khoutine,  in  the  province  of  Constantine,  are  also 
very  remarkable  on  account  of  the  considerable  amount  of  their  deposits. 
This  water,  which  rises  at  a  temperature  of  203°  (Fahr.),  and  from  which 
a  high  column  of  steam  always  rises,  is  frequently  compelled  tt)  change  its 
point  of  issue  on  account  of  the  dense  beds  of  travertin  which  are  gradu- 

*  Robinet,  Discus-iion  sur  les  Enux  Potables. 
t  Lyell,  Princijiles  of  Geology. 


INCRUSTINO  SPRINGS.  239 

ally  deposited  upon  the  soil.  Most  of  these  deposits  are  of  a  dazzling 
white  hue,  striped  here  and  there  with  bright  colors,  and  are  developed  in 
maminillated  strata ;  other  concretions,  accumulating  gradually  round  an 
oriffce,  have  taken  the  form  of  cones,  and  are  like  the  small  craters  near 
a  volcano,  some  of  them  rising,  to  a  height  of  as  much  as  33  feet;  lastly, 
there  are  masses  of  travertin  which  stretch  out  in  a  kind  of  wall  below  the 
flow  which  deposits  them.  One  pf  these  walls,  which  is  interrupted  at  in- 
tervals by  heaps  of  earth  upon  which  large  trees  grow,  is  not  less  than  4921 
feet  long,  66  feet  high,  and,  on  an  average,  from  33  to  49  feet  wide.* 
.  The  thermal  waters  of  Algeria  are,  however,  surpassed  in  grandeur  and 
beauty  by  the  spriflgs  of  the  ancient  Ionian  city  of  Ilierapolis  (holy  city), 
which  at  the  present  time  flow  in  the  solitary  plateau  called  Panbouk- 
Kelessi  (Castle  of  Cotton),  on  account  of  the  cotton-like  aspect  of  the 
white  masses  of  travertin  of  which  it' is  composed.  On  reaching  this  spot 
from  Smyrna,  something  like  an  immense  cataract  may  be  seen  in  the  dis- 
tance, 328  feet  high  and  2^  miles  wide ;  this  is  formed  by  the  walls  which 
the  water  has  gradually  constructed,  column  after  column,  and  layer  after 
layei',  by  flowing  over  the  edges  of  the  plateau  and  gushing  out  on  the 
slopes.  Here  and  there,  real  cascades  glitter  in  the  sun,  and  their  spark- 
ling surfaces  light  up  the  dead  whiteness  of  the  crystal  walls.  As  a  spec- 
tator ascends  the  declivities,  the  masses  deposited  and  carved  out  by  the 
water  appear  in  all  their  strange  beauty ;  one  might  fancy  that  they  were 
colonnades,  groups  of  figures,  and  rude  bas-reliefs  which  the  chisel  had 
not  yet  perfectly  set  free  from  their  rough  coverings  of  stone.  And  all 
these  calcareous  deposits  which  have  been  fashioned  by  the  cascades  dur- 
ing a  succession  of  ages  open  a  multitude  of  cup-like  hollows  with  fluted 
edges  fringed  with  stalactites ;  these  graceful  reservoirs — some  of  which 
are  shaded  with  yellow  or  veined  wnth  red,  brown,  and  violet,  like  jasper 
or  agate — are  filled  with  pure  water.  Higher  still  follow  two  steps  of  the 
plateau  on  which  stood  the  ancient  thermal  edifice  and  the  Necropolis  of 
Hierapolis.  There,  whitish  masses  cover  the  ancient  tomb-stones  and  fill 
up  the  conduits.  The  ground  is  crossed  in  various  directions  by  the  for- 
mer beds  of  rivulets,  which  have  gradually  stopped  up  their  own  courses 
by  depositing  conci-etions  upon  them.  Above  one  of  the  widest  of  these 
dried-up  channels,  the  magnificent  span  of  a  natural  bridge  displays  its 
graceful  form,  like  an  arch  of  alabaster,  streaming  with  innumerable  sta- 
lactites.f  At  what  date  did  this  majestic  structure  take  its  rise,  and  how 
many  years  and  centuries  did  the  process  of  its  formation  last?  No  one 
knows.  According  to  Strabo,  the  channels  of  the  baths  of  Hierapolis  were 
soon  filled  up  by  solid  masses,  and  if  Vitruvius  can  be  believed,  when  the 
proprietors  of  the  environs  wished  to  inclose  their  domain,  they  caused 
a  current  of  water  to  run  along  the  boundary-line*  and  in  the  space  of  a 
year  the  walls  had  risen. 

Silica,  which  is  still  more  important  than  chalk  in  the  formation  of  ter- 

*  Grellois,  Lrs  Di'p6ts  Cnlcaires  de  Hammnm-Mfs-Khoutine. 
t  Tchihatchcf,  Le  Boaphore  et  Constantinople. 


240 


THE  EARTH. 


77.  Natural  Biidi:e  of  Paubouk-Kelessi- after  Tchihalchef. 


restrial  rocks,  is  also  sometimes  deposited  on  the  edge  of  springs,  but  in 
very  small  quantities;  only  those  waters  which  are  of  a  very  high  tem- 
perature can  dissolve  silica  in  sufficient  quantities  to  form  a  deposit  round 
their  outlet,  and  produce  beds  of  any  considerable  thickness.  Among  the 
spiings  which  are  charged  with  silica,  the  best  known  are  the  Geysers  of 
Iceland,  the  boiling  waters  of  which  deposit  round  their  orifice  circular  lay- 
ers of  siliceous  concretions  several  yards  high.*  Other  volcanic  springs 
are  no  less  active,  and  even  at  a  long  distance  from  any  volcano  there  are 
few  thermal  springs  which  do  not  contain  silica  in  quantities  more  or  less 
perceptible. 

Concretions  and  crystallizations  formed  by  thermal  waters  in  the  very 
interior  of  fissures  or  lines  of  fault  have  geologically  more  importance  than 
external  deposits,  and  can  be  produced  at  a  much  lower  temperature  than 
in  the  open  air.  M.  Daubree  has  seen  these  phenomena  in  action  at  the 
springs  of  Plombieres.  The  ancient  Roman  masonry  which  was  used  for 
storing  and  supplying  water  is  filled  with  zeolites  or  siliceous  crystals,  ev- 
idently owing  to  the  prolonged  influence  of  the  water  and  its  slow  chem- 
ical reaction  on  the  calcareous  cement  and  the  bricks.  The  intimate  struc- 
ture of  these  materials  has  been  modified  by  this  water,  the  heat  of  which 
does  not,  however,  exceed  140°  to  158°  (Fahr.).  It  is  doubtless  a  similar 
chemical  action,  due  to  these  thermal  waters,  which  has  produced  in  all 
*  Vide  chapter  on  "Volcanoes." 


MINERAL  VEINS.  241 

the  fissures  of  Plombi^res  the  vein  of  quartz,  opal,  and  fluor  spai*  which 
are  found  there.  The  enormous  deposits  of  a  quartz-like  nature  in  an  ad- 
jacent valley,  that  of  Roches,  are  results  of  the  same  geological  work.* 

It  is  probable  that  at  33,000  or  39,000  feet  deep  in  these  abysses,  where 
the  water,  still  retaining  a  liquid  state,  may  attain  to  a  temperature  of 
500°  to  600°  (Fahr.),  the  chemical  operations  of  subterranean  waters  are  ac- 
complished with  much  more  activity  than  in  beds  near  the  surface.  Most 
geologists  think  that  thermal  vapors  can  dissolve  not  only  those  metals 
which  melt  at  low  temperatures,  such  as  tin  and  lead,  but  also  copper, 
gold,  and  silver.  Veins  containing  metals  are  probably  only  fissures  in 
which  these  thermal  vapors  have  become  cooled,  and  have  then  deposited 
the  metallic  substances  with  which  they  were  charged.  Gold,  silver,  and 
copper  remain  in  the  depths  of  the  earth,  and  the  waters  bring  up  to  the 
basin  of  the  spring  nothing  but  a  small  quantity  of  salts,  silicates,  and 
gases.  Then  follow  the  gradual  movements  of  the  crust  and  the  geolog- 
ical revolutions  which  cause  the  metallic  veins  to  rise  to  the  level  of  the 
ground,  or,  at  least,  which  bring  them  nearer  to  the  surface.f 

The  various  dislocations  of  the  terrestrial  strata,  the  cooling  of  the  wa- 
ters, and,  perhaps,  in  many  instances,  the  obstruction  of  channels  by  de- 
posits of  ore,  explain  why,  in  the  present  period,  so  small  a  number  of 
thermal  springs  issue  from  metalliferous  beds.  Nevertheless,  many  lo- 
calities might  be  mentioned  where  this  phenomena  takes  place  at  the 
present  time.  A  spring  at  Badenweiler,  in  the  Black  Forest,  issues  forth 
at  a  few  yards  from  a  vein  of  sulphuret  of  lead.  In  the  granitic  plateau 
of  Central  France  other  springs  are  likewise  found  to  be  associated  with 
this  metal.  Various  thermal  waters  in  the  Black  Forest,  like  those  of 
Carlsbad  and  Marienbad,  are  in  close  connection  with  veins  of  iron  and 
manganese.  Oligiste  iron  is  found  in  the  fissures  of  the  springs  of  Plora- 
bieres  and  Chaude-Fontaine.  In  Tuscany  sulphureous  fumaroles  proceed 
from  the  veins  of  antimony.  In  France  and  Algeria  the  waters  of  Syl- 
vanes  and  Hammam  R'ira  issue  forth  from  beds  of  copper.  Lastly,  near 
Freyberg,  a  voluminous  thermal  spring  has  been  discovered  in  a  vein  of 
silver.^ 

Among  the  mineral  substances  which  some  springs  bring  to  the  surface 
of  the  soil,  the  most  important,  in  an  economical  point  of  view,  is  common 
salt.  This  substance,  being  one  of  those  which  dissolves  most  readily  in 
water,  all  the  liquid  veins  which  pass  over  saline  beds  become  saturated 
with  salt ;  therefore  springs  of  this  kind,  which  flow  in  great  abundance, 
give  rise  to  salt-works  of  more  or  less  importance.  The  masses  of  com- 
mon salt  which  make  their  way  every  year  from  the  interior  of  the  earth 
may  be  estimated  at  thousands  of  tons.  The  springs  of  Halle,  which  rise 
on  the  northern  slope  of  the  Alps  of  Salzburg  (Salt  Town),  and  are  man- 
aged with  the  greatest  care,  annually  produce  15,000  tons  of  this  mineral. 

*  Daubr<?e,  Bulletin  de  la  Sociiti  de  Giologie,  IS.'iO. 

+  Lyell,  British  Association  at  Bath,  1864. 

X  Daubr^e,  Bulletin  de  la  Societi  de  Giologie,  1859. 

Q 


242  ^-^^  EARTH. 

The  salt  springs  of  Halle,  in  Prussia,  which  have  been  worked  from  time 
immemorial  by  a  company,  furnish  10,000  tons  of  salt  every  year.  Other 
parts  of  Germany  also  yield  for  consumption  thousands  of  tons  of  white 
salt,  which. is  produced  by  the  evaporation  of  saline  springs.  The  mass 
of  salt  furnished  by  the  single  artesian  well  of  Neusalzwerk,  near  IVIinden, 
in  Prussia,  represents  every  year  a  cube  measuring  78  feet  on  each  side.* 

Though  not  so  rich  as  Germany  in  saline  springs  thus  turned  to  account, 
most  of  the  civilized  countries  of  the  world  posse'ss  salt-works  which  are 
also  very  important.  France  enjoys  the  springs  of  Dieuze,  Salins,  and 
Salies ;  Switzerland,  those  of  Bex ;  Italy  has  the  springs  in  the  environs 
of  Modena,  and  many  others  besides.  In  England,  near  Chester,  there  are 
some  mines  of  rock-salt  in  which  numerous  liquid  veins  issue  forth  which 
are  impregnated  with  salt.  Lastly,  the  United  States  have  the  celebrated 
springs  of  Saratoga.  But  how"  many  saline  springs,  still  more  abundant, 
flow  uselessly  along  in  the  solitudes  of  the  world ! 

Not  far  from  the  "  spot  where  Troy  once  stood"  is  the  valley  of  Touzla- 
sou,  which  owes  its  name  (Salt  Water)  to  its  numerous  salt  springs.  The 
mountains  which  rise  around  its  circumference  are  variously  shaded  with 
blue,  red,  and  yellow,  and  the  rocks  are  incessantly  decomposing  under 
the  action  of  the  liquid  salt  which  oozes  out  from,  and  trickles  down  their 
sides.  The  plain  itself  is  covered  with  a  variegated  crust,  while  jets  of 
boiling  water,  saturated  with  salt,  burst  forth  in  every  direction.  Here 
and  there  pools  are  found,  the  moisture  of  which,  by  evaporating  in  the 
sun,  leaves  upon  the  soil  beds  of  salt  as  white  as  snow.  Near  the  mouth 
of  the  valley  springs  become  more  and  more  numerous.  Lastly,  in  the 
place  where  the  clifls  approach  near  together,  so  as  to  form  a  defile,  a 
magnificent  spout  of  water  jets  out  from  one  side  of  the  rock.  This  jet  is 
not  less  than  a  foot  in  diameter  at  the  orifice,  and  falls  again  after  having 
described  a  parabola  of  more  than  a  yard  and  a  half  Other  springs  shoot 
out  on  both  sides,  the  constant  temperature  of  which  is  more  than  212° 
(Fahr.) ;  these,  together  with  the  principal  jet,  form  a  rivulet  of  boiling 
and  steaming  water.  It  would  be  easy  to  extract  from  these  springs  an 
enormous  annual  supply  of  salt ;  but  the  negligence  of  the  Turkish  gov- 
ernment, who  have  appropriated  the  valley  of  Touzla-sou,  has  prevented 
more  than  one  thousand  tons  a  year  being  obtained,  f 

Springs  of  salt  water  are  used  for  the  treatment  of  diseases  as  well  as 
for  the  extraction  of  salt.  They  constitute  one  of  the  most  important 
groups  of  medicinal  waters,  according  to  the  various  susbstances  which 
they  contain  in  solution.  The  other  springs  made  use  of,  on  account  of 
their  healing  virtues,  have  been  classed  under  ferruginous,  sulphureous, 
and  acidulous  springs.  These  waters  also  contain,  in  different  proportions, 
a  variable  quantity  of  gases  and  salts  which  they  have  dissolved  in  their 
passage  over  subterranean  beds  of  every  kind.  It  is  probable  that  the 
proportion  of  gases  dissolved  in  the  water  fluctuates  with  all  the  varia- 
tions of  temperature  and  pressure  of  the  surrounding  air.  It  even  ap- 
*  BuflF,  Physik  der  Erde.  t  Tchihatchef,  Le  Dosj)hore  et  Constantinople. 


HOT  AND  SALINE  SPRINGS. 


243 


pears  that  a  simple  movement  of  the  liquid  is  snfScient  to  alter  the  con- 
stituents of  the  ^ter  as  regards  its  gaseous  elements ;  but,  on  the  whole, 
the  chemical  composition  is  tolerably  permanent,  and  there  is  no  doubt  as 
to  the  particular  virtue  of  every  spring  which  renders  it  fit  for  the  treatment 
of  one  or  many  special  diseases.  Thanks  to  this  healing  power,  of  all  the 
resources  of  which  science,  still  imperfect,  is  yet  ignorant,  medicinal  wa- 


Flg.  78.  Saline  Springs  of  Touzla. 


ters  serve  as  a  guide  to  a  more  familiar  acquaintance  with  nature,  for 
every  year  thousands  and  hundreds  of  thousands  of  visitors  are  attract- 
ed by  them  to  the  most  picturesque  and  majestic  spots  on  the  face  of  the 
earth. 

In  fact,  mineral  springs,  which,  for  the  most  part,  are  also  thermal,  hav- 
ing flowed  from  deep  beds,  nearly  all  issue  forth  at  the  point  of  contact 
between  older  rocks  and  more  modern  formations.  Now  these  points  of 
contact  are  especially  found  in  mountainous  countries,  which  also  receive 
from  the  atmosphere  larger  quantities  of  water  than  plains  do.  Mineral 
springs  are  most  numerous  and  abundant  in  mountain  valleys,  and  there, 
consequently,  the  great  thermal  institutions  are  established.  In  Europe 
the  chain  of  the  Pyrenees  is  probably  the  richest  in  mineral,  sulphureous, 
saline,  ferruginous,  and  acidulous  springs.  According  to  Francis,  the  en- 
gineer, in  18G0  more  than  550  mineral  springs,  187  of  which  are  used,  flow- 
ed upon  the  French  slopes  of  the  Pyrenees.     These  waters  supplied  83 


244  ^^^  EARTH. 

hot  baths  in  53  localities,  the  principal  of  which  are  Bagneres  de  Bigorre, 
Luchon,  Eaux-Bonnes,  and  Cauterets.  The  most  abundant  springs,  those 
of  Graus  d'Olette,  form  a  sort  of  mineral  stream,  yielding  more  than  four 
gallons  a  second,  or  2322  cubic  yards  a  day.  In  Algeria  the  spring  of 
Hammam-Mes-Khoutine  yields  6  gallons  a  second. 

There  are  regions,  some  volcanic  and  some  not,  in  which  nearly  all  the 
springs  are  thermal  and  mineral ;  springs  of  pure  and  fresh  water  being  so 
rare,  they  are  there  considered  to  be  most  precious  treasures.  One  of 
these  regions  comprehends  a  large  part  of  the  plateau  of  Utah.  In  this 
place  numerous  thermal  springs  issue  forth,  to  which  have  been  given  the 
vulgar  names  of  the  Beer,  Steam-boat,  Whistle  springs,  etc.,  and  into  one 
of  which  the  Mormons  plunge  their  neophytes.  The  springs  which  are 
not  thermal  are  loaded  with  saline  and  calcareous  matter.  It  is  only  in 
spring,  at  the  time  when  the  snow  melts,  that  the  springs,  which  then  be- 
come very  abundant,  yield  comparatively  pure  water.  During  the  dry 
season,  salt  and  carbonate  of  lime  become  concentrated  in  the  nearly  ex- 
hausted springs,  and  give  to  the  liquid  flow  an  unpalatable  taste.  Pal- 
grave,  the  traveler,  informs  us  that  all  the  springs  of  the  country  of  Hasa, 
in  Arabia,  are  also  thermal. 

It  can  readily  be  understood  that  when  all  these  substances  escape  from 
the  interior  of  the  rocks,  together  with  the  water  which  holds  them  in  so- 
lution, they  must  leave  empty  spaces  in  the  earth.  During  the  course  of 
long  centuries  whole  strata  are  dissolved,  and,  under  a  form  more  or  less 
chemically  modified,  are  brought  up  from  the  depths  and  distributed  on 
the  surface  of  the  soil.  The  thermal  waters  of  Bath,  which  are  far  from 
being  remarkable  for  the  proportion  of  mineral  substances  they  contain, 
bring  to  the  surface  of  the  earth  an  annual  amount  of  sulphates  of  lime 
and  soda,  and  chlorides  of  sodium  and  magnesium,  the  cubic  mass  of 
which  is  not  less  than  554  cubic  yards.*  It  has  also  been  calculated  that 
one  of  the  springs  of  Loufeche,  that  of  Saint  Laurent,  brings  every  year  to 
the  surface  8,822,400  pounds  of  gypsum,  or  about  2122  cubic  yards;  this 
quantity  is  enough  to  lower  a  bed  of  gypsum,  a  square  mile  in  extent, 
more  than  five  feet  in  one  century.  But  this  is  only  one  spring,  and  we 
have  reckoned  one  century  only ;  if  we  think  of  the  thousands  of  mineral 
springs  which  gush  from  the  soil,  and  of  the  immensity  of  time  during 
which  their  waters  have  flowed,  some  idea  may  be  formed  of  the  import- 
ance of  the  alterations  caused  by  spiings.  In  time  they  lower  the  whole 
mass  of  mountains,  and  no  doubt,  after  these  sinkings,  violent  oscillations 
of  the  earth  may  often  have  taken  place.f 

*  Ramsay.     "LyQW,  British  Association  at  Bath,  18G4. 
t  Otto  Volger,  Ueber  das  Phanomen  der  Erdbeben,  ^  ol.  ii. 


SUBTERRANEAN  WATER- COURSES. 


245 


CHAPTER  XLU. 

SUBTERRANEAN    RIVERS. — THE    SPRING    OF  VAUCLUSE,  THE   TOUVRE. — SUB- 
MARINE   AFFLUENTS. — THE    RIOS    OF   YUCATAN. THE  *' MUD-LUMPS"    OF 

THE    MISSISSIPPI. 

In  regions  where  the  strata  are  pierced  with  wide  and  deep  caverns, 
and  especially  in  calcareous  countries,  the  waters  sometimes  accumulate 
in  sufficient  quantities  to  form  perfect  streams  with  long  subterranean 
courses.  At  their  issue  from  the  caverns,  these  waters  form  a  contrast 
with  the  rocks  and  hills  around,  all  the  more  striking  because  the  latter 
are  completely  devoid  of  moisture,  and  fearfully  sterile,  while  on  the  brink 
of  the  limpid  stream  the  fresh  verdure  of  plants  and  trees  is  at  once  de- 


Fig.  79.  Vancluse  and  the  Sorgues. 

veloped.  Like  a  captive,  joyous  at  seeing  the  light  once  more,  the  water 
which  shoots  forth  from  the  sombre  grotto  of  rocks  sparkles  in  the  sun, 
and  careers  along  with  a  light  murmur  between  its  flowery  banks. 

Among  these  subterranean  streams,  the  most  celebrated,  and  doubtless 
one  of  the  most  beautiful,  is  the  Sorgues  of  Vaucluse.  The  vaulted  grotto 
from  which  the  mighty  mass  of  water  escapes  opens  -at  the  mouth  of  an 
amphitheatre  of  calcareous  rocks  with  perpendicular  sides.  Above  the 
spring  rises  a  high  white  cliff,  bearing  on  its  summit  a  ruined  tower  of  the 
Middle  Ages;  the  rock  is  every  where  sterile  and  bare;  there  is  nothing 
but  a  miserable  fig-tree,  clinging  to  the  stone  like  a  parasitical  plant  to  the 
bark  of  a  tree,  which  has  plunged  its  roots  into  the  fissure  of  the  cave, 
and  greedily  absorbs  with  its  leaves  the  moisture  which  floats  like  a  mist 
above  the  cascades  of  the  spring.  After  heavy  rains,  the  liquid  mass, 
which  is  then  estimated  at  26  or  even  32  cubic  yards  a  second,  flows  in  a 


246  ^^^  EARTH. 

wide  sheet  high  above  the  entrance  to  the  cavern,  which  is  then  altogeth- 
er inaccessible.    When  the  waters  are  low,  they  flow  bubbling  across  the 


Fig.  SO.  Course  of  the  Toiivre. 


barrier  of  rocky  debris  which  obstructs  the  entrance ;  at  that  time  it  is 
quite  possible  to  penetrate  under  the  arch,  and  to  contemplate  the  vast 
basin  in  which  the  blue  waters  of  the  subterranean  stream  spread  out  be- 
fore they  leap  into  the  open  air.  Soon  after  its  issue  from  the  cave  and 
amphitheatre  of  Vaucluse,  the  Sorgues  is  divided  into  numerous  irrigation- 
channels,  which  spread  fertility  in  the  country  over  an  area  of  more  than 
77  square  miles.  The  subterranean  course  of  the  afiluents  which  form  the 
stream  is  not  ascertained ;  but  it  is  known  that  most  of  them  commence 
12  or  15  miles  to  the  east,  in  the  plateaux  of  Saint  Christol  and  Lagarde, 
which  are  pierced  all  over  with  avens  or  chasms,  into  which  the  rain-water 
sinks  and  disappears. 

In  another  part  of  France  there  is  a  second  important  subterranean 
stream,  which  is  much  less  known  but  no  less  remarkable  than  that  of 
Vaucluse ;  this  is  the  Touvre  of  Angouleme,  continuing  the  course  of  the 
Bandiat,  the  waters  of  which,  like  those  of  the  Tardoire,  are  swallowed  up 
in  several  abysses  at  distances  varying  from  3  to  7  miles  to  the  east  and 
northeast.  The  three  principal  springs  of  the  Touvre  flow  slowly  out  of 
a  deep  cave,  hollowed  out  at  the  base  of  an  escarped  cliff";  another  spring 
bubbles  up  in  a  basin  of  rocks;  the  third  emerges  from  a  sort  of  boggy 


SUBMARIXE  OUTLETS  OF  RIVERS.  247 

meadow  intersected  by  drains.  At  the  outlet  of  their  subterranean  courses 
these  three  enormous  springs  immediafely  form  three  streams,  which  re- 
unite, leaving  between  them  two  long  peninsulas  of  reeds  and  other  aquat- 
ic plants.  Below  the  junction,  the  Touvre,  which  is  here  more  than  100 
yards  wide,  passes  round  a  rugged  hill,  and,  dividing  into  several  branch- 
es, turns  the  numerous  mill-wheels  of  the  impoi-tant  gun-foundery  of  Ru- 
elle;  then,  after  a  course  of  five  miles,  it  flows  into  the  Charente  at  a  small 
distance  above  Angouleme.  Among  the  hundreds  and  thousands  of  trav- 
elers whom  steam  annually  conveys  over  the  bridge  of  the  Touvre,  there 
are  few  who  are  aware  of  the  curious  nature  of  the  source  of  the  river  of 
limpid  water  over  which  the  train  passes  in  its  noisy  career. 

Omitting  to  mention  the  streams  which  accidentally  pass  under  the 
strata  of  rocks  during  a  small  part  of  their  course,  or  of  the  subterranean 
outlets  of  certain  lakes,*  a  multitude  of  other  instances  might  be  brought 
forward  of  masses  of  water,  more  or  less  abundant,  which  appear  above 
ground  after  having  traversed  a  considerable  distance  under  the  earth. 
Of  this  kind  is  the  graceful  spring  of  Nimes,  the  blue  transparent  water 
of  which,  reflecting  the  foliage  of  pines  and  chestnut  trees,  glides  in  its 
gentle  ripples  over  the  semicircular  steps  of  an  old  Roman  staircase.  Of 
this  kind,  too,  is  the  spring  of  Veneran,  near  Saintes :  this  spring,  which 
was  formerly  sacred  to  the  Goddess  of  Love,  gushes  from  the  ground  in  a 
gorge  of  rocks,  and,  passing  through  a  mill,  the  wheel  of  which  it  tunis,  it 
suddenly  disappears,  being  swallowed  up  in  an  abyss ;  thus  it  appears  on 
the  earth  to  work  but  for  an  instant. 

Numbers  of  water-courees  do  not  reappear  on  the  surface  of  the  soil 
after  being  swallowed  up  in  the  earth,  but  flow  straight  to  the  sea  by 
means  of  subterranean  channels.  On  nearly  the  whole  extent  of  the  con- 
tinental shores,  and  principally  in  localities  where  the  coasts  are  of  a  cal- 
careous nature,  the  outlets  of  submarine  tributaries  may  be  noticed,  some 
of  which  are  perfect  rivers.  Most  of  the  springs  of  the  department  of 
Bouches  du  Rhone  jet  up  from  the  bottom  of  the  sea,  but  at  various  dis- 
tances from  the  shore.  One  of  them,  that  of  Porte  Miou,  near  Cassis, 
forms  on  the  surface  of  the  sea  a  considerable  current,  which  drifts  any 
floating  bodies  to  a  great  distance.f  At  Saint  Nazaire,  Ciotat,  Cannes, 
San  Remo,  and  Spezzia,  other  streams  also  issue  from  the  midst  of  the  salt 
waves,  and  attempts  have  even  been  made  to  measure  approximately  their 
discharge.  M.Villeneuve-Flayosc  estimates  at  24  cubic  yards  a  second 
the  quantity  of  water  discharged  into  the  sea  by  all  the  hidden  affluents 
of  the  Mediterranean  between  Nice  and  Genoa.  Some  of  the  submarine 
springs  of  Provence  and  Liguria  proceed  from  enormous  depths.  The  ori- 
fice of  the  spring  of  Cannes  is  631  feet  below  the  level  of  the  sea;  that  of 
San  Remo  rises  from  a  depth  of  954  feet ;  lastly,  at  four  miles  to  the  south 
of  Cape  Saint  Martin,  between  Monaco  and  Mentone,  another  stream  of 
fresh  water  empties  itself  under  a  bed  of  salt  water,  near  2296  feet  deep.  J 

♦  Vide  the  chapter  on  "Lakes."  +  Marsigli,  Uistoire  Physique  de  la  Mer. 

X  VUleneuve-Flayosc,  Description  Giologique  du  Far. 


248  ^^-^  EARTH. 

The  coasts  of  Algeria,  Istria,  Dalmatia,  and  the  Herzogovina  also  pre- 
sent numerous  instances  of  subniarine  streams ;  on  the  eastern  shores  of 
the  Adriatic  the  traveler  may  even  have  the  pleasure  of  contemplating 
the  delta  of  a  considerable  river,  the  Trebintchitza,  visible  through  the 
sea-water  at  the  depth  of  a  yard.  The  abundant  springs  of  fresh  water 
which  pour  out  into  the  open  sea  to  the  southwest  of  the  Cuban  port  of 
Batabano  are  well  known,  since  Humboldt  described  them,  and  it  is  ob- 
served that  the  lamantins,  or  sea-cows,  which  dread  salt  water,  delight  in 
frequenting  these  parts.  Lastly,  the  Red  Sea,  which  does  not  throughout 
its  immense  circumference  receive  a  single  permanent  stream  flowing  on 
the  surface  of  the  ground,  nevertheless  receives  some  which  spring  from 
the  bottom  of  its  bed.  The  shores  of  the  United  States,  the  calcareous 
soil  of  which  is  probably  pierced  with  caverns  from  the  very  centre  of  the 
continent,  perhaps  are  the  coasts  which  pour  into  the  sea  the  most  abun- 
dant subterranean  rivers.  Near  the  mouth  of  the  stream  of  St.  John,  a 
submarine  stream  of  perfectly  pure  water  spouts  in  bubbles  as  far  as  one 
to  two  yards  above  the  level  of  the  sea.  Off  the  Carolinas,  and  Florida, 
salt  water  has  been  known  to  change  into  brackish  water  under  the  influ- 
ence of  the  sudden  increase  of  its  subterranean  affluents.  In  the  month 
of  January,  1857,  all  that  part  of  the  sea  which  is  adjacent  to  the  southern 
point  of  Florida  was  the  scene  of  an  immense  eruption  of  fresh  water. 
Muddy  and  yellowish  water  furrowed  the  straits,  and  myriads  of  dead  fish 
floated  on  the  surface  and  accumulated  on  the  shores.  Even  in  the  open 
sea  the  saltness  diminished  by  one  half,  and  in  some  places  the  fishermen 
drew  their  drinking-water  from  the  surface  of  the  sea  as  if  from  a  well. 
It  is  afiirraed  by  all  those  who  witnessed  this  remarkable  inundation  of 
the  subterranean  river  that,  during  more  than  a  month,  it  discharged  at 
least  as  much  water  as  the  Mississippi  itself,  and  spread  over  all  the  strait, 
31  miles  wide,  which  separates  Key  West  from  Florida.* 

On  the  coasts  of  Yucatan,  the  fresh  waters  which  take  a  subterranean 
course  down  to  the  sea  do  not  appear  to  flow  like  rivers  which  have  a 
narrow  bed  and  attain  considerable  speed,  but  more  in  the  form  of  a  wide 
sheet  of  liquid  with  a  nearly  imperceptible  current.  Cenotes  open  here 
and  there  over  the  sui-face  of  the  country ;  they  are  a  kind  of  natural 
draining-well  or  hole,  not  very  deep,  into  which  the  inhabitants  descend 
to  draw  spring  water.  At  Merida  and  in  the  environs  the  subterranean 
water  is  found  at  a  depth  of  26  to  30  feet ;  but  the  nearer  we  approach  to 
the  sea,  the  thinner  the  layer  of  rock  becomes  which  covers  the  liquid 
veins ;  on  the  sea-shore  fresh  water  is  found  nearly  on  a  level  with  the 
soil.  The  height  of  the  veins  varies  several  inches,  according  to  the  quan- 
tity of  rain ;  but  in  every  season,  the  mass  of  water  descending  from  the 
plateau  of  Yucatan  is  poured  into  the  sea  through  innumerable  outlets. 
Over  a  great  extent  of  the  shore  of  the  peninsula,  these  hidden  springs 
furnish  collectively  a  mass  sufiiciently  large  to  counterpoise  the  waters  of 
the  sea.  Under  the  pressure  of  the  marine  current  which  runs  along  the 
*  Raymond  Thomassy,  Essai  sur  Vllydrologie. 


ORIOm  OF  ''MUD-LUMFS;'  ETC.  249 

coast,  there  is  formed,  between  the  open  sea  and  the  liquid  mass  which 
has  made  its  way  from  the  land,  a  littoral  bank  like  those  barriers  which 
the  waves  construct  before  the  mouths  of  rivers.*  This  embankment, 
which  protects  the  coasts  of  Yucatan  like  a  breakwater,  is  not  less  than 
171  miles  long,  and  is  cut  through  by  the  sea  at  two  or  three  points.  The 
channel,  which  stretches  like  a  wide  river  between  the  bank  of  alluvium 
and  the  Yucatan  coast,  is,  not  without  reason,  designated  by  the  inhabit- 
ants by  the  name  of  stream,  or  rio.\ 

Among  the  remarkable  phenomena  which  perhaps  owe  their  existence 
to  subterranean  water-courses,  we  must  mention  the  sudden  or  gradual 
appearance  of  those  hillocks  of  clay  ("  mud-lumps")  which  rise,  to  the 
great  danger  of  navigators,  either  in  the  middle  of  the  bar  of  the  Missis- 
sippi, or  in  the  immediate  vicinity.  Like  small  volcanoes  of  mud,  the 
"  mud-lumps"  generally  appear  under  the  form  of  isolated  cones,  allowing 
a  rill  of  dirty  water  to  escape  from  their  summits.  Some  of  them  are  ir- 
regular on  their  surface,  on  which  lateral  orifices  here  and  there  show 
themselves,  some  in  full  activity,  others  abandoned  by  the  springs  which 
formerly  gushed  from  them.  The  water  of  some  "  mud-lumps"  is  loaded 
with  oxide  of  iron  or  carbonate  of  lime,  which,  with  the  agglutinated 
sands,  form  hard  masses,  having  the  consistence  of  perfect  rocks.  These 
liillocks  vary  both  in  their  height  and  shape.  The  greater  part  remain 
hidden  at  the  bottom  of  the  water,  and  even  their  summits  do  not  reach 
the  level  of  the  river  or  sea ;  others  hardly  raise  their  heads  above  the 


Fig.  81.  Mnd  island  in  com 


waves ;  the  most  considerable,  however,  rise  to  a  height  of  6,  9,  or  even 
19  feet,  and  their  base  covers  an  area  of  several  acres.  M.  Thomassy  is  of 
opinion  that  the  mouths  of  the  Mississippi  probably  owe  to  one  of  these 
hillocks  the  name  of  Cabo  de  Lodo  (Mud  Cape)  which  was  given  to  them 
by  the  Spanish  pilot,  Enriques  Barroto. 

It  is  evident  that  the  "  mud-lumps"  were  not  formed  by  the  alluvium  of 
the  river,  as  several  geologists  at  first  supposed.  The  great  elevation  of 
some  of  the  mud  hillocks  above  the  flood-waters  and  tides  suflices  to  ren- 
der this  hypothesis  inadmissible.  The  sudden  way  in  which  most  of  these 
water-volcanoes  make  their  appearance,  the  anchors  of  vessels,  and  the  re- 
mains of  cargoes  which  have  been  found  on  their  surface,  their  conical 
form,  their  terminal  craters,  and  all  the  springs, "  which  seem  to  spout  out 
as  if  i^om  a  subterranean  sieve,"  indicate,  on  the  contrary,  the  existence 
of  a  subterranean  force  always  at  work  to  upheave  this  band  of  hillocks. 
Messrs.  Humphreys  and  AbbotJ  think  that  this  power  consists  in  the  dis- 

*  Vide  chapter  xliii.  t  Arthur  Schott,  Mittheilunffen  von  Petermann,  18CG. 

}  Repwt  on  the  Mississippi  River. 


250  ^^^  EAUTH. 

charge  of  hydrogen  gas  proceeding  from  the  alluvium  of  the  Mississippi. 
According  to  these  engineers,  great  masses  of  vegetable  products — trunks 
of  trees,  branches,  leaves,  and  seeds — brought  down  by  the  waters  of  the 
river,  drift  upon  the  bar ;  these  are  afterward  covered  up,  and,  as  it  were, 
imprisoned  under  a  bed  of  mud,  and,  fermenting,  produce  gases  whicli 
ultimately  distend  their  covering,  and,  puffing  it  up  into  a  multitude  of 
cones,  escape  into  the  air,  after  having  pierced  the  soil  which  held  them 
captive. 

Tliis  hypothesis  sufficiently  explains  the  upheaval  of  the  soil  and  the  ex- 
istence of  the  inflammable  gases  which  are  occasionally  discharged  from 
the  craters  of  the  "  mud-lumps,"  but  it  leaves  unexplained  why  the  mud 
poured  from  the  sides  of  the  craters  is  transformed  into  a  hard  and  com- 
pact clay,  devoid  of  vegetable  matter.  M.  Thomassy  is  of  opinion  that 
the  hillocks  of  these  bars  are  the  orifices  of  regular  artesian  wells  natural- 


Pig.sa.  "Mud-lump,  "with  bubbling  springs  at  its  summit  (southwest  passage  of  the  Mississippi). 

ly  formed  by  a  sheet  of  subterranean  water  descending  from  the  plateaux 
of  the  interior  and  flowing  below  the  Mississippi  and  the  clayey  levels  of 
Louisiana.*  However  this  may  be,  the  mode  in  which  these  mud  hillocks 
are  formed  is  well  enough  known  to  render  it  easy  to  clear  them  away 
from  the  mouths  of  the  Mississippi  and  to  protect  the  interests  of  naviga- 
tion. When  a  cone  of  clay  makes  its  appearance  on  the  bar,  a  charge  of 
powder  is  introduced  into  it  and  explodes  it.  Thus,  in  the  year  1858,  the 
southwest  passage  was  cleared  of  a  "mud-lump"  which  formed  a  consid- 
erable island ;  a  single  charge  was  sufficient  to  annihilate  the  whole.  The 
island  suddenly  sunk ;  in  its  place  a  wide  depression  was  formed,  the  cir- 
cumference of  which  resembled  that  of  a  volcanic  crater;  at  the  same  time 
an  enormous  quantity  of  hydrogen  gas  was  discharged  into  the  atmos- 
phere. 

*  Geologic  de  la  Louisiane.     Essai  sur  THijdrologie. 


SYSTEM  OF  UNDEBOBOUND  BIYERS.  251 


CHAPTER  XLm. 

SYSTEM   OF   SUBTERRANEAN   STREAMS. — JOINTS  AND   FISSURES    OF  ROCKS. — 

STALACTITES. THE   INHABITANTS    OF   CAVES. THE   MAMMOTH    CAVE. — 

CAVERNS   OF   CAENIOLA   AND   ISTRIA. 

Above  the  springs,  the  course  of  subterranean  rivulets  is  generally  in- 
dicated by  a  series  of  chasms  or  natural  wells,  which  disclose  the  stream 
beneath.  The  arches  of  caves  not  being  always  strong  enough  to  support 
the  weight  of  the  superincumbent  masses,  they  necessarily  fall  in  some 
places,  leaving  above  them  other  spaces  into  which  the  upper  beds  suc- 
cessively sink.  The  debris  of  the  ruin  is  afterward  cleared  away  by  the 
water,  or  dissolved,  atom  by  atom,  by  the  carbonic  acid  contained  in  the 
stream,  and  gradually  all  the  loose  rubbish  is  carried  away.  In  this  man- 
ner, above  the  subterranean  rivulets,  a  kind  of  well  is  formed,  which  is 
designated  in  various  countries  by  very  different  names.  They  are  called 
sinks  in  the  United  States ;  dolinas  in  Carinthia ;  catavothras  in  Greece ; 
pots^  entonnoirs,  and  creux  in  the  Jura ;  embues^  embucs^  goules,  gouilles^ 
gourgs,  gourgues^  betoirs^  bolt  tout,  anselmoirs,  emposieu,  avens,  seialets,  ra- 
gages,  garagal,  in  southern  France  ;*  swallow-holes,  sand-pipes,  sand-galls, 
etc.,  in  England. 

By  means  of  these  natural  gulfs  it  is  possible  to  reach  the  subterranean 
streams,  and  to  give  some  account  of  their  system,  which  is  exactly  like 
that  of  rivulets  and  rivers  flowing  in  the  open  air.  These  streams  also 
have  their  cascades,  their  windings,  and  their  islands ;  they  also  erode  or 
cover  with  alluvium  the  rocks  which  compose  their  bed,  and  they  are  sub- 
ject to  all  the  fluctuations  of  high  and  low  water.  The  only  important 
difference  which  superficial  waters  and  subterranean  currents  present  in 
their  phenomena  is  that  these  streams  in  some  places  fill  the  whole  section 
of  the  cave,  and  are  thus  kept  back  by  the  upper  sides,  which  compress 
the  liquid  mass.  In  fact,  the  spaces  hollowed  out  by  the  waters  in  the 
interior  of  the  earth  are  only  in  a  few  places  formed  into  regular  avenues, 
which  might  be  compared  to  our  railway  tunnels.  Throughout  its  thick- 
ness, the  rock  opposes  an  unequal  resistance  to  the  action  of  the  water,  on 
account  of  the  diversity  of  its  fissures,  its  strata,  and  its  particles.  When 
the  faults  are  numerous  and  the  strata  not  very  compact,  the  current  grad- 
ually hollows  out  vast  cavities,  the  ceilings  of  which  fall  in,  and  are  car- 
ried away  by  the  water  almost  in  single  grains.  Where  beds  of  hard 
stone  oppose  the  flow  of  the  rivulet,  all  it  has  done  during  the  course  of 
centuries  has  been  to  hew  out  one  narrow  aperture.  This  succession  of 
widenings  and  contractions,  similar  to  those  of  the  valleys  on  the  surface, 
*  Fournet,  Hydrologie  Souterraine. 


252  THE  EARTH. 

forms  a  series  of  chambers,  separated  one  from  the  other  by  partitions  of 
rock.  The  water  spreads  widely  in  large  cavities,  then,  contracting  its 
stream,  rushes  through  each  defile  as  if  through  a  sluice. 

On  account  of  these  partitions,  it  is  very  difficult,  or  even  impossible,  to 
navigate  the  course  of  subterranean  rivers  to  any  considerable  distance, 
even  at  the  time  the  water  is  low.  When  it  is  high,  the  liquid  mass,  de- 
tained by  the  partitions,  rises  to  a  very  high  level  in  the  'large  interior 
cavities,  and  often  reaches  the  roof  above.  Sometimes  when,  through  the 
clefts  of  the  rocks,  a  communication  exists  between  the  cave  and  some 
hollow  above,  the  surplus  water  from  the  subterranean  streams  makes  its 
appearance  there.  Thus  the  Recca,  which  flows  beneath  the  adjacent 
plateau  of  Trieste,  does  not  always  find  space  enough  to  flow  freely  in  its 
lower  channels,  and  Schmidl  has  seen  it  ascend  in  the  chasms  of  Trebich  to 
a  height  of  341  feet.  It  may  be  understood  that  the  pressure  of  such  a 
column  of  water  often  shatters  enormous  pieces  of  rock,  and  thus  modifies 
the  course  of  underground  streams. 

When  the  water,  impelled  by  force  of  gravitation,  seeks  a  new  bed  in 
the  cavernous  depths  of  the  earth,  and  disappears  from  its  former  channels, 
these  are  at  first  much  easier  of  access  than  they  formerly  wei'e ;  but  ere 
long,  in  most  caves,  a  new  agent  intervenes,  which  seeks  to  contract  or 
even  completely  obstruct  them.  This  agent  is  the  snow-water,  or  rain, 
which  percolates,  drop  by  drop,  through  the  enormous  filter  of  the  upper 
strata.  In  passing  through  the  calcareous  mass,  each  one  of  these  drops 
dissolves  a  certain  quantity  of  carbonate  of  lime,  which  is  afterward  set 
free  on  the  arch  or  the  sides  of  the  cave.  When  the  drop  of  water  falls, 
it  leaves  attached  to  the  stone  a  small  ring  of  a  whitish  substance ;  this  is 
the  commencement  of  a  stalactite.  Another  drop  trickles  down,  and, 
trembling  on  this  ring,  lengthens  it  slightly  by  adding  to  its  edges  a  thin 
circular  deposit  of  lime,  and  then  falls.  Thus  drop  succeeds  drop  in  an 
infinite  series,  each  depositing  the  particles  of  lime  which  it  contains,  and 
forming  ultimately  a  number  of  frail  tubes,  round  which  the  calcareous 
deposit  slowly  accumulates.  But  the  water  which  drops  from  the  stalac- 
tites has  not  yet  lost  all  the  lime  which  it  held  in  solution ;  it  still  retains 
suflScient  to  enable  it  to  elevate  the  stalagmites  and  all  the  mammillated 
concretions  which  roughen  or  cover  the  floor  of  the  grotto.  It  is  well 
known  what  fairy-like  decorations  some  cavenis  owe  to  this  continuous 
oozing  through  the  vaults  of  their  roofs.  There  are  few  sights  in  the 
world  more  astonishing  than  that  of  these  subterranean  galleries,  with 
their  dead-white  columns,  their  innumerable  pendants  ^nd  multiform 
groups,  like  veiled  statues,  all  yet  unstained  by  the  smoke  of  the  visitor's 
torch.  These  stalactite  caverns  can  only  retain  this  primitive  beauty  on 
the  condition  of  not  being  given  over  to  idle  curiosity.  But  yet  how  large 
is  the  number  of  those  vulgar  admirers  who,  under  the  pretense  of  loving 
nature,  seek  only  to  profane  her ! 

When  the  action  of  the  water  is  not  disturbed,  the  needles  and  other 
deposits  of  the  calcareous  sediment  continue  to  increase  with  considerable 


STALACTITES.— FLORA  AND  FAUNA  OF  CAVES.  253 

regulai-ity.  In  some  cases,  each  new  layer  which  is  added  to  the  concre- 
tions may  be  studied  as  a  kind  of  time-measurer,  indicating  the  date  when 
the  running  water  abandoned  the  cave.  At  length,  however,  the  soft  con- 
centric layers  disappear,  and  are  replaced  by  forms  of  a  more  or  less  crys- 
talline character ;  for  in  every  case  whers  solid  particles  exist,  subject  to 
constant  conditions  of  imbibition  by  water,  crystals  are  readily  produced.* 
Sooner  or  later,  the  stalactites,  increasing  gradually  in  a  downward  direc- 
tion, meet  and  unite  with  the  needles  rising  from  the  surface  of  the  ground, 
and,  forming  by  their  number  a  kind  of  barrier,  obstruct  the  narrower 
passages  and  close  up  the  defiles,  separating  the  cavern  into  distinct  cham- 
bers. Any  objects  which  lie  on  the  surface  of  the  ground  in  these  drip- 
ping caves  gradually  become  hidden  by  the  calcareous  concretion  which 
thickens  round  them.  Generally  speaking,  when  geologists  find  in  these 
grottoes  the  remains  of  men  or  animals — the  former  inhabitants  of  the 
mountain  caves — they  are  covered  with  a  crust  of  stone,  slowly  deposited 
by  the  dripping  water.  In  1816,  in  one  of  the  caves  of  Adelsberg,  a  skel- 
eton— probably  that  of  some  bewildered  visitor — was  discovered,  which 
the  stone  had  already  enveloped  in  a  white  shroud ;  but  these  bones  have 
now,  for  some  years,  been  firmly  fixed  in  the  thickness  of  the  rock,  added 
to,  as  it  constantly  is,  by  fresh  layers ;  indeed,  the  lateral  cave  itself  will 
soon  be  filled  up  by  stalactites,  and  will  cease  to  exist.  In  like  manner, 
the  skeletons  of  three  hundred  Cretans,  who  were  smoked  to  death  by  the 
Turks  in  1822  in  the  cave  of  Melidhoni,  are  gradually  disappearing  under 
the  incrustation  of  stone  which  has  enveloped  them  with  its  calcareous 
layers-f 

In  the  gloom  of  these  dark  recesses  there  is  still  some  little  manifesta- 
tion of  life.  Since,  however,  plants  of  a  higher  order  are  unable  to  dis- 
pense with  light,  fungi  fonn  the  only  vegetation  which  we  meet  with,  and 
even  these  growths  of  darkness  do  not  always  arrive  at  their  full  develop- 
ment ;  they  often  present  monstrous  and  anomalous  forms,  which  puzzle 
the  botanist,  and  hinder  his  attempts  at  classifying  them.  Some  fungi 
never  reach  any  further  development  than  a  mass  of  confusedly  organized 
cells ;  othei-s  grow  so  as  to  cover  a  considerable  surface.  The  Fauna,  be- 
ing more  independent  of  light  than  the  Flora,  reckons  a  much  larger  num- 
ber of  representatives  in  these  caves.  Not  only  do  these  subterranean 
cavities  sei've  as  places  of  refuge  for  various  birds,  and  as  dens  for  several 
kinds  of  beasts  of  prey,  such  as  foxes,  badgers,  hyenas,  which  carry  thither 
the  prey  which  they  have  caught  (as  our  ancestors  the  troglodytes  once 
did),  but  they  are  also  inhabited  by  several  families  of  animals  which  only 
exceptionally,  or  through  accident,  ever  emerge  from  the  depths  of  the 
caverns.  Among  the  latter  there  is  at  least  one  mammal,  a  species  of  bat,| 
which  is  found  in  the  caves  of  Istria,  the  Apennines,  and  the  Algerian 
mountains.  The  subterranean  pools  and  streams  of  Central  Europe  also 
contain  several  varieties  of  a  strange  reptile — the  Hypochtlton,  or  Proteus 

♦  Knhlmann,  Presse  Sdentijique,  1 865.  t  Perrot,  L'lle  de  Crete, 

t  Minioptenu  Srhreibenii. 


254 


THE  EARTH. 


— the  eyes  of  which,  being  useless  in  the  darkness,  are  almost  aborted. 
Insects  are  the  class  which  is  best  represented  in  these  subterranean  re- 
gions, but  none  present  those  vivid  colors  which  the  light  of  the  sun  con- 
veys to  most  of  their  congeners.  All  are  clad  in  a  dull  garb  which  l^lends 
with  the  dark  shades  of  the  rock.  The  most  curious  of  these  insects  is  a 
species  of  fly  {Phora  maculata)  which  never  uses  its  wings,  and  various 
Coleoptera  (Anophthalmus),  in  which  the  eyes  are  entirely  wanting.  Then 
follow  spiders,  centipedes,  crustaceans,  and  molluscs.  M.  Schiner,  who  has 
made  a  special  study  of  the  Fauna  of  caves,  enumerates  twenty-three  spe- 
cies of  animals  which  inhabit  the  caverns  in  the  vicinity  of  Trieste  alone; 
but  these  species  form,  doubtless,  but  a  very  small  proportion  of  the  sub- 
terranean tribes  which  live  in  the  caves  scattered  far  and  wide  over  the 
whole  earth.  It  is  said  that  the  caves  in  Kentucky  contain  a  species  of 
blind  crayfish ;  also  whitish  rats,  of  a  very  large  size ;  and  lizards,  wan- 
dering gloomily  in  this  world  of  darkness ;  and,  lastly,  a  species  of  yellow 
cricket,  which  crawls  like  a  frog,  guiding  its  course  by  means  of  enormous 
antenna. 

One  of  these  Kentucky  caves,  called  the  "  Mammoth  Cave,"  is  the  lar- 
gest which  is  at  present  known.  The  whole  of  its  extent  has  not  been 
as  yet  fully  explored,  for  it  may  be  almost  called  a  subterranean  world, 
having  a  system  of  lakes  and  rivers,  and  a  net-work  of  galleries  and  pas- 
sages without  number,  which  cross  and  recross  one  another,  going  down 
to  an  immense  depth.     From  the  chief  entrance  to  the  farther  recesses  of 


Pig.  83.  Chasms  of  Carniola. 

the  cave,  the  distance  is  reckoned  to  be  not  less  than  9^  miles,  and  the 
whole  length  of  the  two  hundred  alleys  that  have  been  traced  out  in  this 
enormous  labyrinth  is  217  miles  in  extent.     This  "Mammoth  Cave"  once 


CAVERNS  OF  CAENIOLA  AND  ISTRIA. 


255 


served  as  a  retreat  for  savage  tribes,  for  skeletons  of  men  of  an  unknown 
i*aee  have  been  found  buried  in  it  under  layers  of  stalactite. 

This  district,  which  is  the  most  remarkable  among  all  the  calcareous 
countries  of  Europe  for  its  caves,  its  subterranean  streams,  and  its  abysses, 
is  unquestionably  the  region  of  the  Carniolan  and  Istrian  Alps,  which  ex- 
tends to  the  east  of  the  Adriatic,  between  Laibach  and  Fiume.  The  whole 
surface  of  the  country,  as  in  certain  plateaux  of  the  Jura  in  France,  is  ev- 
ery where  pierced  with  deep  boat-shaped  cavities,  at  the  bottom  of  which 
the  water  forms  a  kind  of  whirlpool,  like  the  water  flowing  out  of  the  hold 
of  a  stranded  ship.  Many  mountains  are  penetrated  in  every  direction 
with  caverns  and  passages,  just  as  as  if  the  whole  rocky  mass  was  noth- 
ing more  than  an  accumulation  of  cells.  On  one  steep  cliflf-side  may  be 
noticed  all  kinds  of  perforations  at  diflerent  heights — arched  portals,  and 
orifices  of  fantastic  shape ;  on  another  thei-e  are  numbers  of  springs  of 
blue  water  gushing  from  the  caves,  or  from  the  rocks  heaped  up  at  the 
foot  of  the  cliff,  and  forming  rivulets  which  disappear  a  little  farther  on 
in  the  fissures  of  the  ground,  as  if  through  the  holes  of  a  sieve.  The  whole 
surface  of  the  plateaux,  whether  bare  or  covered  with  forests,  is  scattered 
over  with  wells,  or  funnel-shaped  holes  communicating  with  subterranean 
reservoirs.  The  geography  of  the  underground  labyrinth  of  the  Illyrian 
caves  is  as  yet  only  sketched  out,  and  yet  a  considerable  number  of  sa- 
vants^ at  the  head  of  whom  stands  M.  Schmidl,  have  devoted  many  years 
of  their  lives  to  this  study.  Thanks  to  their  investigations,  some  of  the 
passages  in  these  caverns,  especially  those  of  Lueg,  are  almost  as  well 
known  as  the  corridors  and  chambers  of  a  palace. 


Fig.  84.  Orotto  of  Lneg,  Illyrla. 

OiM}  of  the  Istiian  rivers,  the  subterranean  course  ot  which,  althougli 
still  unknown  as  regards  a  great  number  of  points,  has  given  rise  to  a 
most  continuous  course  of  investigations,  is  the  celebrated  Timavus  (Ti- 
niavo),  which  falls  into  the  sea  near  Duino,  about  twelve  miles  to  the 
north  of  Trieste.     Virgil's  description*  no  longer  applies  to  the  mouths 

*  "  Fontem  superare  Timavi 

TJnde  per  ora  novem  vasto  cum  murmure  montis 
It  mare  pra:ruptam,  et  pelago  premit  an-a  sonanti." 


256  ^^^  EARTH. 

of  the  Timavo  ;  at  present  they  do  not  reach  the  number  of  nine,  because 
either  the-  extei'mination  of  the  woods  of  the  Carso  has  diminished  the 
mass  of  the  water,  or  the  action  of  the  stream  and  the  alluvium  of  the 
delta  have  modified  the  form  of  the  shore.  But  still  it  is  a  magnificent 
spectacle  to  see  the  outlet  of  the  three  principal  torrents  of  water,  which 
rush  foaming  out  of  the  heart  of  the  rocks,  and  are  navigable  from  their 
mouths  to  their  very  source.  A  river  of  this  importance  must  certainly 
receive  the  drainage  of  a  vast  basin,  and  yet  all  the  neighboring  valleys 
seem  perfectly  devoid  of  rivulets,  and  their  surface  presents  little  else  but 
the  bare  rock ;  in  fact,  the  whole  of  the  rain  and  snow-water  runs  away 
through  underground  caverns.  We  do  not  meet  with  any  tributary  until 
we  reach  a  spot  21  miles  southeast  of  the  mouth  of  the  Timavo.  This 
tributary,  known  under  the  name  of  the  Recca,  is  lost  in  the  rock  under  a 
high  arch  on  which  stands  the  village  Sant  Canzian ;  it  appears  again  at 
the  foot  of  two  precipices,  and  then  ingulfs  itself  in  the  depth  of  the  rocks 
by  a  series  of  beautiful  cascades,  beyond  which  explorers  have  not  traced 
it.  Farther  on,  the  course  of  the  subterranean  torrent  is  only  indicated 
by  abysses  opening  here  and  there  in  the  midst  of  the  plain.  In  1841,  M. 
Lindner,  who  was  seeking  in  every  direction  for  springs  of  water  to  su]> 
ply  the  city  of  Trieste,  the  inhabitants  of  which  were  threatened  with 
drought,  formed  the  idea  of  sending  some  miners  down  into  the  chasm  of 
Trebich,  situated  about  four  miles  to  the  northeast  of  the  city.  After 
eleven  months  of  labor  the  miners  at  last  reached  the  floor  of  the  lower 
cave,  1062  feet  below  the  surface  of  the  plateau,  and  there,  in  fact,  they 
found  the  Recca  of  Sant  Canzian  flowing  at  their  feet.  The  descent  into 
this  cave  is  by  means  of  ladders,  and  it  is  thus  rendered  accessible  by  the 
Avork  of  man. 

The  most  remarkable  net-work  of  caverns  in  this  region  of  the  Alps  is 
that  which  spreads  out  from  the  southwest  to  the  northeast  across  the 
Adelsberg  group  of  mountains,  between  Fiume  and  Laibach.  The  princi- 
pal cave  is  especially  curious  on  account  of  its  size,  the  variety  of  its  cal- 
careous concretions,  and  the  torrent  which  runs  roaring  through  it ;  cer- 
tainly its  vast  compartments,  its  innumerable  white  and  rose-colored  pend- 
ants, its  abysses  wrapped  in  shade,  and  the  eternal  echo  of  its  rushing  wa- 
ter, would  produce  upon  visitors  a  much  more  striking  efiect  if  its  pro- 
prietors had  not  conceived  the  untoward  idea  of  decorating  their  property 
with  rustic  or  Chinese  bridges,  elegant  staircases,  and  pyramids  adorned 
with  sentimental  inscriptions. 

North  of  the  town  of  Adelsberg  the  traveler  passes  along  the  base  of 
a  hill  with  steep  and  bare  sides,  bringing  into  view  the  sharp  edges  of  its 
highly -pitched  calcareous  beds.  On  the  right  the  stream  of  the  Poik 
winds  peaceably  in  the  valley ;  and  then,  its  course  being  arrested  by  a 
headland,  turning  suddenly,  it  flows  into  the  interior  of  the  mountain 
through  a  kind  of  high  portal,  opening  between  two  parallel  beds  of  rocks. 
Unless  the  water  in  the  stream  is  very  low,  it  is  impossible  to  follow  it 
over  the  accumulation  of  rocks  upon  its  bed ;  but  on  the  right,  at  a  height 


QROTTO  OF  ADELSBERO. 


257 


of  a  few  yards,  there  is  another  entry,  through  which  the  traveler  may  de- 
scend dry-shod  into  a  vast  cavity  or  chamber,  where  the  Poik  again  ap- 
pears issuing  from  its  narrow  passage  of  rocks.  At  this  point  the  cave 
divides ;  on  the  north  the  stream,  the  depth  of  which  varies,  according  to 


Fig.  85.  Grotto  of  Adelsberg. 

the  season,  from  a  few  inches  to  30  or  33  feet,  buries  itself  in  a  winding 
avenue,  which  has  been  traversed  in  a  boat  as  far  as  a  point  1027  yards  from 
the  entrance ;  on  the  northeast,  a  higher  avenue,  discovered  only  in  1818, 
pushes  its  way  far  into  the  heart  of  the  mountain,  branching  out  in  vari- 
ous directions,  into  narrow  passages  and  wide  compartments.  This  por- 
tion of  the  grotto,  which  appears  to  have  been  the  former  bed  of  the  Poik, 
is  the  most  curious  part  of  the  Adelsberg  labyrinth ;  it  affords  wonderful 
groups  of  stalactites,  especially  in  the  Salle  du  Calvaire,  the  vaulted  roof 
of  which,  having  the  enormous  span  of  210  yards,  has  dropped  upon  a  hil- 
lock of  debris  a  perfect  forest  of  stalagmitic  columns  and  white  needles. 

R 


258  ^^^  EARTH. 

The  full  length  of  the  principal  cave  is  not  less  than  2575  yards;  but  very 
probably  some  other  and  still  longer  avenues  may  yet  be  discovered. 

Although  it  is  impossible  to  go  in  a  boat  along  the  subterranean  por- 
tion of  the  Poik  for  a  greater  distance  than  1027  yards,  by  traversing  the 
surface  of  the  calcareous  plateaux  we  can  at  all  events  trace  out  the  sub- 
terranean stream  by  means  of  the  funnel-shaped  hoks  which  open  above 
its  course.  One  of  these  gulfs,  the  Piuka-Jama,  is  situated  about  a  mile 
and  a  half  to  the  north  of  the  entrance  of  the  Adelsberg  caves;  the  only 
way  to  descend  into  this  is  by  clinging  to  the  branches  of  the  shrubs  and 
sliding  down  by  the  assistance  of  a  cord  fastened  to  the  top  of  the  rocks. 
By  these  means  the  entrance  to  a  kind  of  air-hole  may  be  reached,  from 
which  the  Poik  is  visible  foaming  over  its  bed  of  rocks,  and  only  a  slope 
of  debris  is  to  be  descended  to  reach  the  edge  of  the  stream.  .  It  can  only 
be  followed  in  the  down-stream  direction  for  about  275  yards;  but  it  can 
easily  be  ascended  for  a  distance  of  495  yards  by  passing  under  a  high 
portal  with  lofty  pillars,  and  in  this  way  a  point  can  be  reached  which  is 
less  than  a  mile  from  the  place  where  the  stream  disappeared  in  the  cave 
of  Adelsberg. 

Farther  down  the  stream  the  Poik  is  not  visible  again  until  it  emerges 
from  the  mountain,  where  it  is  known  under  the  name  of  the  Planina ;  it 
rushes  out  through  a  circular  arch  at  the  base  of  a  perpendicular  blufT 
crowned  with  fir-trees.  It  really  is  the  Poik,  as  is  proved  by  the  equal 
temperature  of  water  and  the  sudden  increase  of  its  liquid  mass  after  a 
storm  has  burst  at  Adelsberg ;  but  the  stream  always  issues  from  the  cave 
much  more  considerable  in  bulk  than  it  is  when  it  enters,  owing  to  the 
tributaries  which  pour  into  it  on  both  sides  during  its  subterranean  course 
of  five  to  six  miles.  One  of  these  rivulets,  which  comes  down  from  the 
plateaux  of  Kaltenfeld,  joins  the  Poik  at  a  little  distance  from  its  outlet. 
Above  the  confluence  the  principal  stream  can  be  ascended  in  a  boat  to  a 
distance  of  more  than  3500  yards,  which,  with  the  other  explored  parts  of 
the  subterranean  river,  makes  about  three  miles.  Below  the  point  of  out- 
let the  stream  is  partially  lost  in  the  fissures  of  its  bed,  and  then,  joining 
the  Unz,  goes  on  and  empties  itself  into  the  Danubian  Save. 

About  a  dozen  miles  to  the  southeast  of  the  Adelsberg  and  Planina 
caves  extends  a  large  plain  surrounded  on  all  sides  by  high  calcareous 
cliffs,  at  the  base  of  which  nestle  seven  villages.  In  this  hollow,  the  most 
elevated  portion  of  which  is  under  cultivation,  the  remainder  being  cov- 
ered with  rushes  and  other  marsh  plants,  there  are  to  be  found  more  than 
400  funnel-shaped  holes  resembling  those  in  other  parts  of  Carniola. 
These  dolinas,  the  average  depth  of  which  is  from  40  to  60  feet,  have  each 
their  special  name,  such  as  the  "  Grand  Crible^''  (great  siev.e),  the  "  Crible- 
d-fromenC  (corn  sieve),  the  '"'■  Tambour'''  (drum),  the  "  Cwwe"  (tub),  the 
'"'■TonneaiC  (cask),  pointing  out  the  form  or  some  remarkable  peculiarity 
of  each  abyss.  During  extremely  dry  seasons  there  is  only  one  of  these 
cavities  which  contains  any  water ;  but  after  continuous  and  heavy  rain, 
the  water  of  a  stream  which  is  swallowed  up  in  the  rocks  a  little  above 


TRE  LAKE  OF  JESSERO. 


259 


the  plain  rises  with  a  roaring  noise  in  each  of  these  wells.  Torrents  es- 
caping from  all  these  open  "  cribles"  form  in  the  wicje  space  hemmed  in  by 
the  clTft's  a  sea  of  blue  and  transparent  water.  This  is  the  lake  of  Jessero 
or  Zirknitz,  the  lacus  Lugem  of  the  Romans.     The  surface  of  the  sheet  of 


Fig.  b4K  Urullu  urPluuiua. 


water  extends  over  an  area  of  14,826  acres;  at  the  time  of  great  inunda- 
tions, this  extraordinary  temporary  lake,  thus  vomited  out  by  the  under- 
ground river,  is  not  less  than  24,711  acres.     The  water  runs  away  through 


260  ^^^  EARTH. 

'  f 

a  subterranean  channel,  and,  further  on,  empties  itself  into  the  TJnz,  below 
the  Planina. 

Lacustrine  basins  of  this  sort,  first  emitted,  and  then  again  absorbed  by 
a  subterranean  water-course,  are  rather  rare ;  there  are,  however,  some 
other  remarkable  instances  of  them  in  Europe.  Thus,  in  the  Oriental 
Hartz,  in  the  midst  of  a  beautiful  spot  surrounded  by  fir-trees,  the  charm- 
ing lake  called  Bauerngraben  (Peasants'  Ditch),  or  sometimes  Hungersee 
(Lake  of  Famine),  sometimes  makes  its  appearance ;  but  when  this  mass 
of  blue  water  has  filled  but  for  a  few  days  its  basin  of  gypsum  rock,  it  is 
suddenly  swallowed  up,  and  flows  away  by  subterranean  channels  into 
the  stream  of  the  Helme.  The  celebrated  lake  of  Copals,  in  Boeotia,  may 
likewise  be  compared  to  the  Zirknitz  lake,  at  least  as  regards  certain  por- 
tions of  its  basin. 


NAMES  OF  WATER-COURSES.  261 


CHAPTER  XLIV. 

RIVERS. — VARIOUS    DENOMIXATIONS    OF   WATER-COURSES. — DETERMINATION 

OF  THE  PRINCIPAL  BRANCH  AMONG  THE  AFFLUENTS  OF  A  RIVER. RIVER 

BASINS   AND   WATERSHEDS. — FORKS   OF   CERTAIN   RIVERS. 

Geographers  have  long  discussed,  and  are  still  drscussing,  the  precise 
import  of  the  names  which  are  used  to  designate  running  waters.  How 
are  we  to  lay  down  any  distinction  between  a  river  and  a  stream,  or  be- 
tween a  stream  and  a  rivulet  ?  Obviously  no  absolute  difference  can  ex- 
ist, as  all  water-courses  are  alike  composed  of  liquid  masses  impelled  by 
their  own  weight  over  an  inclined  bed.  The  only  relative  difference 
which  at  first  sight  it  seems  easy  to  establish  consists  in  the  greater  or 
less  quantity  of  water  which  each  bed  contains ;  but  even  this  mode  of 
estimation  must  vary  in  every  continent  and  in  every  country,  according 
to  the  importance  of  its  hydrographical  system.  Many  a  European  river 
would  seem  nothing  but  a  slender  rivulet,  and  would  scarcely  be  thought 
worthy  of  a  name,  if  it  were  situated  in  the  immense  basin  of  the  Ama- 
zon. Added  to  this,  the  mass  of  water  alters  its  bulk  according  to  the 
various  seasons.  Many  rivers  in  tropical  regions  which  flow  very  abun- 
dantly during  the  rains,  are  during  the  dry  season  often  entirely  dried  up, 
or  changed  into  a  series  of  pools. 

All  the  phenomena  of  nature  being  full  of  diversity,  she  has  omitted  to 
furnish  any  fixed  rule  for  the  classification  of  water-courses;  but  some 
geographers,  desiring,  at  any  rate,  to  assume  an  appearance  of  authority 
in  matters  relating  to  the  earth,  have  given  the  name  of  river  {fleuve)  to 
the  liquid  masses  which  empty  directly  into  the  ocean,  and  apply  the 
name  of  stream  {riviere)  to  mere  affluents  which  are  themselves  fed  by 
tributaries  of  the  second  order,  or  rivulets.  In  virtue  of  this  purely  scho- 
lastic distinction,  the  Argens,  the  Seudre,  and  the  Leyre  would  be  rivers, 
while  the  Tapajoz  and  the  gigantic  Madeira  would  only  have  the  right  to 
the  title  of  streams.  Our  ancestors,  the  Celts  of  Western  Europe,  who 
understood  much  more  about  nature  than  many  of  our  modern  savants^ 
employed  the  same  name  (although  vai-iously  modified  by  use)  for  distin- 
guishing water-courses  of  all  sizes,  viz.,  the  Rhine,  the  Rhone,  the  Arno, 
the  Orne,  and  the  Amon.     All  running  water  was  in  their  eyes  a  river. 

The  principal  difficulty  which  systematical  geographers  meet  with  is 
that  of  determining,  as  regards  eacli  basin,  which  is  the  chief  branch;  that 
is,  which  is  to  be  considered  the  river  par  excellence^  all  the  other  water- 
courses being  mere  tributaries.  Il  some  cases,  certainly,  it  may  readily 
be  perceived  to  which  artery  of  the  river-basin  the  pre-eminence  unques- 
tionably belongs;  but  more  generally  it  is  difficult,  or  even  impossible, to 


262  ^^-^  EARTH. 

pronounce  with  any  certainty  on  this  question.  Is  it  the  Seine  or  the 
Yonne,  the  Adour  or  the  Gave-de-Pau,  the  Rhine  or  the  Aar,  the  Inn  or 
the  Danube,  the  Mississippi  or  the  Missouri,  the  Maranon  or  the  Apurimac 
(Ucayali),  which  has  the  best  right  to  impose  its  name  on  the  principal 
artery  which  bears  onward  to  the  sea  the  mingled  water  of  the  two  riv- 
ers? Does  the  point  in  question  chiefly  depend  upon  length  of  course? 
If  it  does,  the  Saone  and  the  Rhone  are  only  tributaries  of  the  Doubs, 
which  has  a  total  development,  from  Mont  Rizoux  to  the  Gulf  of  Lyons, 
exceeding  that  of  the  Rhone  by  93  miles.  In  like  manner,  the  Mississippi 
would  thus  become  a  tributary  to  the  Missouri,  which  has  a  course  more 
than  1615  miles  longer — an  excess  which  is  equal  to  three  times  the  length 
of  the  Seine.  In  deciding  which  of  the  upper  tributaries  is  the  principal 
water-course,  would  it  be  more  to  the  point  to  compare  the  quantities  of 
the  liquid  supply  which  each  brings  to  the  common  fund  ?  In  this  case, 
the  Yonne,  the  Aar,  and  the  Inn  are  rivers  which  are  fed  by  the  Seine, 
Rhine,  and  Danube  respectively.  Ought  we  not  rather  to  consider  the 
more  or  less  rectilinear  direction,  and  the  comparative  geological  unity'of 
the  valley  of  each  afiluent,  as  the  principal  signs  which  should  determine 
the  real  river?  Then  the  Rhone  and  the  Seine  are  nothing  but  seconda- 
ry water-courses  in  comparison  with  the  Saone  and  the  Yonne,  and  the 
Yonne  itself  must  yield  its  pre-eminence  to  the  Cure. 

The  savant  who  devotes  himself  to  the  unthankful  task  of  seeking  out 
the  principal  branch  in  a  river  system  has  therefore  to  take  account  of 
the  most  diversified  points  of  detail :  the  average  mass  of  water,  the  length 
of  the  course,  the  general  direction  of  the  valley,  and  the  geological  nature 
of  the  soil;  but,  whatever  may  be  the  result  of  his  investigations,  he  must 
ultimately  yield  to  the  all-powerful  authority  of  tradition.  For  it  is  tra- 
dition, and  not  science,  which  has  invested  rivers  with  their  titles  and  dig- 
nity;  it  is  the  voice  of  our  ancestors,  founded  on  a  thousand  circumstances 
in  connection  with  mythology,  the  history  of  conquests  or  colonization, 
agriculture,  navigation,  or  even  on  various  natural  phenomena,  which  has 
arbitrarily  decided  to  give  the  pre-eminence  to  some  particular  water- 
course over  the  other  rivers  of  the  same  system.  It  is  now  too  late  to  try 
to  change  the  hydrographical  nomenclature. 

But,  even  were  it  possible,  this  alteration  would  be  almost  entirely  inef- 
ficient, for  the  vitality  of  nature  will  not  accommodate  itself  to  the  strict 
classifications  to  which  pedants  would  seek  to  restrict  it.  It  is  only  by 
pure  abstraction  that,  we  come  to  consider  a  river  as  an  isolated  existence. 
In  reality,  it  is  the  aggregate  of  the  streams  and  rivulets  which  flow  into 
it  from  all  the  points  of  its  basin ;  it  unites  the  millions  of  rills  which  are 
set  free  from  the  ice,  or  trickle  from  the  crevices  of  the  rocks ;  it  is  made 
up  of  the  innumerable  springs  which  ooze  out  from  the  ground  saturated 
with  rain  or  covered  with  snow.  A  river  is  in  a  constant  process  of 
change,  and  every  tributary  takes  its  sttfcre  in  this  work  of  transformation. 
The  entire  drainage  area,  and  not  any  particular  affluent,  ought,  therefore, 
to  be  considered  as  the  real  river.     "We  must  take  into  account  the  Mis- 


ORIGIN  OF  NAMES  OF  RIVERS.— RIVEB  SYSTEMS.  263 

souri,  the  Ohio,  and  the  Red  River,  no  less  than  the  Mississippi,  extending 
its  long  and  constantly  increasing  peninsula  of  mud  into  the  Gulf  of  Mex- 
ico ;  also  the  Tapajoz,  the  Rio  Negro,  and  the  Madeira,  flowing  with  the 
Solimoes  into  the  vast  estuary  of  the  Amazon.  In  like  manner,  to  use  the 
language  of  the  sailors  of  the  Bay  of  Biscay,  the  "  two  seas"  of  Garonne 
and  Dordogne  unite  their  waters  to  compose  the  "  Sea"  of  Gironde. 

Those  names  of  rivers  which  are  formed  by  the  contraction  of  the  desig- 
nations of  their  chief  tributaries  are,  indeed,  the  only  terms  which  are  geo- 
graphically correct.  We  may  mention,  as  examples,  the  names  of  the 
Somme-Soude,  the  Thames  (Thame,  Isis),  the  stream  of  Gyronde  (Gyr, 
Onde)  in  the  Upper  Alpife,  and,  better  still,  that  of  the  Virginian  river  Mat- 
tapony  (Mat,  Ta,  Po,  Ny).  The  aggregate  of  the  arteries  of  a  river  system 
may  be  compared  to  the  branches  and  twigs  of  an  immense  tree.  The 
Rhine  and  the  Mississippi  remind  one  of  the  oak  by  the  majesty  of  their 
shape  and  the  magnitude  of  their  branches,  thrown  out  at  right  angle&  to 
the  parent  stem.  The  Nile,  with  its  long  trunk  devoid  of  lower  boughs, 
and  crowned  with  its  plume-like  terminal  branches,  recalls  to  our  mind 
the  palm-tree  of  the  oasis.  These  comparisons,  it  is  true,  have  no  scientific 
element  in  them,  but  still  they  do  not  fail  to  present  themselves  to  the 
eye,  and  geographers,  as  well  as  artists,  must  be  to  some  extent  struck  by 
them. 

Almost  all  those  portions  of  continents  on  which  the  humidity  of  the 
atmosphere  falls  in  the  shape  of  snow  and  rain  have  their  system  of  rivere, 
into  which  all  the  water  is  emptied  which  is  not,  immediately  after  its  fall, 
absorbed  by  the  earth  or  sucked  up  by  the  roots  of  plants.  But  when  the 
surface  of  the  ground  is  almost  or  quite  horizontal,  the  rain-water  can  not 
find  a  sufficient  amount  of  slope  to  enable  it  to  flow  down  toward  the  sea, 
and  consequently  spreads  out  in  stagnant  pools.  Thus,  in  the  pampas  of 
the  Argentine  Republic — where,  however,  the  annual  rainfall  is  greater 
than  that  of  France — the  prairies  are  dotted  over  with  lagunes  having  n(» 
outlet,  and  the  Vermejo,  the  Salado,  and  the  Pilcomayo — the  great  rivers 
descending  from  the  mountains  of  the  northwest — are  not  replenished  by 
a  single  tributary  from  the  plains  through  which  they  pass.* 

Lofty  mountain  chains,  the  peaks  of  which  tower  up  into  the  sky,  cross- 
ing the  very  tracks  of  the  clouds,  collect  in  proportion  a  much  larger 
share  of  moisture  than  the  plains,  and  consequently  give  rise  to  the  most 
abundant  streams  of  water.  Nevertheless,  as  low-lying  countries,  or  those 
possessing  a  moderately  elevated  vertical  outline,  embrace  an  area  much 
more  extended  than  that  of  mountainous  districts,  these  flat  regions  are 
the  localities  where  rivulets  spring  from  the  earth  in  the  greatest  number. 
In  a  general  way,  the  ravines  or  dells  in  the  plains  in  which  the  water  of 
river-sources  is  collected  are  representations  in  miniature  of  the  deep 
gorges  and  the  hollows  of  erosion  existing  in  high  mountains.  But  among 
the  incipient  river  afliuents  there  are  some  which  take  their  rise  on  level 
plateaux,  or  in  some  trifling  depression  of  the  ground ;  there  are  others, 
*  Martin  de  Moussy,  Confederation  Argentine. 


264 


THE  EARTH. 


especially  in  the  great  plains  of  Russia,  which  issue  from  lakes  or  marshes, 
which  spread  out  in  vast  sheets  in  the  centre  of  the  country.  Thus  the 
watershed — that  is,  a  ridge  separating  two  slopes,  or  perhaps  a  mere  ideal 
winding  line,  on  each  side  of  which  the  water  flows  in  an  opposite  direc- 
tion— is  developed  under  the  most  diversified  conditions.  A  river  basin 
— that  is,  the  area  which  is  traversed  by  all  its  afiluents — may  be  bounded 
on  one  side  by  the  jagged  ridge  of  some  mountain  chain,  on  the  other  by 
the  gentle  undulations  of  a  range  of  hills,  further  on  by  an  almost  imper- 
ceptible rising  in  some  low-lying  plain.  In  certain  localities,  indeed,  it  is 
necessary  to  level  the  soil  in  order  to  ascertain  the  exact  spot  where  the 
"  divorce  of  the  waters,"  as  the  ancients  used  to  call  it,  actually  takes 
place.  Added  to  this,  even  in  the  mountains,  the  ridge  line,  or  the  highest 
elevation,  is  very  far  from  uniformly  coinciding  with  the  watershed  which 
separates  two  drainage  areas.  Mountains  exhibit  such  infinite  variety  in 
their  original  form,  and  the  agents  which  denude  them  have  hollowed  out 
their  sides  in  ways  so  diversifiedj  that  some  rivers  actually  take  their  rise 
on  the  contrary  side  of  the  mountain  to  that  which  they  are  about  to  wa- 
ter. 

The  most  remarkable  instance  which  is  to  be  found  on  the  earth  of  sud- 
'  den  interruption  in  a  mountain  system  is  probably  the  astonishing  cut  of 
Riiiihue,  situated  in  the  Chilian  Andes,  near  the  fortieth  degree  of  latitude. 


Fig.  87.  Cut  of  Rinlhue,  In  the  Chilian  Andes. 


According  to  the  unanimous  evidence  of  the  aborigines  and  the  Chilian 
peasants  of  the  country,  the  stream  of  Huahuum,  which  takes  its  rise  in 
the  high  pampas  of  Buenos  Ayres,  empties  its  waters  into  the  Pacific 
after  having  crossed  the  chain  of  the  Cordilleras.  Issuing  from  the  lake 
Neltume,  the  stream  then  penetrates  into  a  defile,  where  it  is  known  under 
the  name  of  the  Caillitue.     It  is  certain  that  further  down  it  is  replenished 


BIFURCATION  OF  RIVER- COURSES. 


265 


by  a  stream  flowing  from  the  Andine  lakes  of  Panguipulli  and  Cafalquen, 
and  that  the  combined  liquid  mass  flows  on  and  empties  itself  into  the 
lake  of  Riiiihue,  which  is  a  tribiftary  of  the  Pacific  Ocean.  The  Indians 
assert  that  the  whole  extent  of  the  Huahuura  and  Caillitue  are  navigable, 
and  are  only  interrupted  by  one  single  rapid.  Unfortunately,  the  scien- 
tific explorations  of  this  region  have  not  yet  gone  beyond  the  banks  of 
the  lake  Rinihue.  It  appears  that  in  this  part  of  its  development  the  chain 
of  the  Andes  owes  its  form  to  the  action  of  the  subterranean  agents,  which 
have  raised  cones  of  eruption  at  intervals  along  the  volcanic  line  of 
fault.* 

Several  river-basins  exhibit  rather  a  curious  phenomenon.  The  water- 
shed line,  traversing  high  mountain  chains,  plateaux,  and  marshes,  and 
separating  two  hydrographical  systems,  is  interrupted  by  breaches  or  gaps, 
through  which  the  water  can  flow  out  of  one  basin  into  another.  On 
reaching  this  breach,  the  flow  of  water,  being  attracted  by  two  inclines, 
forks  out  into  two  streams  running  in  contrary  directions,  and  sometimes 
toward  two  different  seas.     Thus,  in  Columbia,  the  Upper  Orinoco  divides 


Fig.  88.  bifnrcaiion  of  the  Orinoco. 

into  two  rivers,  one  of  which  empties  into  the  Atlantic  immediately  to  the 
south  of  the  Antilles,  while  the  other,  known  by  the  name  of  the  Cassi- 
quiare,  runs  to  the  southwest  toward  the  Rio  Negro,  a  tributary  of  the 
Amazon.  The  river,  therefore,  which  collects  the  waters  of  the  upper  ba- 
sin of  the  Orinoco  is  a  tributary  of  two  seas  at  the  same  time ;  it  assists 
in  turning  the  whole  of  the  Guianas  into  a  great  island,  surrounded  on 
one  side  by  the  ocean,  on  the  other  by  a  channel  navigable  along  a  double 
incline,  having  its  summit  level  at  the  foot  of  the  high  mountain  of  Duida. 
*  Frick,  Mittheilungen  von  Petermann,  ii.,  1864. 


266  THE  EARTH. 

This  phenomenon  of  bifurcation,  which  has  been  rendered  famous  by  the 
journey  of  Humboldt  and  Bonpland,  is  also  found,  although  certainly  on  a 
less  magnificent  scale,  in  several  other  countries  of  the  earth,  some  moun- 
tainous, and  others  only  slightly  undulating.  In  some  places,  owing  to 
the  kind  of  indecision  which  is  produced  in  the  liquid  mass  by  the  double 
attraction  of  the  two  inclines,  man  has  been  enabled  to  regulate  at  his  will 
the  course  of  the  two  diverging  streams,  or  even  entirely  to  do  away  with 
the  bifurcation  by  means  of  a  dam,  or  some  other  hydraulic  works.  But 
to  make  up  for  it,  in  a  multiplicity  of  other  cases  human  ingenuity  has 
been  able  to  utilize  the  depressions  of  the  surface  so  as  to  draw  off  later- 
ally an  arm  of  a  river,  and  thus  create  an  artificial  fork.* 

In  Europe  only,  numerous  instances  may  be  mentioned  of  natural  bifur- 
cations. In  Sweden  a  small  lake,  which  is  situated  at  a  height  of  more 
than  3300  feet  at  the  foot  of  the  lofty  mountain  of  Sneehattan,  simultane- 
ously feeds  the  stream  of  Lougen,  which  descends  toward  Christiania,  and 
that  of  Romsdal,  which  empties  itself  into  the  Molde  Fjord, between  Ber- 
gen and  Trondjhem.  Added  to  this,  the  marsh  of  Kol,  on  the  plateau  of 
Hardanger,  gives  rise  to  eight  rivulets,  each  diverging  in  its  own  particu- 
lar direction.!  In  like  manner,  on  a  rocky  plateau  situated  at  a  height  of 
about  2640  feet  to  the  east  of  Puy  de  Carlitte,  in  the  Eastern  Pyrenees,  we 
find  the  little  pool  of  Las  Dous  (the  Two)  emptying  its  waters  simultane# 
ously  into  an  affluent  of  the  Tet  du  Roussillon  and  into  the  rivulet  of  An- 
goustrine,  a  tributary  of  the  S6gre  and  the  Ebro,  Central  Italy  afibrds  a 
still  more  curious  instance  of  bifurcation.  It  appears  unquestionable  that, 
at  the  time  of  the  Romans  and  during  the  first  centuries  of  the  Middle 
Ages,  the  Arno  was  divided  into  two  branches,  one  of  which  emptied  itself 
directly  into  the  sea,  while  the  other,  crossing  on  the  south  the  valley  of 
Chiana,  fell  into  the  Paglia,  a  tributary  of  the  Tiber.J  When  the  river 
Arno,  gradually  sinking  its  northern  bed,  ceased  to  flow  into  the  valley  of 
Chiana,  the  water  which  descended  from  the  lateral  ravines  in  this  almost 
horizontal  depression  flowed  to  a  very  slight  extent  on  one  side  into  the 
Tiber,  and  on  the  other  into  the  Arno ;  but  more  often  it  stagnated  in 
wretched  marshes,  which  were  a  constant  source  of  fever.  These  marshes 
have  now  disappeared,  thanks  to  the  splendid  hydraulic  works  undertaken 
since  Torricelli's  time  by  the  Tuscan  engineers  for  the  amelioration  of  the 
valley.  By  means  of  the  alluvium  brought  by  the  torrents  on  both  sides 
into  the  settling  basins,  an  artificial  watershed  has  been  created  in  the  mid- 
dle of  the  valley,  giving  the  water  two  very  percejjtible  slopes,  inclined  in 
contrary  directions.  §  One  of  the  tributaries  of  the  basin  of  the  Seine  also 
once  offered  an  instance  of  constant  bifurcation ;  at  Mceurs  the  Grand 
Morin  divides  into  two  streams,  one  of  which  flows  down  to  the  Marne, 
and  the  other  feeds  the  Superbe,  an  affluent  of  the  Seine.  But  lately,  ow- 
ing to  the  destruction  of  the  woods,  the  sources  have  become  diminished; 

*  Vide  the  chapter  on  "  The  Labors  of  Man." 

t  Fritsch,  Mittheilungen  von  Petermann,\o\.  xi.,  18fi6. 

X  Salvagnoli  Marchetti.  §  Simonin,  L^Etrurie  et  les  Etrusques. 


RIVER-BASINS  AND  WATERSHEDS. 


267 


the  double  communication  of  the  water  only  takes  place  in  an  artificial 
way  by  means  of  a  dam.* 

Among  phenomena  of  a  like  nature,  we  must  also  class  the  division  .of 
the  contents  of  a  river  into  two  branches,  which,  flowing  separately  each 
in  its  own  valley,  ultimately  reunite  at  a  considerable  distance  below  the 
point  of  bifurcation.  It  is  not  improbable  that,  at  a  recent  geological  pe- 
riod, the  Rhine  was  thus  divided  into  two  branches,  embracing  in  its 


1 

TV 

T^ 

1 » — ' 

J 

Rhin  Jk^/^"^^^"^-^ 

fe,  K 

\^^^^^ 

^S^^ 

6 

r.. 

Fig.  S9.  Bifurcation  of  the  Valleys  of  the  Rhine. 

course  an  immense  island  of  rocks  and  mountains  comprehended  between 
the  lakes  of  Wallenstadt,  Zurich,  and  Constance,  and  the  present  conflu- 
ence of  the  Aar  and  the  Rhine.  In  the  earth's  history  the  two  valleys 
may  be  looked  upon  as  having  an  equal  title  to  be  considered  the  axis  of 
the  river-basin,  as  they  have  both  served  as  the  river-bed,  either  simulta- 
neously or  in  turn.  Between  Meyenfeld  and  Sargans,  at  a  height  of  1580 
feet,  the  Rhine  doubles  round  suddenly  to  the  northeast,  and,  penetrating 
a  narrow  defile,  runs  down  to  the  Lake  of  Constance,  which  it  crosses,  and 
flows  on  to  join  the  waters  of  the  Aar  and  the  Limmat  at  about  93  miles 
below  Sargans.  The  latter  town  is  situated  on  an  isthmus  of  pebbles  and 
peat,  which  divides  the  present  bed  of  the  Rhine  from  its  former  bed, 
whicli  tends  toward  the  northwest.  If  this  isthmus,  which  is  only  about 
16  feet  high,  were  to  disappear,  the  river  would  again  divide  into  a  fork, 
and  one  of  its  arras  would  flow  on  to  empty  itself  into  the  Lake  of  Wal- 
lenstadt, and  thence  into  the  Lake  of  Zurich  and  the  valley  of  the  Aar. 
Various  hypotheses  have  been  propounded  to  explain  the  formation  of 
•  Plessier,  Formation  des  Plateaux  et  des  Valle'es  de  la  Brie. 


268 


THE  EARTH. 


this  isthmus  which  has  severed  the  river-basin  into  two  parts,  and  forced 
the  whole  body  of  the  Rhine  to  flow  into  the  Lake  of  Constance.     It  is 


i"iy.  yu.  Threshold  of  Sargans. 


probable  that  this  mass  of  pebbles  is  a  portion  of  a  slope  of  c?e5m  brought 
down  by  the  torrent  of  Seez  from  the  recesses  of  the  gorge  of  Weiss-tan- 
nen  (White  Firs),  and  deposited  at  the  outlet  of  the  lateral  valley.*  So 
long  as  the  river  was  able  to  clear  a  way  through  these  heaps  of  stones,  a 
portion  of  it  followed  its  old  course  toward  the  Lake  of  Wallenstadt ;  but, 
being  constantly  impeded  by  the  ever-growing  barrier,  it  was  ultimately 
compelled  to  open  a  new  outlet  toward  the  north. 

A  great  number  of  examples  of  this  double  flow  of  portions  of  one  mass 
of  water  toward  different  basins  are  afforded  by  low  and  marshy  plains. 
The  marshes  of  Pinsk,  in  Volhynia,  serve  as  a  common  source  to  various 
affluents  both  of  the  Vistula  and  the  Dnieper,  thus  forming  a  link  between 
the  Baltic  and  Black  Seas.  In  spring,  when  the  snow  melts,  and  toward 
the  end  of  autumn,  after  the  heavy  rains,  a  series  of  lakes,  wet  marshes, 
and  temporary  rivulets  connect  the  inland  Caspian  with  the  Sea  of  Azof 
and  the  Euxine.  The  water  of  the  Kalaous,  coming  down  from  one  of  the 
rugged  valleys  of  the  Caucasus,  divides,  and  forms  a  temporary  channel 
*  W.  Huber,  Report  of  the  Geographical  Society,  February  and  March,  1 866. 


CHANGES  IN  THE  COURSE  OF  RIVERS. 


269 


between  the  two  basins,  which  were,  indeed,  once  united  in  one  and  the 
same  ocean. 


Fii'.  91.  Marshes  of  Pinsk. 


The  two  principal  river-systems  of  North  America — those  of  the  Missis- 
sippi and  the  St.  Lawrence — are  likewise  blended  together  for  a  few  days 
after  a  prolonged  rain-fall.  Even  before  the  construction  of  the  canal 
which  at  present  unites  the  two  rivers,  small  boats  could  sometimes  pass 
from  the  Chicago  River  into  the  Illinois,  and  thus  cross  the  scarcely-indi- 
cated watershed  which  divides  the  basin  of  Newfoundland  from  that  of 
Mexico.  In  a  recent  period — that  is,  about  4500  or  5000  years  ago — the 
union  of  the  two  river-basins,  which  has  now  become  but  temporary,  ap- 
pears to  have  been  of  a  permanent  character.  The  calculations  and  ob- 
servations of  Sir  Charles  Lyell,  Schoolcraft,  and  many  American  geolo- 
gists, render  it  very  probable  that,  at  this  epoch,  all  the  upper  affluents 
of  the  Mississippi  and  the  St.  Lawrence  fed  a  lacustrine  reservoir,  the 
vast  sheet  of  which,  situated  about  600  feet  above  the  level  of  the  ocean, 
stretched  toward  the  north  as  far  as  the  mouth  of  the  Wisconsin,  and  on 
the  east  joined  the  Lake  Michigan,  covering  all  the  intervening  peninsulas. 
The  centre  of  the  continent  was  occupied  by  a  sea  as  large  as  our  Medi- 
ten-anean,  which  emptied  itself  into  the  ocean  by  an  immense  delta,  each 
arm  of  which  was  one  of  the  greatest  rivers  of  the  earth.* 

The  bifurcations  of  water-courses  do  not,  however,  all  take  place  on  the 
surface  of  the  ground ;  and  if  the  deeper  layers  coiild  be  disclosed  to  our 
view,  it  is  probable  that  we  should  find  the  majority  of  river-basins  would 
afford' instances  of  subterranean  derivations.  In  a  country  like  France,  in 
which  geological  exploration  has  seriously  commenced,  a  considerable 
number  of  these  curious  phenomena  have  been  discovered,  although  they 
♦  Humphreys  and  Abbot,  Report  on  the  Mississippi  River. 


270 


THE  EARTH. 


Fig.  92.  The  Ponto-Caspian  Isthmus. 

4 

are  in  general  but  little  noticed.  Thus,  in  the  Basses  Pyrenees,  the  Gave 
d'Ossau  forms  a  fork  at  the  foot  of  the  high  hill  of  the  Sevignac.  One  arm, 
running  to  the  northwest,  flows  on  to  join  the  Gave  d'Aspe,  and  forms  the 
Gave  d'Oloron ;  but  the  other  buries  itself  under  the  rocks,  and  reappears 
about  five  miles  to  the  north,  in  two  very  strong  springs,  the  stream  re- 
sulting from  which,  called  the  Neez,  empties  itself  into  the  Gave  of  the 
same  name,  not  far  from  Pau.  In  like  manner,  in  the  centre  of  France, 
the  Haute-Vezere  sends  one  of  its  arms  under  the  ground,  for  a  distance 
of  about  three  miles,  to  feed  the  stream  of  the  Isle,  which  meanders  through 
its  deep  valley  in  long  parallel  windings. 


ORDERLY  DISTRIBUTION  OF  BITERS.  271 


CHAPTER  XLV. 

THE    nYDROGEAPHICAL   SYSTEMS   OF   VARIOUS   PARTS    OP   THE    WORLD. 

The  great  difference  which  exists  between  continents  as  regards  both 
their  vertical  outline  and  their  extent  of  area  gives  to  the  water-courses 
in  each  part  of  the  world  the  most  diversified  directions  and  characteris- 
tics. In  every  place  the  general  plan  of  the  hydrographical  system  va- 
ries in  proportion  to  the  height  and  bearing  of  the  mountain  chains,  the 
length  and  inclination  of  their  slopes,  the  geological  nature  of  the  regions 
which  it  waters,  and  the  annual  quantity  and  distribution  of  the  rain-fall. 
But,  since  the  continental  masses,  both  in  their  general  outline  and  in 
their  different  parts,  present  an  evident  equipoise  in  their  forms ;  since 
the  clouds  and  winds  are  in  full  obedience  to  constant  laws ;  the  result  is, 
that  the  rivers  themselves  are  arranged  on  the  surface  of  the  earth  with 
a  remarkable  degree  of  order,  which  is  all  the  more  beautiful  in  that  it  so 
considerably  deviates  from  any  symmetrical  regularity.  The  graceful 
windings  of  a  river,  its  long  and  almost  quivering  curves,  and  the  intri- 
cate bends  of  its  innumerable  tributaries,  prevent  our  noticing  the  rhythm 
of  its  system,  and  how  this  system  prevails  from  one  end  of  the  world  to 
the  other.  On  our  earth  physi«al  laws  are  but  rarely  manifested  in  all 
their  inflexible  simplicity.  Owing  to  the  vitality  which  pervades  every 
thing,  they  often  assume  a  character  of  beauty,  and  through  this  very 
beauty  they  not  unfrequently  evade  the  notice  of  man. 

A  study  of  the  map,  with  regard  to  the  distribution  of  rivers  over  the 
surface  of  the  earth,  brings  before  our  view,  at  a  glance,  this  fact — that 
the  watei'-courses  which  are  tributaries  of  the  Atlantic  exceed  consider- 
ably, both  in  number  and  importance,  those  which  belong  to  the  great 
Pacific  Ocean.  This  sea,  the  greatest  of  all  seas,  receives  directly  only 
five  considerable  rivers — the  Cambodin,  the  Yantse-kiang,  the  Hoang-ho, 
the  Amoor,  and  the  Columbia ;  but  the  comparatively  narrow  channel  of 
the  Atlantic  is  the  reservoir  into  which  the  most  enormous  rivers  of  the 
earth  pour  their  contents — the  Uruguay  and  the  Parana,  the  River  of 
the  Amazons,  the  Orinoco,  the  Mississippi,  and  the  St.  Lawrence,  without 
reckoning  the  Congo,  Niger,  and  Gambia,  all  the  water-courses  of  West- 
ern Europe,  and,  by  the  intervention  of  the  Mediterranean,  the  Nile  and 
the  Danube — the  two  great  rivers  of  the  ancients.  This  unequal  distri- 
bution of  rivers  is  a  result  of  the  semicircular  arrangement  of  the  Andes, 
the  Californian  mountains,  and  those  of  Kamtschatka  and  Siberia,  all 
round  the  basin  of  the  Pacific.  The  western  side  of  South  America  is 
excessively  poor  in  rivers.  All  over  this  narrow  belt,  which  is  on  the 
average  not  one  tenth  as  wide  as  the  opposite  Atlantic  side,  and  is,  be- 


272  '^^^  EARTH. 

sides,  rarely  visited  with  rain,  there  are  at  most  but  two  or  three  rivers 
which  are  navigable.  The  streams  of  Chili  and  Western  Columbia  would 
scarcely  merit  the  name  of  rivulets  in  the  basin  of  the  gigantic  Marauon. 

In  a  hydrographical  point  of  view,  the  continent  of  Asia  may  be  di- 
vided into  three  entirely  di||||nct  systems — those  of  the  north,  the  centre, 
and  the  south.  The  first  is  the  great  plain  of  Siberia,  which  is  gently  in- 
clined toward  the  Frozen  Ocean,  and  the  whole  extent  of  which  is  crossed 
by  three  parallel  rivers,  certainly  among  the  largest,  but  also,  perhaps, 
the  least  used  by  man,  of  all  the  water-courses  in  the  world.  In  the  cen- 
tre of  the  continent  there  are  several  closed  basins,  consisting  of  plateaux 
more  or  less  desert,  the  streams  of  which  are  lost  in  some  lake,  or  evap- 
orate during  their  course.  The  southern  and  eastern  countries  of  Asia 
are  the  portions  of  the  continent  which  show  a  genuine  vitality — thanks 
to  the  sea  which  bathes  them,  the  deeply  indented  shape  of  their  penin- 
sulas, the  varied  productions  of  their  soil,  and,  above  all,  to  the  numerous 
water-courses  which  traverse  them. 

The  most  remarkable  of  these  rivers  are  arranged  in  pairs,  so  as  to 
constitute  three  groups  of  twin  currents.  These  are  the  Tigris  and  Eu- 
phrates, the  Ganges  and  Brahmapootra,  the  Yantse-kiang  and  Hoang-ho. 
In  each  of  these  pairs,  the  two  rivers  take  their  rise  side  by  side  in  the 
bosom  of  the  same  system  of  mountains,  and,  bending  their  course  in  op- 
posite directions,  each  describes  a  vast  semicircular  line  all  across  the 
continent,  and  ultimately  again  unite  before  they  empty  themselves  into 
the  sea  through  the  same  delta.  There  is  another  point  which  still  far- 
ther augments  the  analogy  between  these  double  fluviatile  arteries,  viz., 
that  each  empties  its  waters  into  one  of  the  three  seas  situated  to  the 
east  of  the  three  southern  peninsulas  of  Asia.  The  Shat-el-Arab  flows 
into  the  Persian  Gulf,  to  the  east  of  Arabia ;  the  Ganges  into  the  Bay  of 
Bengal,  to  the  east  of  India ;  the  Chinese  rivers  into  the  Pacific  Ocean, 
which  stretches  to  the  north  and  east  of  the  Indo-Chinese  peninsula. 

In  order  to  understand  the  general  features  of  the  river-system  of  the 
Asiatic  continent,  there  is  a  fourth  group  of  allied  rivers  which  we  must 
also  notice — the  Indus-Sutlej.  Certainly  these  two  rivers  of  the  western 
regions  of  Ilindostan  unite  their  waters  at  a  rather  considerable  distance 
from  their  mouth ;  but  their  lower  course  has  entirely  the  character  of  a 
delta.  The  Indus  and  the  Sutlej  were  probably  once  separated,  and  be- 
came united  in  consequence  of  the, alteration  of  their  course,  and  the  con- 
siderable elongation  of  the  delta  common  to  both  which  received  their 
alluvium.  In  like  manner,  at  the  time  of  Alexander  the  Great,  the  mouths 
of  the  Tigris  and  Euphrates  were  situated  at  a  good  day's  march  from 
each  other;  but  at  the  present  day  the  two  river-arms  coalesce  at  some 
considerable  distance  from  the  sea,  and  form  together  the  Shat-el-Arab, 
The  Indus  and  the  Sutlej  may,  therefore,  be  classed  among  the  double 
rivers,  as  their  sources  lie  very  close  to  one  another;  their  courses  take 
an  entirely  different  direction,  and  they  also  have  a  common  outlet.  As 
the  waters  of  this  fourth  group  of  rivers  descend  from  the  same  mountain 


DIVERSITY  OF  RIVER-SYSTEMS.  273 

range  which  gives  rise  to  the  Ganges  and  the  Brahmapootra,  we  might 
even  say  that  in  the  north  of  Hindostan  there  is  a  double  system  of  al- 
lied rivers  which  at  their  sources  are  almost  joined.  The  four  most  con- 
siderable currents  of  water  in  India,  taking  their  departure  from  nearly 
the  same  point,  flow  away  in  opposite  directions,  and,  after  describing 
enormous  circuits,  unite  in  pairs,  as  if  to  obey  some  double  law  of  har- 
mony and  contrast — the  Indus  and  the  Sutlej  to  the  east,  the  Ganges  and 
the  Brahmapootra  to  the  west.  They  are  the  four  animals  of  the  Indian 
legend  —  the  elephant,  the  stag,  the  cow,  and  the  tiger  —  which  spring 
down  from  the  same  mountain  peak  into  the  green  plains  of  Hindostan. 

The  contrast  offered  by  Europe  proper — so  rich  in  mountains,  peninsu- 
las, and  deep  indentations  of  the  coast — to  the  vast  plain  of  an  almost 
Asiatic  character  which  distinguishes  Eastern  Europe,  shows  itself  equal- 
ly in  the  river-systems  of  the  two  halves  of  the  continent.  In  Western 
Europe  the  Alps  and  the  other  chains  of  mountains  radiating  from  them 
determine  the  characteristics  of  the  water-system.  In  the  Sclavonic 
countries,  inhabited  as  they  are  by  peoples  hardly  emerged  from  barba- 
rism, the  great  rivers,  such  as  the  Volga,  the  southern  Dwina,  the  Nienien, 
the  Bug,  and  the  Dnifeper,  all  take  their  rise  in  the  marshy  or  slightly 
undulating  regions  which  occupy  the  interior  of  Russia.  Certainly  they 
roll  down  a  very  considerable  mass  of  water ;  but  in  their  historical  im- 
portance they  are  very  inferior  to  the  rivers  which  spring  from  the  Alps, 
and,  flowing  in  every  direction,  water  the  various  countries  of  Western 
Europe — the  principal  theatre  of  modern  civilization.  The  Alpine  group 
of  streams  is  that  to  which  it  is  chiefly  material  to  devote  a  separate 
study.  From  the  sides  of  the  St.  Gothard,  the  centre  of  the  Alps,  three 
rivers,  not  counting  the  Reuss,  take  their  rise — the  Rhine,  the  Rhone,  and 
the  Tessin — falling  respectively  into  the  North  Sea,  the  Mediterranean, 
and  the  Gulf  of  Venice.  Two  other  water- courses,  which  do  not  pre- 
cisely descend  from  the  St.  Gothard  itself,  take  their  rise  in  its  vicinity. 
These  are  the  Aar,  the  pi-incip£U  tributary  of  the  Rhine,  and  the  Inn,  a 
stream  more  important  than  the  Danube — the  name  which  it  assumes  be-» 
low  the  point  of  their  confluence.  Here,  then,  are  five  rivers  which  radi- 
ate toward  four  seas  from  one  single  group  of  the  Alps ;  but  as  isolated 
rivers,  and  not  in  the  form  of.  double  systems,  like  those  of  India  and 
China.  However,  these  distinct  water-courses,  especially  the  Rhone  and 
the  Rhine,  present  some  remarkable  peculiarities.  These  two  great  rii^ 
ers,  nearly  equal  in  volume,  flow  each  in  a  diametrically  opposite  dirfil^ 
tion ;  then,  turning  suddenly  toward  the  north  by  an  abrupt  bend,  and 
crossing  a  lake  of  considerable  dimensions — one  the  Lake  of  Geneva,  the 
other  the  Lake  of  Constance — cross  the  parallel  chains  of  the  Jura  either 
in  rapids  or  cataracts,  and,  finally  emerging  from  the  mountainous  regions, 
flow,  the  one  directly  to  the  north,  toward  the  German  Ocean,  the  other 
directly  to  the  south,  toward  the  Mediterranean.* 

Other  groups  of  the  same  mountain  chain,  such  as  those  of  the  Viso 
*  W.  Huber,  Bulletin  de  la  Societe  de  Giographie,  18G6. 
S 


274 


THE  EARTH. 


and  the  Levanna,  near  Mont  Cenis,  form  secondary  centres  for  the  radia- 
tion of  streams ;  but,  as  regards  their  hydrographical  importance,  none 
of  them  can  be  compared  to  the  central  group  of  the  St.  Gothard. 

The  great  rivers  of  peninsular  Europe  which  are  not  fed  by  the  Alpine 
snows  flow  to  the  north  of  the  almost  continuous  line  of  mountains  which 
is  formed  across  the  continent  by  the  chains  of  the  Pyrenees,  the  Ce- 
vennes,  the  Jura,  the  Alps,  and  the  Carpathians.  The  rivers  which  descend 
to  the  south  are  smaller,  on  account  of  the  more  contracted  area  which 
is  afforded  them  in  Europe  by  the  Mediterranean  slope.  But  it  must  be 
remarked  that  the  line  of  summits  does  not  exactly  mark  out  the  water- 
shed where  the  waters  divide,  some  flowing  to  the  north,  the  others  to 
the  south ;  there  is,  in  fact,  a  complete  mutual  invasion  of  the  opposite 
basins,  and  their  respective  interpenetrations  fit,  as  it  were,  one  into  the 
other.  A  river  flowing  to  the  north  receives  aflS^uents  from  the  southern 
side  of  the  mountains,  and  another  flowing  to  the  south  receives  those 
from  the  north.  Thus,  on  the  Tatra  (Carpathians)  the  water-shed  is  far 
from  coinciding  with  the  line  of  summits,  and  cuts  across  the  chain  of 
mountains.  The  Arva,  coming  from  the  north,  penetrates  the  mountain- 
chain,  and  flows  on  into  the  Theiss ;  while  the  Poprat,  taking  its  rise  in 
the  south,  hollows  out  a  bed  for  itself  through  the  gorges,  and  runs  on  to 


ibterrane- 
1!  course 
of  the  Ga- 
ronne. 


Fig.  93.  Sources  of  the  Garonne. 

ioin  the  Vistula.*  In  like  manner,  the  Garonne  rises  in  the  glaciers  of 
Twe  Maladetta,  to  the  south  of  the  principal  chain  of  the  Pyrenees,  and 
makes  its  way  into  the  district  of  Aran  and  the  plains  of  France ;  but  to 
effect  this  it  is  compelled  to  cross  the  base  of  the  mountain  of  Poumero 
through  a  subterranean  gulf  4376  yards  long.  The  water,  which  disap- 
pears on  the  Spanish  side  in  the  high  valley  of  Essera,  reappears  on  the 
other  slope  of  the  mountain  at  a  point  1980  feet  lower  down.  The  rising 
spring,  the  water  of  which  thus  pierces  right  through  the  rocks  of  Poumero, 
was  once  held  sacred ;  it  is  called  the  "  Goueil  de  Joueou"  (Jupiter's  eye). 

*  Carl  Ritter. 


NORTH  AMERICAN  RIVERS.  275 

In  North  America  the  same  radiation  of  rivers  exists  as  in  Europe,  but 
it  spreads  round  three  centres,  two  of  which  are  mountain  groups,  and  the 
other  a  merely  gradual  and  imperceptible  rising  of  the  plain.  In  the  ter- 
ritory of  Idaho,  between  the  43d  and  44th  degree  of  north  latitude,  a 
great  peak  towers  up  to  a  height  of  13,779  feet,  to  which  Lieutenant  Rey- 
nolds has  given  the  name  of  "  XJnion  Peak,"  because  the  water  from  its 
melted  snows,  being  soon  increased  and  converted  into  important  rivers, 
flows  toward  the  Colorado  on  the  south,  the  Missouri  on  the  north,  and 
the  Columbia  on  the  west.*  More  to  the  south,  but  still  in  the  angle 
formed  by  the  valley  of  the  Colorado  and  those  of  the  tributaries  of  the 
Missouri,  the  Rio  Grande  del  Norte  takes  its  rise,  thus  completing  the 
system  of  radiation  of  large  rivers  round  an  elevated  group  of  the  Rocky 
Mountains.  Nine  degrees  farther  north,  in  the  vicinity  of  Murchison 
Peak,  several  of  the  more  important  springs  rise  which  feed  the  Fraser 
River,  the  Columbia,  the  Saskatchevan,  the  Athapasca,  and  the  Macken- 
zie. According  to  Antisell,  three  of  these  rivers  are  fed  by  the  snow  of 
the  same  mountain.  The  sources  of  the  Mackenzie  and  the  Columbia 
take  their  rise  at  a  distance  of  about  200  yards  from  each  other;  and  in 
fourteen  paces  or  so  a  man  may  walk  from  the  origin  of  the  Columbia  to 
that  of  the  Saskatchevan.  These,  then,  are  the  spots  whence  the  radia- 
tion takes  place  of  the  great  rivers  on  the  northwest  of  the  continent. 
The  radiating  centre  of  the  rivers  of  the  plain  is  situated  a  little  to  the 
west  of  Lake  Superior,  in  the  vicinity  of  the  Red  Lake,  Lake  Itasca,  Lake 
of  the  Woods,  and  several  sheets  of  fresh  water  which  are  scattered  over 
the  highest  part  of  the  lower  plateaux  of  North  America.  Thence  spring 
forth  the  sources  of  the  Mississippi  proper,  those  of  the  St.  Lawrence,  and 
the  Northern  Red  River,  a  tributary  of  the  great  Lake  Winnipeg,  which 
communicates  with  the  Mackenzie  River  and  the  Frozen  Ocean  by  a  se- 
ries of  sheets  of  water.  The  radiating  centre  of  the  river-system  of  the 
plains  serves  to  link  together  the  two  centres  of  the  Rocky  Mountain 
chain.     It  forms  the  complement  of  them. 

The  three  regions  of  the  American  river  sources  are  mutually  linked  to- 
gether by  the  two  principal  aflluents  of  one  Jpat  river.  Thus,  the  gigan- 
tic development  of  the  upper  branches  of  the  Mississippi  connects  the 
lofty  groups  of  the  Idaho  mountains  with  the  marshy  plains  of  the  Min- 
nesota ;  as  the  Missouri  it  is  classed  as  a  mountain  current,  and  as  the 
Upper  Mississippi  it  is  a  stream  of  the  plains.  The  river,  therefore,  which 
unites  all  these  waters  is  essentially  double  in  its  character.  The  Mac- 
kenzie River  also  presents  this  appearance  of  duality,  although  in  a  lass 
degree,  as  it  receives  affluents  both  from  the  lake  region  and  also  from 
the  chain  of  the  Rocky  Mountains.  In  like  manner,  the  two  principal 
branches  of  the  Columbia,  the  Serpent  River  and  the  Columbia  proper, 
take  their  rise  respectively  in  the  two  groups  of  summits,  whence  the 
streams  radiate  toward  various  points  of  the  continent. 

South  America  isjoar  excellence  the  country  of  rivers.  There  roll  down 
♦  Humphreys  and  Abbott,  Antisell,  etc. 


276  ^^^  EARTH. 

the  immense  Amazon,  navigable  for  more  than  3000  miles ;  the  mighty- 
Parana,  signifying  by  its  name  "  The  River"  pre-eminently ;  and  the  Ori- 
noco, surnamed  "  the  Father  of  Waters,"  the  drainage  area  of  which  is 
not  one  third  so  extensive  as  that  of  the  Mississippi,  although  the  latter 
river  pours  down  a  much  less  considerable  body  of  water.  On  account 
of  the  narrowness  of  the  Pacific  slope,  alLthe  great  water-courses  of  South 
America  flow  over  the  plains  situated  to  the  east  of  the  continent;  but 
they  do  not  all  take  their  rise  in  the  chain  of  the  Cordilleras.  The  Orino- 
co takes  its  rise  in  the  mountains  of  Guiana,  the  Maranon  in  the  Andes, 
the  Parana  and  the  greater  part  of  its  tributaries  spring  from  the  high 
plateaux  in  the  interior  of  Brazil.  These  rivers,  therefore,  do  not  radiate 
round  the  same  centre ;  on  the  contrary,  they  belong  to  two  basins  which 
are  perfectly  distinct,  and,  indeed,  cross  one  another  at  right  angles.  The 
basin  of  the  Amazon  tends,  in  fact,  from  west  to  east,  while  the  plateaux 
and  plains  in  the  middle  of  the  continent,  forming  a  basin  in  the  direction 
of  the  meridian  transversal  to  that  of  the  Amazon,  are  watered  on  the 
north  by  the  Orinoco  and  the  Rio  Negro,  on  the  south  by  the  Tapajoz, 
the  Madeira,  the  Paraguay,  and  the  Parana.  The  distinguishing  feature 
of  the  river-system  of  South  America  is  in  the  fact  that  the  three  princi- 
pal rivers  are  interwoven  by  means  of  an  almost  continuous  line  of  run- 
ning water,  which  extends  from  north  to  south — from  the  mouth  of  the 
Dragon  to  the  estuary  of  the  Plata.  More  than  half  a  century  ago  Hum- 
boldt placed  the  matter  beyond  all  doubt  that  the  Cassiquiare  empties  its 
water  both  into  the  Orinoco  and  into  the  Rio  Negro.  The  communica- 
tions between  the  Tapajoz  and  the  Paraguay  are  not  so  perfect,  but  they 
nevertheless  exist  in  several  places.  According  to  M.  de  Castelnau,  the 
proprietor  of  the  Estivado  farm  irrigates  his  garden  by  turning  the  water 
from  an  affluent  of  the  Paraguay  into  the  bed  of  the  Tapajoz,  and  makes 
the  little  channels  flow  at  his  will  toward  either  the  northern  or  southern 
side  of  the  continent.  In  like  manner,  there  is  a  stream  near  Macu  which 
at  the  time  of  inundations  is  divided  into  two  currents,  one  forming  a  part 
of  the  Plata  system,  and  the  other  belonging  to  that  of  the  Amazon. 
Farther  to  the  east,  the  Rl^truapore,  an  affluent  of  the  Madeira,  and  the 
Jauru,  a  tributary  of  the  Paraguay,  take  their  rise  in  a  plain  which  is 
periodically  inundated  during  the  rainy  season.  At  the  foot  of  the  Boli- 
vian Andes  a  similar  intermingling  of  basins  takes  place,  as  regards  the 
Marmore  and  the  Pilcomayo.  Thus,  the  Caribbean  Sea  and  the  mouth  of 
the  Orinoco  are  connected  with  the  estuary  of  the  Plata  by  a  series  of 
rivers,  streams,  and  marshes. 

The  numerous  water-courses  which  proceed  from  the  central  plateau  of 
the  continent  are  all  set  in  an  aspect  parallel  to  the  Tapajoz  and  the  Madei- 
ra. The  chief  affluents  of  the  Orinoco,  on  the  contrary,  follow  the  same  di- 
rection as  the  River  of  the  Amazons.  We  are,  therefore,  correct  in  saying 
that  the  river  system  of  South  America  comprehends  two  basins  crossing 
one  another.  The  Rio  Magdalena,  the  Atrato,  and  the  other  streams  of 
Guiana,  are  all  rivers  with  distinctly  limited  basins;  but  it  must  be  re- 


AFRICAN  JilVEJiS. 


277 


Fig.  94.  luterlacing  Baeins  of  the  Amazon  aud  the  Lii  Plata. 

marked  that  they  all  flow  from  the  south  to  the  north,  in  the  same  direc- 
tion as  the  southern  tributaries  of  the  Amazon. 

In  tliat  portion  of  the  earth  which  is  the  most  massive  and  the  least  aiv 
ticulated  in  its  shape  an  harmonious  correspondence  is  found  between  the 
water-courses  and  the  continent  itself.  As  long  as  the  greatest  part  of 
Africa  was  an  unknown  region,  geographers  were  able  to  attribute  to  its 
rivers  all  kinds  of  imaginary  courses ;  they  could,  as  their  fancy  dictated, 
make  the  Nile,  the  Niger,  and  the  Congo  take  their  rise  from  one  common 
source,  or  interweave  in  a  complete  net-work  all  the  tributaries  of  these 
great  rivers.  But  the  discoveries  of  modern  travelers  will  now  warrant 
us  in  forming  some  general  idea  of  the  African  river-systems.  This  land, 
80  devoid  as  it  is  of  peninsulas  and  of  deep  indentations  in  its  coasts,  does 
not,  probably,  present  more  than  one  centre  of  radiation  for  its  watere, 
which  centre  is  situated  about  the  middle  of  the  continent.  From  this 
point  descend  the  Chary,  the  Binue — a  tributary  of  the  Niger — various 
streams  falling  into  the  Congo,  and  some  important  affluents  of  the  Nile. 
Still,  the  principal  branches  of  the  large  rivers  take  their  rise  at  enormous 
distances  from  one  another,  and  in  the  general  features  of  their  courses 
exhibit  only  some  transient  and  slight  similarities.  The  basin  of  the  Nile 
is  partly  separated  from  that  of  the  Niger  by  a  great  depression,  the  cen- 
tre of  which  is  occupied  by  the  Lake  Tchad.  In  like  manner  several  lakes 
and  their  affluents  are  interposed  between  the  three  basins  of  the  Nile, 
the  Zambesi,  and  the  Congo  ;  lastly,  a  small  independent  inland  sea — the 
Lake  N'gami — having  its  own  special  system  of  tributaries,  fills  up  the 
space  between  the  basins  of  the  Zambesi,  the  Orange  River,  and  the  Lim- 
popo. There  is  another  point  which  distinguishes  African  rivers  from 
those  of  other  countries ;  this  is  an  absence  of  any  extent  of  ramifica- 


278  ^-2^  EARTH. 

tions.  In  this  characteristic  they  resemble  their  mother-continent — a  gi- 
gantic trunk  without  peninsular  branches.  From  Assouan  to  Rosetta,  a 
length  of  seven  degrees,  the  Nile  does  not  receive  a  single  visible  affluent ; 
nevertheless,  it  must  necessarily  be  replenished  by  several  underground 
tributaries,  for  its  liquid  mass  is  much  more  considerable  in  Egypt  than 
in  Nubia.* 

Australia  is  even  poorer  in  rivers  than  the  east  of  the  African  continent 
itself  With  the  exception  of  the  Murray,  its  affluent,  the  Darling,  and  a 
few  other  rivers  that  are  navigable  at  all  times,  the  greater  part  of  the 
water-courses  in  Australia  can  scarcely  be  said  to  exist  except  during  the 
rainy  season,  and  in  summer  their  beds  are  only  indicated  by  pools  of 
stagnant  water  at  intervals.  Their  special  characteristic  appears  to  be 
periodicity. 

The  general  features  of  the  river-systems  of  each  part  of  the  world  may 
thus  be  shortly  summed  up  : 

Northern  Asia  is  distinguished  by  rivers  of  simple  character.  In  the 
south  and  east  they  are  allied. 

Europe  is  distinguished  by  two  centres  from  which  the  streams  radiate 
— one  situated  in  the  midst  of  vast  plains,  the  other  in  the  heart  of  the 
highest  mountains  of  the  continent. 

North  America  is  characterized  by  a  radiation  of  the  rivers  from  three 
centres,  two  of  which,  being  elevated  groups  in  a  mountain  chain,  are 
linked  together  by  the  third,  occupying  a  marshy  rising  in  the  plains. 

South  America  is  characterized  by  the  crossing  of  two  mutually  trans- 
verse basins  and  the  continuous  union  of  the  river-systems. 

Africa  is  distinguished  by  the  comparative  independence  of  its  water- 
courses and  their  poverty  in  tributaries. 

Australia,  by  the  small  number  of  its  rivers  and  the  periodicity  of  their 
existence. 

The  form  of  each  continent,  and  the  phenomena  of  climate  peculiar  to 
them,  have  thus  determined  the  rise  of  rivers  which  are  modeled  on  a  par- 
ticular type  in  each  division  of  the  world.  As  all  continental  masses  dif- 
fer one  from  another,  the  circulating  system  of  each  naturally  harmonizes 
with  the  general  features  of  the  regions  which  the  running  waters  trav- 
erse and  vivify. 

*  Elia  Lombardini,  Essai  sur  VUi/drologie  du  Nil. 


THE  BIVER  AMAZON.  279 


CHAPTER  XLVL 

THE  RFVEB  OP  THE  AMAZONS. — DIVERSITY  IN  THE  CHAKACTER  OP  WATER- 
COURSES.— UNITY  OP  THE  LAW  WHICH  GOVERNS  THEM. — EQUALIZATION 
OF  THEIR   SLOPES. — UPPER,  MIDDLE,  AND   LOWER   COURSES   OP   RIVERS. 

In.  like  manner  as  the  hydrographical  systems  of  each  continent  pre- 
sent in  their  special  features  the  most  marked  contrasts,  so  the  rivers  of 
each  country  and  the  various  tributaries  of  each  river.  They  are  distin- 
guished by  the  length  of  their  system,  the  winding  of  their  course,  the 
abundance  of  their  water,  the  nature  of  the  soil  which  they  pass  through, 
the  color  and  character  of  their  alluvium,  the  general  inclination  of  their 
bed,  and  the  shape  and  number  of  their  meanderings.  Thus,  only  men- 
tioning the  basin  of  one  single  river,  we  may  reckon  among  the  tributa- 
ries of  the  Mississippi  the  Clear-water  River,  the  Mud  River,  and  the 
Blue^  Green,  Yellow,  Red,  Black,  and  White  rivers.  Names  designating 
other  physical  properties  besides  that  of  the  color  or  purity  of  the  water 
are  also  very  numerous  in  the  tributary  valleys  of  the  American  rivers. 
The  same  kind  of  names  occur  in  most  river  systems ;  and,  indeed,  noth- 
ing would  be  inore  easy  than  to  give  to  every  water-course  some  name 
relating  to  its  general  aspect,  its  characteristics,  or  some  of  the  local  cir- 
cumstances which  distinguish  it,  such  as  gulfs,  cascades,  or  defiles.  Like 
the  trees  of  a  forest,  so  also  an  infinite  diversity  is  shown  in  all  the  run- 
ning waters  which  moisten  the  surface  of  the  earth.  The  chief  cause, 
however,  for  this  infinite  variety  in  rivers  must  be  sought  for  in  the  geo- 
logical constitution  of  the  soil  through  which  they  flow.  Thus,  among 
the  old  schistose  and  gneissose  rocks,  rivers  are  more  often  characterized 
by  the  abundance  of  their  liquid  mass  and  the  winding  of  their  bed. 
In  calcareous  districts  the  water-courses  are  less  richly  supplied,  more 
rectilinear,  and  generally  bounded  on  each  side  by  steep  escarpments. 
Any  sudden  bend  in  the  course  of  a  river  usually  indicates  some  important 
modification  in  the  geological  nature  of  the  strata.  We  may  mention  as 
examples  the  elbows  of  the  Rhine  at  Basle  and  Bingen,  those  of  the 
Rhone  at  Lyons,  of  the  Danube  at  Ratisbon,of  the  Elbe  at  the  outlet  of 
Saxon  Switzerland.  In  South  America  all  the  great  rivers  flowing  into 
the  Atlantic  describe  a  broad  curve  toward  the  east  when  they  leave  the 
valleys  of  the  Andes  and  make  their  way  into  the  tertiary  formations  of 
the  continent.* 

The  river  ;t>ar  excellence^  the  glory  of  our  planet,  is  the  great  stream  of 
the  Amazons,  which,  next  to  the  great  upheaval  of  the  chain  of  the  An- 
des, forms  the  principal  feature  of  the  Columbian  continent.     This  mov- 

*  Ami  Bou^. 


280  ^^^  EARTH. 

ing  fresh-water  sea,  which  takes  its  rise  at  a  short  distance  from  the  Pa- 
cific, and  empties  itself  into  the  Atlantic  through  an  estuary  measuring 
186  miles  from  promontory  to  promontory,  serves  as  a  line  of  division  be- 
tween the  two  halves  of  South  America,  and,  like  a  visible  equator,  sepa- 
rates the  northeril  hemisphere  from  the  southern  along  a  length  of  about 
3000  miles.  Every  thing  belonging  to  this  great  central  artery  is  on  a 
colossal  scale.  In  its  immense  basin,  embracing  an  area  of  2,700,000 
square  miles,  it  collects  two  or  three  thousand  times  as  much  water  as 
the  Seine.  In  different  parts  of  its  course  this  immense  river  is  known 
under  various  names,  as  if  it  were  composed  of  distinct  streams  set  end 
to  end,  and,  together  with  its  tributaries,  its  furos ,  or  false  rivers,  its 
igarapes,  or  lateral  arms,  offers  scope  for  steam  navigation  of  more  than 
30,000  miles.  It  is  so  deep  that  sounding-lines  of  150,  200,  or  even  300 
feet,  have  failed  to  measure  its  depths,  and  frigates  can  ascend  it  for  more 
than  1000  leagues.  Its  width  is  so  great  that  in  some  places  it  is  impos- 
sible to  see  the  opposite  bank,  and  at  the  mouths  of  the  Madeira,  the 
Tapajoz,  the  Rio  Negro,  and  some  other  of  its  great  affluents,  the  distant 
horizon  closes  in  upon  the  water  just  as  in  the  open  sea.  It  is  replenished 
by  dozens  of  rivers  which  scarcely  find  their  equals  in  Europe,  and  many 
of  them,  being  yet  unexplored,  still  belong  to  the  realms  of  fable.  In 
several  places  its  banks  serve  as  limits  to  two  distinct  Faunas,  and  many 
species  of  birds  will  not  venture  to  cross  the  broad  sheet.  Like  the  sea, 
it  is  inhabited  by  cetaceans  ;  like  the  sea,  too,  it  has  its  storms,  and  dur- 
ing a  tempest  the  waves  will  rise  to  several  feet  in  height.  When  we 
sail  over  the  gray  water  of  the  estuary  at  the  mouth  of  the  river,  we  feel 
tempted  to  ask,  says  M.  Ave-Lallemant,*  whether  the  sea  itself  does  not 
owe  its  existence  to  the  enormous  tribute  which  the  rolling  current  is  in- 
cessantly bringing  down  to  it.  The  difference  in  the  motion  produced 
by  the  movement  of  the  waves  or  by  the  force  of  the  current  is  the  only 
thing  which  points  out  on  which  domain  a  voyager  is  sailing — that  of  the 
fresh  or  salt  water.  Even  in  late  years,  the  greater  part  of  the  inhab- 
itants of  the  shores  of  the  Amazon — white,  black,  or  red  men  alike — are 
in  the  habit  of  fancying  that  the  great  river  surrounds  the  whole  uni- 
verse, and  that  all  the  nations  of  the  earth  are  denizens  of  its  banks.f 

Certainly,  the  difference  is  considerable  between  the  mighty  South 
.  American  river  and  some  slender  stream ;  as,  for  instance,  the  Argens, 
which  is  crossed  by  a  bridge  with  a  single  arch,  and  can  readily  be  waded 
through  by  travelers.  But  whatever  may  be  the  comparative  impor- 
tance and  the  discrepancy  of  aspect  in  these  rivers,  they  are  none  the  less 
governed  by  the  same  laws.  The  geographer  can  describe  them  all  to- 
gether by  forming  an  outline  of  an  ideal  river,  the  course  of  which  would 
afford  the  combined  phenomena  of  all  the  streams  which  traverse  the 
globe. 

The  function  of  rivers  in  the  plan  of  nature  is  incessantly  to  renovate 

*  Reise  durch  Nord-Brasilien. 

t  Bates,  The  Naturalist  on  the  River  Amazon, 


ACTION  OF  RIVERS  ON  THE  LAND.  281 

the  surface  of  continents,  to  convey  the  life  and  the  alluvium  of  lofty 
mountains  down  to  U^e  plains  and  the  coasts  of  the  ocean.  It  has  often 
been  said  that  a  landscape  can  not  be  really  beautiful  when  it  is  destitute 
of  the  rippling  motion  of  a  lake,  or  the  presence  of  running  water.  The  fact 
is,  that  man,  whose  life  is  so  short,  and,  in  consequence,  so  restless,  has  an 
instinctive  horror  of  immobility.  To  make  him  fully  appreciate  the  vi- 
tality of  nature,  it  is  requisite  that  motion  and  sound  should  bring  it  home 
to  his  senses.  Only  by  a  course  of  long  reflection  can  he  duly  estimate 
the  long-protracted  movements  of  the  terrestrial  crust ;  he  therefore  needs 
to  view  the  rapid  bounds  of  the  water  leaping  down  in  cascade  after 
cascade,  or  the  harmonious  undulations  of  the  waves.  More  than  this,  he 
also  demands  the  contrast  between  the  stable  and  the  unstable,  between 
restlessness  and  rest.  This  is  the  cause  why  a  field  of  snow  as  far  as  the 
eye  can  reach,  a  desert  without  water,  a  sky  without  clouds,  or  a  shore- 
less ocean  fail  to  excite  in  him  any  thing  better  than  a  gloomy  or  melan- 
choly admiration.  |||^  the  presence  of  these  spectacles  man  feels  himself 
crushed,  while  in  a  narrow  valley,  with  its  streams  of  running  water,  he  is 
fully  conscious  of  his  own  vitality. 

On  our  earth,  water  is,  joar  excellence^  the  symbol  of  motion.  It  flows 
and  flows  on  forever,  without  rest  and  without  fatigue.  The  lapse  of 
centuries  can  not  dry  up  the  slender  rill  of  water  trickling  from  the  fis- 
sure of  a  rock,  and  fails  to  silence  its  soft  and  clear  murmur.  It  leaps 
down  joyously,  in  cascade  after  cascade,  to  mingle  with  the  impetuous 
torrent ;  then,  blended  with  the  calm  and  mighty  river,  it  flows  on,  and 
loses  itself  at  last  in  the  immense  and  mysterious  ocean — that  tomb  in 
which  every  water-borne  fragment  finds  a  temporary  grave  till  the  re- 
solved elements  enter  again  into  the  vast  bosom  of  nature  and  reassume 
fresh  forms  of  vitality.  Motion  is  only  another  word  for  action.  Water 
does  not  merely  flow  through  a  bed  hollowed  out  ready  for  it ;  it  is  inces- 
santly eating  away,  undermining,  corroding,  washing  away,  and  moving 
the  earth  and  the  rocks  which  hem  it  in  or  oppose  its  course.  Pebble  by 
pebble,  and  grain  by  grain,  it  is  carrying  the  mountains  into  the  sea.  Wa- 
ter, as  Pascal  says,  is  "  not  merely  a  road  in  motion,  it  is  also  a  traveling 
continental  mass  which,  in  the  centuries  of  yesterday,  was  covered  with  the 
eternal  mountain  snow,  and  will  in  the  ages  of  to-morrow  be  fixed  on  the 
sea-shore,  to  augment  the  domain  of  man."  Rivers  carry  out  the  circula- 
tion of  solid  as  well  as  of  liquid  matter;  they  are  like  the  blood,  ever-flow- 
ing life-renewers.  It  is,  then,  requisite  that  we  should  study  carefully  the 
mode  of  operation  which  rivers  adopt  in  their  renovating  action  on  the 
continents  they  traverse. 

Every  current  of  water  is  constantly  tending  to  equalize  its  slope,  to 
increase  it  where  it  is  almost  imperceptible,  and  to  diminish  it  where  it 
is  too  rapid.  The  whole  course  of  the  river,  from  its  mountain  source 
down  to  its  junction  with  the  sea,  may  be  compared  to  an  avalanche  fall- 
ing from  the  heights  of  some  snow-clad  peak.  The  masses  which  sink 
down  into  the  valleys  modify  gradually  in  their  fall  the  outline  of  the 


282 


THE  EARTH. 


cliffs.  The  projections  are  broken  down,  the  fissures  are  filled  up,  a 
gracefully  curved  slope  of  debris  abuts  against  the  jrertical  walls,  and  ex- 
tends in  a  gentle  incline  down  into  the  plain.  Owing  to  all  these  exca- 
vations and  fillings  up,  the  passage  through  which  the  avalanche  makes 
its  way  ultimately  assumes  an  outline  of  considerable  regularity.  Al- 
though less  abrupt  in  its  progress,  less  violent  in  its  effects,  and  gliding 
over  a  gentler  slope  than  the  avalanche,  still  the  river  adopts  a  very  sim- 
ilar course  of  action ;  it  clears  away  the  obstacles  before  it,  and  fills  up 
any  depressions,  appearing  as  if  it  endeavored  to  provide  for  itself  a  uni- 
form incline  down  to  the  sea. 

The  portions  of  a  river's  course  where  this  equalization  of  its  incline 
chiefly  takes  place  are  naturally  those  where  the  declivity  of  the  bed  is 


%  thmmm  11 1  i  I 


Fig.  96.  Inclination  of  the  Nile  from  Khartoum  to  Damielta. 

most  rapid,  and  where  the  waters  consequently  attain  their  highest  rate 
of  speed.  It  may  be  generally  asserted  that  those  portions  of  the  river- 
beds which  are  distinguished  by  the  most  abrupt  incline  are  also  the 
most  elevated;  for  in  almost  all  the  countries  of  the  earth  the  plains  lie 
round  the  circumference  of  the  land,  and  the  mountains  rise  far  in  the  in- 
terior. Most  rivulets  and  streams  take  their  rise  thousands  of  feet  above 
the  level  of  the  sea,  and  descend  first  through  a  very  steep  bed,  some- 
times intersected  by  precipices,  or  even  interrupted  by  lacustrine  basins. 


Fig.  9(>.  Slope  of  the  Pu,  the  Tessiu,  the  Oglio,  and  the  Miuciu. 

On  reaching  the  lower  plains,  the  running  water,  now  converted  into  a 
considerable  river  by  the  tributaries  which  have  joined  it  on  both  sides 
from  the  valleys  of  the  mountain-system,  extends  in  long  and  peaceful 
windings  across  the  more  or  less  sloping  ground  which  serves  as  a  ped- 


COUBSE&  OF  RIVERS.  283 

estal  for  the  mountain  chain.  This  is  its  middle  course,  during  which 
the  river  receives  its  principal  affluents  descending  from  other  mountain 
chains,  or  the  high  ground  which  commands  it  laterally.  Then,  below 
the  last  hills,  its  lower  course  begins ;  the  fresh  water  descends  slowly 
down  to  the  sea,  and,  not  far  from  the  mouth  of  the  river,  is  arrested  in 
its  course  twice  every  day  by  the  salt  tide  which  meets  it. 

The  Rhine  is  a  magnificent  example  of  a  river  in  which  the  three  divis- 
ions of  its  course  are  regularly  developed.*  The  upper  couree,  the  whole 
of  which  is  included  in  the  Alpine  regions,  bends  round  in  a  vast  semi- 
circle to  Laufenburg  and  Basle,  where  the  rapids  cease.  The  middle 
course,  remarkable  for  its  regularity,  rolls  on  uniformly  to  a  point  below 
Mayence,  where  the  Rhine  is  compelled  to  open  a  passage  across  the 
Odenwald  and  other  hills ;  then,  below  the  Siebengebirge,  between  two 
low  banks  of  alluvial  origin,  commences  the  lower  course,  which  ulti- 
mately terminates  in  the  muddy  estuaries  of  Holland.  But  for  one  river 
where  the  three  divisions  of  its  course  are  marked  with  so  much  distinct- 
ness, how  many  there  are  which  exhibit  no  marked  diiFerence  between 
the  various  portions  of  their  bed !  How  many  there  are,  indeed,  which 
are  even  calmer  and  less  inclined  on  the  plateaux  of  the  interior  than  in 
the  vicinity  of  the  sea !  How  many  there  are,  especially,  which — as  rep- 
resented by  some  of  their  affluents — are  entirely  rivers  of  the  plain, 
while  in  other  tributaries  which  descend  from  the  mountains  they  ex- 
hibit all  the  characteristics  of  torrents !  These  are  differences  essential 
to  the  fluviatile  system  and  to  its  geological  operations. 

*  Carl  liitter,  Europa. 


284  .  THE  EARTH. 


CHAPTER  XLVn. 

MOUNTAIN  TORRENTS. — INEQUALITIES  OF  THEIR  BEDS  AND  OF  THEIR  DIS- 
CHARGE OF  WATER. — TEMPORARY  STREAMS. — FILLING  UP  OF  LAKES. — 
EROSIONS,  GORGES,  AND   SLOPES. — ^TORRENTS   OF   THE   FRENCH   ALPS. 

The  principal  features  which  distinguish  the  mountain  torrent  from  the 
water-course  in  the  plain  is  the  irregularity  of  its  bed,  its  mode  of  action, 
its  discharge  of  water,  and  its  sedimentary  matter.  Among  the  gentler 
features  of  the  plain,  the  stream  runs  but  slowly,  and  all  the  changes  of 
slope,  curve,  and  level  take  place  in  gradual  transitions ;  but,  on  the  con- 
trary, in  narrow  winding  gorges  it  is  violent,  impulsive,  and  uncertain. 
Rocky  angles  project  abruptly  across  the  water;  the  declivity  is  inter- 
sected with  precipices ;  the  liquid  mass  poured  down  by  the  torrent  may 
sometimes  be  compared  to  that  of  a  river,  but  at  other  times  it  forms 
only  a  slender  rivulet,  or  even  dries  up  altogether.  Lastly,  most  mount- 
ain streams  are  sometimes  as  pure  as  crystal,  and  at  others  are  loaded 
with  so  large  a  quantity  of  alluvium  that  they  are  more  like  avalanches 
of  debris.  The  turns  and  twists  of  the  gorges  are  so  much  the  more  sud- 
den as  the  rocks  through  which  they  are  cut  are  higher,  harder,  and 
more  irregular  in  their  stratification  and  fissures.  The  water  dashing 
against  some  projection  springs  back  at  right  angles  on  the  opposite 
rock,  to  be  again  driven  back,  and  thus  descends  toward  the  valley  in  a 
series  of  zigzag  falls.  In  these  rugged  gorges,  where  the  pathway  seems 
suspended  from  the  ledges  of  the  opposing  clifis,  on  either  side  overhead 
may  be  seen  the  abrupt  fissures  where  the  torrent  has  cut  a  passage; 
and  not  only  is  this  mass  of  water  and  foam  incessantly  cast  from  one 
side  to  the  -other  by  the  obstacles  which  hem  it  in,  but  it  is  very  often 
temporarily  kept  back  by  the  barriers  of  debris  which  crumble  down 
across  its  course.  When  the  dam,  composed  of  stones  and  blocks  of 
rock,  affords  no  interstices  through  which  the  water  can  glide,  the  latter 
gradually  rises  in  the  form  of  a  lake,  and  then  makes  its  way  as  a  cas- 
cade over  the  wall  of  rubbish,  which  by  degrees  it  hollows  out  down  to 
the  level  of  its  olA  bed.  But  usually  the  avalanche  which  pens  back  the 
torrent  consists  of  a  mass  of  snow,  dust,  and  broken  stones ;  the  water 
kept  back  by  this  more  plastic  dam  slowly  converts  it  into  a  kind  of 
pasty  mass,  and  forces  its  way  through  a  subterranean  outlet.  In  the 
spring,  when  a  good  many  avalanches  are  falling  from  the  sides  of  the 
Alps,  it  is  curious  to  trace  the  course  of  the  torrent,  visible  here  and 
there,  in  the  gorges.  The  water  may  be  seen  diving  down  under  some 
grayish  or  dark  mass,  joining  with  its  graceful  curve  the  two  opposite 
sides  of  the  ravine.     The  entrance  of  the  gulf  forms  a  kind  of  porch  orna- 


MOUNTAIN  TORRENTS.  285 

raented  with  icicles,  down  which  the  melted  snow  trickles  or  falls  drop  by 
drop.  Above  the  torrent  which  is  roaring  in  the  depths  below,  the  mass 
oi debris  is  intersected  in  some  places  with  crevasses^  and  the  closely-packed 
snow  presents  a  bluish  edge,  like  ice ;  wells  open  in  it  at  intervals,  at  the  bot- 
tom of  which  the  foaming  waves  may  be  indistinctly  seen  careering  along. 

In  ravines  and  defiles  where  the  slope  is  uniform  the  torrent-water  af- 
fords some  degree  of  regularity  in  its  volume;  but  when  the  declivity  is 
unequal  and  broken,  and  especially  when,  as  is  the  case  in  most  of  the 
calcareous  districts,  it  is  composed  of  horizontal  layers  intersected  by 
precipices,  the  liquid  mass  is  incessantly  changing  in  width  and  depth. 
In  the  level  or  gently  inclined  portions  of  its  bed  the  water,  flowing 
slowly,  spreads  out  into  a  wide  stream,  until,  reaching  the  edge  of  the 
cliff,  it  suddenly  tumbles  over,  and,  losing  in  volume  what  it  gains  in 
speed,  seems  nothing  but  a  slender  thread  of  foam  gliding  over  the  face 
of  the  rock.  Below  the  fall  a  new  basin  opens  out,  often  hollowed  in  the 
shape  of  a  tub,  in  which  the  water,  now  to  all  appearance  unstirred  by 
the  slightest  current,  reposes  quietly  as  in  a  lake.  A  great  number  of  the 
valleys  in  the  Alps,  the  Jura,  and  all  mountainous  countries,  owe  their 
picturesque  beauty  to  this  succession  of  pools  of  quiet  water  and  graceful 
cascades.  This  series  of  gradations  constitute  the  successive  planes  of 
elevated  valleys.* 

The  variations  which  are  found  in  the  discharge  of  a  torrent  stream 
are  really  enormous,  even  in  those  mountainous  countries  where,  owing 
to  the  accumulation  of  the  winter  snow  upon  the  heights,  the  water 
never  entirely  dries  up.  During  severe  cold,  when  the  snow  above  is 
frozen  on  the  ground,  and  numbers  of  rivulets  are  converted  into  solid 
ice,  the  main  stream  of  the  valley  sends  down  only  an  inconsiderable 
liquid  volume,  and  a  traveler  may  easily  cross  it  by  jumping  from  stone 
to  stone ;  but  on  the  arrival  of  the  earliest  warm  weather,  when  the  rain 
and  the  sun,  assisted  by  the  south  wind,  melt  the  snow  and  cause  it  to 
slide  down  in  avalanches,  the  masses  of  water  which  are  discharged  into 
the  torrent  from  all  sides  change  it  into  a  formidable  river,  running  some- 
times, Surell  tells  us,  at  a  speed  of  46  feet  a  second — more  than  30  miles 
an  hour.  It  spreads  out  widely  over  its  basins,  flows  over  the  meadows, 
and  often  washes  away  farm-houses,  trees,  and  even  the  vegetable  mould. 
In  the  defiles,  on  the  contrary,  it  is  compelled  to  gain  the  requisite  space 
in  height,  as  it  can  not  find  it  in  width,  and  its  level  suddenly  rises  60, 
80,  or  even  120  feet.  All  this  may  easily  be  noticed  in  the  narrow  Ital- 
ian valley-streams  fed  by  the  snow  from  the  Mont  Blanc  and  Monte  Rosa 
groups.  The  Sesia,  the  Dora,  and  many  of  their  affluents,  before  they 
empty  into  the  plain,  pass  through  dark  gorges,  where  the  liquid  mass  of 
the  flood-water,  ten  times  deeper  than  its  width,  descends  with  the  ra- 
pidity of  an  avalanche.  Looking  forward  to  these  rushes  of  water,  the 
mountaineers,  in  many  places,  have  dug  out  their  paths  more  than  15Q 
feet  above  the  bed  of  the  torrent. 

*  See  above,  chapter  on  "  Valleys,"  p.  132. 


286 


THE  EARTH. 


PicaeCrdnoiaei    TbcdcCnibioule. 


(Quadrat 


Fig.  97.  Circle  of  the  Valley  of  Lys. 

The  Var  may  be  mentioned  as  an  instance  of  this  astonishing  fluctua- 
tion in  the  discharge  of  its  torrent-waters.  At  its  outlet,  the  liquid  mass 
of  this  river  varies  from  37  to  5240  cubic  yards  of  water  in  a  second ; 
this  difference  is  as  1  to  143,  and  the  proportion  would  be  still  larger  if 
the  fluctuations  were  measured  above  the  confluence  of  the  Vaire,  the 
Tinee  and  the  Vesubie.*  In  the  level  countries  of  Western  Europe,  the 
difference  presented  between  the  high  and  low  water  levels  is,  on  the  av- 
erage, scarcely  one  tenth  of  that  afforded  by  the  Var.  In  great  rivers, 
such  as  the  Mississippi,  the  difference  between  high  and  low  water  is  as  1 
to  4  only.  As  a  standard  of  comparison  between  the  floods  of  a  torrent 
and  those  of  a  lowland  river  in  the  same  climate,  we  may  mention  the 
Upper  Loire  and  the  Somme.  Above  Roanne,  the  basin  of  the  Upper 
Loire,  at  its  first  outlet  from  the  mountains,  comprises  an  area  of  2470 
square  miles,  and  the  stream  discharges  during  exceptional  floods  9549 
cubic  yards  of  water  a  second — rather  less  than  four  yards  for  each  mile 
of  surface.  In  its  highest  floods,  the  Somme  sends  down  117  cubic  yards 
of  water — a  quantity  which,  if  it  was  spread  over  its  drainage  area,  would 
render  the  floods  of  the  Upper  Loire  84  times  more  considerable  than 
those  of  the  Somme  ;t  and  doubtless  a  comparative  study  of  the  inun- 
dations of  all  the  water-courses  in  France  would  disclose  still  greater 

*  Villenenve  Flayosc.  t  Belgrand,  Anuales  des  Fonts  et  Chatissees,  1854. 


FLUCTUATIONS  IN  RIVERS.  287 

variations  between  the  system  of  torrents  and  that  of  the  lowland 
rivers. 

In  the  tropical  regions,  where  the  rainy  season  is  succeeded  by  the 
season  of  drought,  the  greater  part  of  the  mountain  rivers  only  run 
during  half  the  year;  they  are  alternately  considerable  rivers  and  dry 
ravines. 

Thus  some  valleys — those,  for  instance,  of  the  Sierra  Nevada  de  Santa 
Marta — exhibit  a  daily  fluctuation  in  the  discharge  of  their  streams,  ow- 
ing to  the  storms  which  the  gusts  of  the  trade-winds  rarely  fail  every 
afternoon  to  dash  against  the  heights.  In  the  evening  all  the  gorges  are 
filled  with  masses  of  raging  water,  and  the  traveler  finds  himself  com- 
pelled to  put  a  stop  to  his  journey ;  he  bivouacs  on  the  edge  of  the  river, 
and  is  lulled  to  sleep  by  the  noise  of  the  cataracts  roaring  over  the  rocks ; 
when  he  wakes  up  at  dawn  next  day,  all  he  sees  is  a  slender  rivulet  of 
water,  only  visible  here  and  there  among  the  masses  of  gravel 

But  the  torrents  which  must  be  instanced  as  the  most  striking  types  of 
the  merely  temporary  water-course  are  the  ouadys  in  the  Sahara  and  the 
plateaux  of  Arabia,  and  the  liquid  masses  which  sometimes  roll  down  the 
quebradas  of  Bolivia  and  the  Argentine  pampas.  All  round  the  Red  Sea, 
embracing  an  extent  of  more  than  1550  miles  of  coast-line,  thei'e  does  not 
exist  one  permanent  stream.  All  the  ouadys  which,  during  heavy  rains, 
flow  into  the  sea,  convey  1;o  it  only  the  surplus  of  the  surface-water  which 
the  sand  of  the  desert  was  not  able  to  absorb.  In  a  general  way,  before 
the  complete  disappearance  of  these  streams,  most  of  which  run  over  a 
bed  of  subterranean  rock,  they  ooze  up  imperceptibly  through  the  sand, 
and  show  themselves  in  pools  stagnating  in  the  passes  of  the  defiles.  In- 
stances of  streams  thus  converted  into  a  chain  of  ponds  are  very  numer- 
ous in  deserts  all  over  the  world — in  Arabia  and  Algeria,  in  the  Caspian 
steppes,  and  in  the  North  American  solitudes. 

In  these  regions  the  ground  on  the  plateaux  and  in  the  plains  is  fur- 
rowed with  valleys  exactly  like  those  found  in  tlie  country  that  is  well 
watered  with  rivulets,  streams,  and  rivers.  The  river-system  exists  in 
full  force,  and  for  hundreds  of  miles  the  traveler  may  trace  wide  hollows, 
perfectly  developed,  which  would  contain  rivers  like  the  Danube  or  the 
Rhine,  and  on  either  side  debouch  the  stony  stream-beds  of  the  lateral 
valleys.  Nevertheless,  these  deep  and  winding  depressions,  hollowed  out 
by  the  temporary  waiter-courses,  generally  contain  nothing  but  pebbles 
and  sand ;  water  is  altogether  wanting  except  during  the  season  of  the 
periodical  rains.  One  of  these  waterless  rivers,  the  Roumah,  which  con- 
nects its  bed  with  the  Euphrates,  not  far  from  the  mouths  of  the  Chat-el- 
Arab,  is  not  less  than  750  miles  in  length.  The  only  pennanent  ele- 
ments, so  to  speak,  of  its  vast  drainage  area  are  a  few  springs  and  rivu- 
lets flowing  from  the  mountain  sides  round  the  circumference  of  its 
basin. 

In  the  upper  part  of  their  couree,  these  torrent-waters  assist,  as  we 
have  said,  in  modifying  the  relief  of  the  terrestrial  surface ;  but  these 


288 


THE  EAMTH. 


magnificent  operations  of  erosion,  which  crumble  away  mountains,  or,  at 
least,  by  enlarging  the  clefts,  ultimately  convert  mere  fissures  into  open- 
ings of  such  important  dimensions  both  in  width  and  depth,  are  not  the 
work  of  the  torrents  alone.  The  latter,  in  fact,  are  scarcely  the  chief 
agents  in  the  work ;  they  do  little  else  than  clear  away  the  stones  and 


Fig.  98.  Tbe  Igharghar. 

debris  fallen  from  the  heights  above.  All  the  meteoric  phenomena  of  the 
atmosphere — among  which,  however,  snow  and  rain  may  certainly  be  con- 
sidered as  the  real  orign  of  torrents — contribute  to  the  work  of  destruc- 
tion, and  detach  from  the  mountain-sides  masses  of  debris^  which  accumu- 
late at  the  foot  of  the  rocks  in  more  or  less  inclined  slopes.    The  torrent 


EROSIVE  ACTION  OP  TORRENTS. 


289 


into  which  this  debris  crumbles  down  washes  away  all  the  sand  and  light- 
er matter,  until  the  time  when,  swelled  by  rain  and  melted  snow,  it  rolls 
down  toward  the  valley  the  great  blocks  of  rock  that  have  fallen  into  its 
bed.  It  is  difficult  to  restrain  a  feeling  of  dread  when  we  pass  along  the 
bank  of  a  flooded  torrent  and  hear,  above  all  the  uproar  of  the  water,  the 
dull  thunder  of  the  masses  of  stone  dashing  one  against  the  other  as  they 
are  hurried  along  under  the  rushing  water,  yellow  with  the  earth  which 
it  washes  away. 

Thus,  year  after  year  and  century  after  century,  the  torrent  clears 
away  whole  mountain  sides  which  have  crumbled  down  into  it  rock  by 


KVk:W/.v^ ?\->^=w<fef";>'-  -a^V 


-;^■W^-^^^^«^MHi!W^I!ltv 


Fig.  99.  Valley  of  Cog^ie. 

rock,  and  this  great  work  of  erosion  is  incessantly  going  on.  In  some 
mountain  groups,  where  the  rocks  are  easily  shifted  by  the  action  of  the 
weather,  nothing  is  left  but  a  mere  skeleton  of  those  former  proud  heights 
which  once  towered  up  toward  heaven.  But 
in  the  regions  where  the  mountain  strata 
are  of  a  compact  formation,  and  the  water 
consequently  takes  some  considerable  time 
to  penetrate  them,  all  that  we  notice  in 
tlie  way  of  dilapidation  are  large  holes 
which  the  torrents  have  gradually  hollow- 
ed out  in  the  body  of  the  rock.  Where 
two  mountain  rivulets  form  a  junction,  it  is 
very  seldom  that  the  three  headlands  which 
overlook  the  confluence  do  not  leave  at  their 
base  a  small  triangular  valley,  whence  the  Fig.ioo.  Qnadrangniar  basin  of  erosion ; 

r  ,      ,  T  ■'*^''  Sonklar. 

water  leaps  down  mto  the  lower  gorge.     In 

like  manner,  when  two  streams  proceeding  from  directly  opposite  ravines 

fall  into  the  main  stream  of  the  valley  at  the  same  spot,  the  little  plain 


290  ^^^  EARTH. 

of  erosion  which  is  found  at  theii*  confluence  generally  assumes  a  quad- 
rangular form.  It  must,  however,  be  understood  that  the  dimensions  and 
the  outlines  of  these  basins  must  vary  infinitely  according  to  the  force 
of  the  torrents,  the  hardness  of  the  rocks,  and  the  energy  of  the  agents 
that  attack  them.  Ultimately,  the  surface  of  the  country,  having  been 
carved  out  by  the  water  for  an  unknown  number  of  centuries,  completely 
changes  its  aspect;  the  mountains  and  the  plateaux  ai-e  swept  down  by 
the  rivers,  and  little  else  remains  but  the  isolated  landmarks  of  the  an- 
cient piles. 

There  is  probably  no  country  in  the  world  where  this  devastation  goes 
on  more  rapidly  than  in  the  French  Alps.  The  mountains  of  this  region, 
and  especially  those  which  inclose  the  basins  of  the  Durance  and  its 
tributaries,  are  in  general  composed  of  very  hard  rocks  alternating  with 
other  beds,  which  easily  give  way  under  the  action  of  the  water;  in 
every  place  we  may  notice  immense  cliffs  resting  upon  bases  without  any 
solid  consistence.  The  marls,  the  disintegrated  schists,  and  the  other  fri- 
able matter  are  gradually  washed  away,  and  their  fall  precipitates  that 
of  the  compact  layers  at  the  summit,  which  suddenly  fall  down  or  glide 
slowly  into  the  valleys.*  It  is,  however,  the  improvidence  of  the  inhab- 
itants, and  not  so  much  the  geological  constitution  of  the  soil,  which  is 
the  principal  causg  of  the  devastating  action  of  the  streams.  In  the 
mountains  of  Dauphiny  and  Provence,  the  slopes,  most  of  which  are  now 
so  bare,  were  once  covered  with  trees  and  various  plants  which  kept 
back  the  sui'face-water  resulting  from  the  rain  or  melting  of  the  snow,  by 
absorbing  a  great  part  of  the  falling  moisture,  and  thus  retaining  the 
coating  of  vegetable  earth  over  the  beds  of  crumbling  rock.  During  the 
course  of  centuries,  the  trees  have  been  cut  down  by  greedy  speculators, 
and  by  senseless  farmers  who  wished  to  add  some  little  strips  of  land  to 
the  fields  in  the  valleys  and  to  the  pastures  on  the  summits ;  but  when 
they  destroyed  the  forest  they  also  destroyed  the  very  ground  it  stood  on. 

The  rain  or  snow,  being  now  no  longer  kept  back  upon  the  slopes  by 
the  roots  of  the  trees,  descends  rapidly  into  the  valley,  driving  before  it 
all  the  debris  torn  away  from  the  sides  of  the  mountain.  The  tooth  of 
thte  goat  and  the  sheep  helps  to  lay  bare  the  rootlets  of  the  herbaceous 
plants  and  the  brush-wood ;  bit  by  bit,  the  whole  of  the  thin  coating  of 
vegetable  earth  is  removed,  the  bare  rock  shows  itself,  and  deep  ravines 
are  hollowed  out  in  the  cliffs,  and  are  traversed  in  the  rainy  seasons  by 
furious  torrents  which  once  did  not  exist.  The  water  which  used  slowly 
to  penetrate  the  earth,  conveying  fertilizing  salts  to  the  roots  of  the  trees, 
now  serves  no  other  purpose  than  that  of  devastation.  When  the  forests 
are  gone,  great  furrows  of  erosion  may  be  noticed  opening  out  at  inter- 
vals on  the  slopes ;  these  furrows  often  correspond  to  ravines  situated  on 
the  other  side  of  the  mountain,  and  in  a  comparatively  short  space  of 
time  they  ultimately  sever  the  ridge  of  the  mountain  into  distinct  peaks, 
uniformly  surrounded  by  a  slope  of  rocks  or  fallen  earth :  summits  of  this 
*  Scipion  Gras ;  Rozet ;  De  Ladoucette  ;  De  Bibbe. 


EROSIVE  ACTION  OF  TORRENTS. 


291 


kind  are  being  forme'^  every  year.     In  some  localities  there  is  not  a  sin- 
gle green  bush  over  a  space  of  several  leagues  in  extent ;  the  scanty  gray- 


Fig.  101.  Valle/s  of  Erosion  of  the  Bonrgogne. 
/ 

colored  pasturage  is  scarcely  visible,  here  and  there,  on  the  slopes,  and  ru- 
ined houses  blend  with  the  cinirabling  rocks  that  surround  them.  The 
stream  in  the  valley  is  generally  nothing  but  a  scanty  rill  of  water  wind- 


292  ^^^  EARTH. 

ing  among  the  heaps  of  stones;  but  these  very  heaps  of  shingle  and  rock 
have  been  carried  down  by  the  torrent  itself  in  the  days  of  its  fury.  In 
many  parts  of  its  course,  the  Haute  Durance,  which  is  generally  not  more 
than  30  feet  wide,  seems  lost  in  the  midst  of  an  immense  bed  of  stones,  a 
mile  and  a  quarter  wide  from  bank  to  bank.  The  Mississippi  itself  does 
not  equal  it  in  dimensions. 

The  devastating  action  of  the  streams  in  the  French  Alps  is  a  very  cu- 
rious phenomenon  in  an  historical  point  of  view ;  for  it  explains  why  so 
many  of  the  districts  of  Syria,  Greece,  Asia  Minor,  Africa,  and  Spain  have 
been  forsaken  by  their  inhabitants.  The  men  have  disappeared  along 
with  the  trees ;  the  axe  of  the  woodman  no  less  than  the  sword  of  the 
conqueror  have  put  an  end  to  or  transplanted  entire  populations.  At  the 
present  time,  the  valleys  of  the  Southern  Alps  are  becoming  more  and 
more  deserted,  and  the  precise  date  might  be  approximately  estimated  at 
which  the  Departments  of  the  Upper  and  Lower  Alps  will  no  longer  have 
any  home-born  inhabitants.  During  the  three  centuries  that  have  elapsed 
between  1471  and  1776,  the  vigneries  of  these  mountainous  regions  have 
lost  a  third,  a  half,  or  even  as  much  as  three  quarters  of  their  cultivated 
ground,  and  the  men  have  disappeared  from  the  impoverished  soil  in  the 
same  proportion.  From  1836  to  1866,  the  Upper  and  Lower  Alps  have 
lost  25,090  inhabitants,  or  nearly  a  tenth  of  their  population.  At  the 
present  time,  in  an  area  of  3860  square  miles,  embraced  between  Mont 
Thabor  and  the  Alps  of  Nice,  there  is  not  a  single  group  of  inhabitants 
which  exceed  the  number  of  2000  individuals.  Barcelonnette,  the  most 
considerable  place,  has  more  than  once  been  in  danger  of  being  carried 
away  by  the  stream,  the  bed  of  which  is  higher  than  the  streets  of  the 
town;  the  latter  certainly  would  be  still  less  populous  were  it  not  that 
the  numerous  functionaries  necessary  in  every  sub-prefecture  tend  to  give 
it  an  artificial  life.  Without  the  employes  and  the  custom-house  officers, 
who  almost  consider  themselves  as  exiles,  the  whole  extent  of  a  great 
portion  of  these  mountainous  regions  would  be  nothing  more  than  a 
gloomy  solitude.  It  is  the  mountaineers  themselves  who  have  made  and 
are  seeking  to  extend  this  desert,  which  separates  the  tributary  valleys 
of  the  Rhone  from  the  populous  plains  of  Piedmont.  If  some  modem 
Attila,  traversing  the  Alps,  made  it  his  business  to  desolate  these  valleys 
forever,  the  first  thing  he  should  do  would  be  to  encourage  the  inhabit- 
ants in  their  senseless  work  of  destruction.  Is  it  necessary  that  inan 
must  ultimately  rid  the  mountains  of  his  odious  presence,  so  that  the  latter, 
left  to  the  kind  offices  of  beneficent  nature,  may  again  some  day  recover 
their  forests  of  fir-trees  and  their  thick  carpet  of  flower-studded  turf? 

Although  the  torrents  lower  the  mountains,  on  the  other  hand  they  ele- 
vate the  plains ;  but  their  deposits,  not  being  pulverized  into  clays  and 
sand,  are  often  the  means  of  bringing  another  disaster  on  the  inhabitants, 
who  find  their  fertile  land  covered  beneath  enormous  masses  of  rocks  and 
pebbles.  In  fact,  when  a  stream  empties  itself  into  a  valley  which  has  a 
moderately  inclined  slope,  and  the  former  consequently  experiences  a  sud- 


TALL 


293 


den  check  in  its  progress,  it  deposits  over  a  long  extent  of  descent  all  the 
debris  which  it  conveys  in  its  water  or  rolls  down  before  it.  The  masses 
of  rough  alluvium  accumulate  on  both  sides  of  its  course,  so  as  to  form  a 
rising,  with  regular  slopes  abutting  against  the  escarpments  of  the  mount- 


I'i^.  111.'.  Talus  oi  Debris  in  the  Valley  of  the  Adige. 

ain.  Even  in  places  where  the  stream  once  rushed  down  into  the  valley 
in  rapids  or  cascades,  its  tendency  always  is  to  conceal  gradually  every 
irregularity  in  its  old  bed  under  the  ever-increasing  slope  of  rocks,  peb- 
bles, and  sand.  The  deep  ravine  of  the  upper  valley  is  succeeded  by  a 
long  embankment,  which,  continuing  the  incline,  pushes  out  far  into  the 
principal  valley,  and  forces  the  stream  to  describe  a  considerable  bend 
round  the  base  of  the  cone  of  debris.  Some  of  these  banks  attain  very 
important  dimensions ;  they  accumulate  to  an  enormous  extent  at  the 
outlet  of  each  lateral  ravine  opening  into  the  elevated  valley  of  the  Adige, 
to  the  south  of  the  (Etzthal  group.     One,  that  of  the  Litznerthal,  is  1036 


feet  in  height  at  the  outlet  of  the  ravine,  and  extends  4148  yards  in  length 
as  far  as  the  Adige,  with  a  mean  slope  of  4°  46' ;  the  curve  of  the  river 
which  winds  round  its  base  is  not  less  than  five  miles  in  length. 

When  the  streams  empty  their  waters  into  a  mountain  lake,  and  not 
into  a  valley,  the  debris  which  they  carry  down  accumulates  at  the  upper 
end  of  the  lacustral  basin,  forming  a  slope  much  more  abrupt  than  the 
mass  of  stones  deposited  at  the  entry  of  a  ravine.  In  fact,  at  the  outlet 
of  the  latter  the  water  of  the  torrent  continues  to  flow  over  the  masses 
which  it  has  heaped  up;  fresh  materials  are  continually  being  brought 
down,  some  of  a  small,  others  of  a  large  size,  which  serve  both  to  prolong 
the  slope  and  to  render  it  more  and  more  uniform  with  that  of  the  plain 
below.  In  lakes,  on  the  contrary,  a  separation  immediately  takes  place 
in  the  various  debris  brought  down  by  the  current.  The  blocks  of  stone 
and  pebbles  fall  by  their  own  weight  into  the  depths  of  the  water,  and 
form  a  kind  o{  moraine^  which  incessantly  pushes  on  into  the  quiet  water. 


294 


THE  EARTH. 


Fig.  104.  Ancient  Lakes  and  Defiles  of  Aluta. 


The  lighter  alluvium,  which  is  held  in  suspension  by  the  liquid  mass,  is 
partially  carried  on  by  the  current  toward  the  middle  of  the  lake ;  but 
the  greater  part  of  this  matter  is  soon  dropped  on  each  side  of  the  em- 
bouchure, and  ultimately  extends  in  horizontal  promontories  above  the . 
accumulated  mass  of  heavier  rubbish.     Thus  the  bed  of  the  stream,  with 


Fig.  105.  Lakes  of  Thun  and  Brienz. 


FLUVIATILE  DEPOSITS.  295 

its  Steep  slope  of  stones  in  front,  bordered  by  its  layers  of  lighter  allu- 
vium, incessantly  encroaches  on  the  lake. 

A  large  number  of  lakes  have  thus  been  gradually  filled  up  altogether; 
in  several  high  mountain  valleys,  where  lakes  exist  at  intervals  one  above 
another,  all  the  basins  have  in  turn  been  filled  up.  In  other  places  the 
upper  pools  only  are  choked,  and  the  work  is  going  on  in  one  of  the  low- 
er lakes,  which,  sooner  or  later,  will  ultimately  be  converted  into  a  hoiy- 
zontal  plain.  By  very  carefully  measuring  the  annual  deposits  of  a  tor- 
rent, and  ascertaining,  by  boring,  the  depth  of  the  former  lakes  which 
they  have  filled  up,  the  number  of  centuries  might  be  approximately  esti- 
mated which  this  immense  work  has  taken.  Also,  sounding  the  depths 
of  the  basins  which  are  still  full  of  water  would  show  the  duration  of 
ages  which  will  be  required  to  fill  up  their  abysses.  At  the  foot  of  the 
great  group  of  the  Bernese  Alps,  on  the  isthmus  of  Interlachen,  so  well 
known  to  travelere,  it  would  be  comparatively  easy  to  make  the  experi- 
ments necessary  for  the  solution  of  this  problem,  which  would  also  in- 
form us  approximately  as  to  the  duration  of  the  geological  period  during 
which  the  streams  have  flowed  down  from  the  mighty  group  over  which 
towel's  the  Jungfrau.  For  this  calculation  it  would  be  necessary  to 
measure  the  present  deposits  of  the  furious  Lutschine,  and  to  estimate 
the  enormous  solid  mass  of  the  isthmus  of  Interlachen,  which  has  been 
thrown  down  by  the  stream  as  a  kind  of  dam  between  the  two  lakes  of 
Brienz  and  Thun,  which  once  formed  only  one  lacustrine  basin. 


296  2!a:£^  earth. 


CHAPTER  XLVm. 

EROSION   OF   LACUSTRINE   DIKES. CATARACTS  AND   RAPIDS. 

While  crossing  the  lakes  situated  at  the  bases  of  the  mountains,  the 
watere  of  the  torrent  become  tranquilized,  and  their  course  regulated  ;* 
they  emerge  from  the  basin  in  streams  of  a  less  turbulent  shape,  and, 
flowing  on  to  join  other  water-courses,  descend  with  them  quietly  to  the 
sea. 

But  even  the  outlet-stream  of  the  lake,  although  usually  more  peace- 
able than  the  water-course  above,  accomplishes  its  special  geological  la- 
bor, and  is  also  employed  in  the  task  of  doing  away  with  the  lacustrine 
basin.  The  water,  impelled  by  its  own  weight,  constantly  wears  away 
the  layers  which  form  the  lower  margin  of  the  lake.  The  edge  of  this 
margin  being  gradually  destroyed  by  the  liquid  mass,  sinks  by  slow  de- 
grees, and  the  average  level  of  the  water  in  the  lake  sinks  also  in  the 
same  proportion.     Thus,  at  the  two  extremities  of  the  basin  the  river  is 


Fig.  IOC.  Filling  up  of  a  Lake-basin. 

carrying  on  two  kinds  of  work,  contrary  in  appearance,  but  which  have 
both  an  equivalent  result  in  reducing  the  area  of  the  lake  which  the  river 
crosses.  Up  above,  it  gradually  elevates  its  bed,  and  gains  on  the  lake 
by  filling  it  up  with  alluvium ;  down  below,  it  lowers  the  brink,  and,  by 
this  constantly  increasing  waste-gate,  gradually  drains  out  the  water. 
The  two  stream-beds,  the  upper  and  the  lower,  will  ultimately  meet  in 
the  middle  of  the  lake,  and  the  latter  will  cease  to  exist.  This  is  the 
double  phenomenon  which  has  been  going  on  for  ages  in  the  Lake  of  Ge- 
neva. This  crescent-shaped  sheet  of  water  certainly  once  extended  as 
high  up  the  stream  as  the  place  where  the  town  of  Bex  now  stands,  11^ 
miles  from  the  end  of  the  lake ;  it  also  extended  down  the  stream  in  nar- 
row basins  as  far  as  Ecluse,  9^  miles  from  the  outlet  of  the  Rhone. 

It  must,  however,  be  undei'stood  that  the  outlets  of  lacustrine  reservoirs 
are  not  the  only  places  where  the  rapids  and  cataracts  of  a  river  crumble 
away  the  rocks  so  as  to  lower  the  up-stream  and  elevate  the  down-stream 
beds.  However  hard  may  be  the  strata  which  form  the  bed  of  a  rapid, 
the  eddying  waters  ultimately  penetrate  the  stone,  and  deposit  the  debris 
below  the  gulf  that  the  furious  shock  of  the  torrent  has  hollowed  out  at 
*  Vide  the  chapter  on  "Lakes," 


Fig.  lOT.  Allavial  Deposits  of  the  Rhone  and  the  Drauc>e. 


the  foot  of  the  rocks.  In  like  manner,  cascades  and  cataracts  incessantly 
wear  away  the  ledges  from  which  the  mass  of  their  water  pours  down 
to  the  bottom  of  the  abyss,  carrying  the  great  stones  with  them  in  their 
Tall,  and,  destroying  layer  after  layer,  they  continually  retrograde  toward 
the  source  of  the  river,  and  tend  to  convert  themselves  into  mere  rapids, 
which,  in  some  thousands  of  years  or  perhaps  centuries,  are  destined  to 
assume  a  perfectly  uniform  inclination.  This  is  the  ideal,  so  to  speak,  of 
every  river — to  do  away  with  the  irregularities  of  its  course,  and  to  flow 
down  toward  the  sea,  describing  a  regular  parabolic  curve.  This  ideal, 
however,  is  never  perfectly  attained,  on  account  of  the  diversity  of  rocks 
in  its  course,  the  changes  in  its  bed,  the  disturbances  or  elevations  of  the 
ground,  and  other  circumstances  of  various  kinds  which  may  cause  a  de- 
viation in  its  current.  But  whatever  may  be  the  obstacles  which  oppose 
the  leveling  of  the  declivity,  still  every  I'iver  intersected  by  falls  and  rap- 
ids is  constantly  at  work  in  effecting  the  general  uniformity  of  its  slope. 

In  their  magnificent  beauty,  cataracts  and  rapids  only  yield  the  pre- 
eminence to  hurricanes  and  volcanic  eruptions.  Of  the  former,  there  are 
some  in  Europe  which  are  very  remarkable:  such  as  the  falls  of  the  Rhine 
at  Schaff'hausen  ;  the  four  cataracts  of  the  Gotha-Elf  at  TroUhata  (dwell- 
ing of  sorcerers) ;  the  Hjommel-saska  (the  hare's  leap),  where  the  river 
Lulea  plunges  over  in  a  body  from  a  height  of  264  feet ;  and  the  Riu- 
kan-fos  (roaring  cascade),  which  falls  at  the  outlet  of  the  Norwegian  lake 
Mjosvand  in  a  single  jet  of  885  feet.  The  most  celebrated  water- fall  in 
the  whole  world  is  that  of  Niagara — "  the  falling  sea" — the  constant 
thunder  of  which  may  sometimes  be  heard  12  miles  off".  Above  the  cat- 
aract the  river,  which  discharges  on  the  average  1 300  to  1 400  cubic  yards 
of  water  a  second,  breaks  against  the  shore  of  Goat  Island,  and  divides 
into  two  rapidly  inclined  currents.     Even  at  this  point  the  mass  of  water 


298 


THE  EARTH. 


is  impelled  by  such  velocity  of  move- 
ment that  engineers  have  not  yet 
been  able  to  sound  its  depth,  and 
they  have  similarly  failed  to  do  so 
below  the  cataract.  On  reaching 
the  edge  of  the  cliff,  the  two  halves 
of  the  river — one  655,  and  the  other 
295  yards  wide — take  their  final 
leap,  and  describe  their  vast  para- 
bola, 147  feet  and  160  feet  in  height. 
A  gloomy  passage,  penetrated  by 
furious  gusts  of  wind,  opens  be- 
tween the  wall  of  rock  and  a  sheet 
of  water,  18  to  33  feet  in  thickness, 
which  curves  widely  overhead  like 
an  immense  arch  of  crystal.  Col- 
umns of  iridescent  vapor  spring 
from  the  whirlpool  of  the  roaring 
waters,  and  half  hide  the  two  white 
masses  of  the  cataracts.  At  every 
instant  of  the  day,  following  the 
path  of  the  sun,  the  great  rainbow 
painted  on  the  wavering  and  misty 
spray  shifts  its  position,  and  thus 
modifies  the  aspect  of  the  fall.  The  various  seasons,  each  in  their  turn, 
add  some  feature  of  beauty  to  the  magnificence  of  the  spectacle.  The 
trees  still  left  on  Goat  Island  and  the  cliffs  contrast  with  the  Avhiteuess 
of  the  water — in  summer  by  their  verdure,  in  autumn  by  the  more  varied 
colors  of  their  foliage.  In  winter,  stalactites,  glittering  in  the  sunlight 
like  immense  strings  of  diamonds,  hang  down  from  all  parts  of  the  rock, 
and  serve  ^s  a  frame-work  to  the  two  great  plunging  sheets  of  water.  In 
spring,  when  the  ice  breaks  up,  a  formidable  spectacle  is  presented  by  the 
blocks  of  ice,  like  mountain  fragments,  crowding  together  at  the  edge  of 
the  cataract,  and  crashing  against  one  another  as  they  glide  over  the 
enormous  curve  of  water  which  is  sweeping  them  along. 

Other  great  water-falls  in  different  parts  of  the  earth  afford  similar  phe- 
nomena, and  several  of  their  number  may  even  rival  Niagara  in  their 
beauty.  Among  these  we  may  mention,  in  North  America,  the  magnifi- 
cent falls  of  the  Missouri,  the  Columbia,  and  the  Montmorency.  Of  like 
beauty,  also,  there  is  in  Brazil,  not  far  from  Bahia,  the  wonderful  cataract 
of  San  Francisco,  known  by  the  name  of  Paulo  Affonso,  At  the  foot  of  a 
long  slope  over  which  it  glides  in  rapids,  the  river,  one  of  the  most  con- 
siderable of  the  South  American  continent,  whirls  round  and  round  as  it 
enters  a  kind  of  funnel-shaped  cavity  roughened  with  rocks,  and,  sudden- 
ly contracting  its  width,  dashes  against  three  rocky  masses  reared  up  like 
towers  at  the  edge  of  the  abyss ;  then,  dividing  into  four  vast  columns 


Fi<'.  lOS.  Course  of  the  Niagara. 


FALLS  OF  THE  ZAJIBESL 


299 


of  water,  plunges  down  into  a  gulf  246  feet  in  depth.  The  principal 
column,  being  confined  in  a  perpendicular  passage,  is  scarcely  66  feet  in 
width,  but  it  must  be  of  an  enormous  thickness,  as  it  forms  almost  the 
whole  body  of  the  river.  Half  way  up,  the  channel  which  contains  it 
bends  to  the  left,  and  the  falling  mass,  changing  its  direction,  passes  un- 
der a  vertical  column  of  water,  which  penetrates  through  it  from  one  side 
to  the  other,  and,  breaking  it  up  into  a  chaos  of  surges,  converts  it  into 
a  sea  of  foam.  Sometimes  the  white  misty  vapor  may  be  seen,  and  the 
thunder  of  the  water  may  be  heard,  at  a  distance  of  more  than  fifteen 
miles.* 

Tliis  turbulent  cataract  is  very  different  in  character  from  the  majestic 
falls  of  the  Zambesi,  the  existence  of  which  Livingstone  has  made  known 


ij    ^  i 


Fig.  109.  The  Falls  of  the  Zambesi. 

to  the  world.  Above  the  precipice  the  river  is  calm,  and  flows  over  a 
gently  inclined  bed;  some  islets,  covered  with  cocoa-nut  trees,  are  reflect- 
ed in  the  clear  water.  A  large  island,  called  "  the  Garden,"  on  account 
of  its  rich  vegetation,  divides  the  Zambesi  into  two  branches,  and  the 
general  features  of  the  landscape  are  full  of  grace.  All  on  a  sudden, 
without  the  least  transition,,  the  ground  comes  to  an  end  beneath  the 
water,  and  the  two  liquid  masses,  one  of  which  is  1858  and  the  other  546 
yards  wide,  plunge  down  to  a  depth  of  348  feet  into  the  gaping  fissure  of 
a  vast  mass  of  basalt.  They  then  escape  by  a  narrow  and  winding  chan- 
nel, which  the  river  itself  has  hewn  out  of  the  rock  during  the  lapse  of 
many  centuries.  Ten  columns  of  vapor,  answering  to  ten  great  projec- 
tions on  which  the  body  of  water  dashes  itself  to  pieces,  rise  in  eddies 
*  Ar<f-Lulleinant,  Reise  durch  Nord-Brasilien.  , 


300 


THE  EARTH. 


from  the  foot  of  the  precipice,  and  float,  like  the  smoke  of  a  conflagration, 
far  away  above  the  surface  of  the  river.  They  vary  in  height  according 
to  the  state  of  the  water  and  the  atmosphere ;  but,  generally  speaking, 
they  do  not  rise  less  than  1000  or  1150  feet  above  the  brink  of  the  gulf.* 
On  account  of  these  clouds  of  spray  and  vapor,  the  natives  have  given  to 
the  cataract  of  the  Zambesi  the  name  oi Mosi-oa-Tounya,  or  "Thunder- 
ing Smoke." 

With  regard  to  rapids,  we  find  them  on  most  rivers  at  different  points 


Fig.  110.  Rapids  of  Haypures  on  the  Oriuoco. 


of  their  course ;  either  at  spots  where  cataracts  once  existed,  or  at  the 
mouths  of  streams  which  carry  down  with  them  large  quantities  of  de- 
bris, and  pile  them  up  like  dikes  across  the  current.     The  American  rivers 
,  *  Baines,  Exploration  in  Southwest  Africa. 


FALLS  AND  RAPIDS.  301 

are  the  principal  localities  where  these  rapids  may  be  contemplated  in 
their  full  beauty.  Humboldt  was  the  firet  to  describe  the  raudales  of 
Atures  and  Maypures,  where  the  Orinoco,  changed  into  a  mass  of  foam, 
pours  down  innumerable  cascades  over  a  chaos  of  rocks  and  banks  with 
dark  sides  crowned  with  foliage  and  vei'dure.  Each  mass  of  granite, 
resembling  in  its  shape  some  ruined  tower  or  castle,  is  surmounted  by 
a  group  of  palms  or  densely-foliaged  trees.  Every  stone  below  the  level 
which  the  river  reaches  during  flood-time  is  covered  with  alluvium,  on 
which  the  mimosa,  with  its  delicate  leaves,  grows  abundantly ;  also  ferns 
and  orchids,  with  their  charming  flowers.  They  are  perfect  little  gar- 
dens surrounded  with  foam,  reminding  one  of  the  rocks  covered  with 
flower-studded  turf  which  spring  up  in  the  midst  of  some  of  the  glaciers 
in  Switzerland.  A  cloud  of  vapor  hovers  over  the  river,  and  the  rainbow 
shines  throusrh  the  verdant  hues  of  innumerable  bowers  of  foliage.  This 
is  the  lovely  spectacle  which  the  Orinoco  affords  for  a  distance  of  several 
miles  along  each  of  its  two  rapids.  The  fall  is  not  considerable,  that  of 
the  raudal  of  Maypures  being  scarcely  30  feet ;  but  still  the  slope  is  very 
difficult  to  overcome,  and  in  a  width  of  2841  yards  the  navigable  channel 
is  sometimes  not  more  than  18  feet.* 

About  the  same  time  as  that  when  Humboldt  and  his  friend  Bonpland 
visited  the  rapids  of  Atures  and  Maypures,  Azara  examined  the  great 
salto  of  Maracayu,  where  the  river  Parana,  which,  just  above,  is  4590 
yards  wide,  is  suddenly  contracted  into  a  deep  channel  only  66  yards 
across,  and,  sliding  over  an  inclined  plane  of  60°,  forms  a  fall  of  56  feet  of 
vertical  height.  The  narratives  of  travelers  have  also  made  ns  acquaint- 
ed with  the  rapids  of  the  Madeira,  the  Huallaga,  the  Ucayali,  and  several 
other  rivers,  down  which  the  canoes  of  the  savages  used  to  glance  like 
arrows  in  the  midst  of  the  foam.  In  North  America  the  most  celebrated 
rapids  are  those  which  the  St.  Lawrence  forms  at  its  issue  from  Lake  On- 
tario; but  all-powerful  steam  has  succeeded  in  overcoming  them.  The 
European  rapids  are  not  so  imposing,  on  account  of  the  inferior  quantity 
of  the  river  discharge,  and  also  because  the  general  relief  of  the  continent 
is  much  more  gentle  than  that  of  the  New  World.  We  may,  however, 
mention  the  rapids  of  the  Shannon,  above  Limerick,  the  porogs  of  the 
Dnieper,  and  the  whirlpools  {strudeln)  of  Bingen,  which  were  so  danger- 
ous before  the  rocks  were  blown  up  which  impeded  the  course  of  tlie 
Khine.  Among  the  most  imposing  rapids  in  France,  botli  on  account  of 
their  bulk  and  the  fury  of  their  foaming  water,  and  also  of  the  calm  so- 
lemnity of  the  surrounding  landscape,  are  those  of  the  Gratusse,  formed 
by  the  Dordogne,  some  miles  above  Bergerac. 

In  surveying  both  falls  and  rapids,  there  is  one  point  that  especially 
impresses  tha  mind ;  it  is  that,  in  a  general  way,  immediately  the  water 
has  emerged  from  its  state  of  turbulent  effervescence,  it  assumes  an  un- 
broken surface,  and  spreads  out  into  wide  calm  sheets,  known  in  Spanish 
America  under  the  name  of  remansos.  On  one  side  we  look  down  on  the 
*  Humboldt,  Voyage  aux  Regions  EquinoxialiS. 


302 


THE  EABTH. 


giddy  chaos  of  the  liquid  masses  dashing  against  one  another  as  they 
rush  along ;  on  the  other  we  see  a  pool  of  water  almost  still,  or  at  most 
slowly  rotating.  Here  the  long  gentle  eddies  seem  unable  even  to  move 
the  straws  and  twigs  which  incessantly  float  round  and  round  in  the 
same  circle;  higher  up  the  stream,  the  river  in  its  impetuous  career 
sweeps  away  trunks  of  trees,  tears  up  the  stones  of  its  bed,  and  notches 
out  the  edge  of  the  cliff  over  which  it  falls.  This  contrast  becomes  still 
more  striking  when  we  reflect  that  the  cataract  once  descended  at  the 
very  spot  where  this  tranquil  sheet  of  water  now  lies,  and  that  during  a 
long  course  of  ages  the  fall  has  continually  retrogaded.  The  high  ver- 
tical rocks  which  hem  in  the  two  banks  of  the  river  belong  to  the  same 
geological  formation,  and  the  parallel  lines  of  their  strata  exactly  corre- 


Ommonlara'     ^  J^ 


Fitj.  111.  CiUaract  of  Felou,  tjeuegal. 


spond  on  both  sides.  The  traces  of  the  current  which  has  eaten  away  the 
stone  are  still  visible,  and  the  marks  of  the  work  slowly  accomplished  by 
the  water  can  be  distinctly  traced  out  by  the  eye.  The  immense  cavity 
which  extends  like  a  dark  passage  below  the  fall  has  been  hollowed  out 
by  the  cataract — scooped  out,  so  to  speak,  grain  by  grain. 

The  rate  of  speed  at  which  the  fall  shifts  its  position  might  serve  to 
estimate  approximately  the  age  of  the  river  itself.  If  geologists  had 
studied  this  retrograde  movement  for  a  suflicient  number  of  years,  they 
would  know  the  exact  degree  of  resistance  afforded  by  the  rocks  through- 
out the  whole  length  of  the  cavity ;  they  would  be  able  to  say  with  cer- 
tainty how  many  centuries  the  present  system  has  lasted  with  regard  to 
every  river  which  is  interrupted  in  its  course  by  a  cataract.  But  this 
comparative  study  of  water-falls  has  scarcely  commenced,  except,  perhaps. 


W'EAIimG  AWAY  OF  FALLS.  303 

ill  the  case  of  Niasrara  and  some  other  of  the  sjreat  water-courses  of  North 
America.  According  to  Hall,  Lyell,  and  other  geologists,  the  Falls  of 
Niagara  have  receded  three  miles  and  a  half  in  the  space  of  about  35,000 
years.  The  erosion  of  the  edge  of  the  precipice  is  now  taking  place  at 
the  average -rate  of  12*183  inches  a  year.*    This  is  a  tolerably  rapid 


a.  Niagara  Limestone.  c.  Niagara  Marl. 

b.  Clinton  Group.  d.  Medina  Sandstone. 

Fig.  112.  Profile  of  Cataract  of  Niagara;  after  Marcou. 

movement  of  retrogression,  which,  however,  is  explained  by  the  nature  of 
the  rocks ;  these  latter  are  composed  of  calcareous  strata  resting  on  beds 
of  soft  and  friable  marl.  The  water  penetrates  into  these  layers,  and, 
slowly  undermining  them,  washes  them  away,  thus  throwing  down  the 
upper  strata  in  massive  blocks,  which  are  carried  away  by  the  cataract. 
The  observations  of  M.  Marcou  have  established  the  fact  that  the  volume 
of  water  is  constantly  diminishing  in  the  fall  on  the  American  side,  and 
that,  in  consequence,  the  rocks  there  have  scarcely  been  encroached  upon 
for  some  twenty  year-s.  To  make  up  for  it,  the  great  cataract  is  rapidly 
receding  up  stream,  and  even  now  it  no  longer  assumes  the  graceful  semi- 
circular form  which  obtained  for  it  the  name  of  the  "  Horse-shoe  Fall." 
In  an  interval  of  time  which  may  be  estimated  ^t  eight  or  ten  centuries, 
the  cliff  of  the  cataract  will  probably  be  lowered  as  far  back  as  the  little 
islets  of  the  Three  Sisters ;  the  whole  liquid  mass  will  then  rush  down 
the  current  which  runs  along  the  Canadian  shore,  and  the  branch  on  the 
^Vmerican  side,  no  longer  receiving  any  water,  will  gradually  dry  up ; 
<Toat  Island  will  become  united  to  the  main-land,  and  the  River  Niagara, 
constantly  receding  toward  Lake  Erie,  will  pour  down  the  whole  of  its 
water  in  one  formidable  fall. 

It  may  likewise  be  presumed  that  the  hei>;ht  of  the  cataract  Vill  tend 
to  increase ;  for  the  calcareous  strata  which  gave  way  under  the  weight 
of  the  water  gradually  augment  in  thickness  in  the  up-stream  direction. f 
But  we  are  scarcely  warranted  in  estimating,  even  approximately,  the 
time  wiiich  the  Niagara  will  take  in  receding  to  Lake  Erie ;  for,  as  M. 
Marcou  remarks,  the  prodigious  manufacturing  activity  of  the  Americans 
may  much  modify  matters  in  this  respect.     A  canal,  which  is,  infact,  a 

*  According  to  Lyell.  Mr.  Bakewell  says  that  the  annual  retrogression  of  the  falls  has 
l)een  nearly  a  yard  since  1790. 

t  Marcou,  Bull.  Soc.  Geol.  de  France,  2d  Series,  vol.  xxii. 


30J:  THE  EARTH. 

perfect  river,  already  turas  a  large  number  of  mills  on  the  American  side ; 
and  if  the  river  is  tapped  by  thirty  or  forty  conduits  of  this  importance, 
the  mighty  Niagara  will  become  nothing  but  a  humble  rivulet.  "Arts 
and  manufactures  will  have  disarmed  the  thundering  Jupiter."  But 
Lake  Erie  itself,  which,  according  to  Ellet,  contains  at  present  more  water 
than  the  fall  could  run  off  in  six  or  eight  years,  will  be  perhaps  filled  u]) 
with  alluvium  before  Niagara  has  been  able  to  wear  away  the  lower 
ledge  of  rocks  which  prevents  the  lake  from  rushing  down  bodily  into 
the  basin  of  Ontario. 

That  which  the  future  will  perhaps  accomplish  as  regards  Niagara  has 
already  taken  place  in  the  Mississippi.  Nearly  half  way  between  St. 
Louis  and  Cairo,  the  river  penetrates  a  defile  which  cuts  through  the 
chain  of  the  Ozark  Mountains ;  rocks  300  feet  in  height  rise  between  the 
two  banks,  and  on  their  perpendicular  sides  may  be  clearly  distinguished 
the  lines  of  erosion  which  were  once  traced  out  by  the  current  of  the 
Mississippi.  In  former  days  these  rocks  formed  a  barrier  over  which  fell 
a  cataract  like  that  of  Niagara,  which,  too,  like  the  former  falls,  constant- 
ly wore  away  the  strata  which  served  as  its  bed.  Above  this  barrier  of 
hills  the  water  of  all  the  upper  tributaries  united  in  a  vast  lake,  which 
extended  north  as  far  as  the  mouth  of  the  Wisconsin,  and,  joining  Lake 
31ichigan  on  the  east,  covered  all  the  immense  prairies  of  the  intervenipg 
peninsulas.*  lu  like  manner,  the  Rhine,  the  Danube,  and  a  great  many 
other  rivers,  the  course  of  which  at  the  present  day  is  tolerably  uniform, 
presented  a  succession  of  lacustrine  ponds,  placed  in  gradation  one  above 
another,  and  united  by  cascades.  The  rocky  barriers  situated  between 
the  ponds  have  been  gradually  demolished  and  washed  away  by  the  wa- 
ter ;  some  of  them  have  even  been  pierced  through  at  their  base,  and  this 
is  the  origin  of  the  natural  bridges  which  throw  their  arches  above  a 
great  number  of  streams' and  rivulets.  The  Pont-de-1'Arc,  which  the  wa- 
ter of  the  Ardeche  has  slowly  bored  out  during  tlie  course  of  geological 
ages,  has  a  span  of  not  less  than  177  feet.  The  famous  natural  bridge  of 
Virginia  is  only  111  feet  in  width. 

By  operations  of  this  kind,  rivers  gradually  regulate  their  slope  and 
effect  a  communication  between  plateaux  of  different  height,  which  sink 
in  successive  gradations  from  the  base  of  the  mountains  to  the  sea-coast. 
Whatever  may  be  the  irregularities  of  the  continental  surface,  running 
waters  ciit  out  their  beds  in  the  form  of  inclined  planes,  and  give  them  a 
more  or  less  regular  slope,  which  is  followed  by  merchandise,  travelers, 
and  even  civilization  itself,  in  order  to  penetrate  into  the  separate  basins 
of  the  river-system.  Every  cut  made  by  a  river  across  a  chain  of  hills  or 
the  side  of  a  plateau  may  be  considered  as  a  gate  opened  through  a  wall 
dividing  two  distinct  regions.  Thus,  in  studying  the  monography  of 
each  river,  it  is  necessary  to  study  specially  the  apertures  which  the  wa- 
ter has  made  through  the  barriers  which  once  opposed  its  free  course. 
By  a  succession  of  victories  obtained  over  enormous  masses  of  rock,  the 
*  Humphreys  and  Abbot,  Report  on  the  Mississippi  River. 


THE  "  GREAT  TOWER"  3Q5 

river  has  succeeded  in  emerging  from  the  lacustrine  reservoirs  where  its 
watei-s  once  lay  dead,  and  has  gradually  constituted  itself  as  a  living  in- 
dividuality ever  at  work  shaping  anew  with  its  waves,  its  alluvium,  and 
the  bars  at  its  mouth.  The  Danube  obtained  its  hydrological  impor- 
tance from  the  time  when  its  waters  ceased  to  be  lost  in  the  former  lakes 
which  have  now  become  the  plains  of  Hungary,  Austria,  and  Wallachia. 

Oftentimes,  when  the  river  thus  cuts  away  a  passage  through  a  rocky 
barrier,  it  leaves  standing  erect,  as  an  evidence  of  the  former  state  of 
things,  an  islet  of  hard  stone  which  it  has  failed  in  washing  away.  In 
the  most  picturesque  parts  of  their  course,  almost  all  large  rivers  exhibit 
some  of  these  solid  masses  which  continue  to  resist  the  pressure  of  the 
water  some  centuries  after  the  destruction  of  the  surrounding  strata. 
Thus,  on  the  Danube,  we  find  those  proud  rocks,  with  their  perpendicular 
sides  towering  up,  like  enormous  pillars,  as  high  as  the  level  of  the  rising 
ground  by  the  river-side,  and  crowned  on  their  summits,  some  with  a  feu- 
dal fortress,  some  with  a  hermitage,  and  some  with  nothing  but  a  clump 
of  bushes  or  brush-wood.  Thus,  too,  in  the  Mississippi,  not  far  from  the 
spot  where  the  whole  body  of  its  water  once  poured  over  a  precipice  in  a 
mighty  cataract,  we  notice  the  fine  rock  which,  from  its  form  and  majestic 
aspect,  has  obtained  the  name  of  the  "  Great  Tower."  This  rock  still 
bears,  at  a  height  of  132  feet,  the  cii'cular  line  of  erosion  which  was  once 
traced  out  by  the  current.  But  although  we  still  find  a  pretty  consider- 
able number  of  these  natural  water-girt  "  towers,"  the  greater  part  of 
those  which  once  existed  have  gradually  disappeared  under  the  action  of 
the  elements,  and  their  place  is  now  marked  only  by  hidden  reefs  or  rocks 
on  a  level  with  the  stream. 

XT 


306  ^^^  EARTH. 


CHAPTER  XLIX. 

FORMATION    OF    ISLANDS, EECIPEOCITY   OF   CUEVES. — WINDINGS   AND   CUT- 
TINGS.— SHIFTING   OF  THE    COUESES    OP   AFFLUENTS. 

It  is  therefore  a  fact  that  rivers,  like  all  other  natural  agents,  never 
cease  in  their  work  of  destruction,  but  they  destroy  only  to  reconstruct 
in  another  place.  They  are  continually  eating  away  rocky  islets,  and  em- 
ploying the  debris  in  the  formation  of  islands  of  sand.  Wherever  some 
obstacle  exists  in  mid-current,  such  as  a  bank  of  rock,  the  trunk  of  a  fallen 
tree,  or  some  construction  of  human  industry,  the  water,  arrested  suddenly 
in  its  course,  divides  into  two  flows  as  if  before  the  cut-water  of  a  ship, 
which,  gliding  round  the  opposite  sides  of  the  obstacle,  rush,  one  on  the 
right  and  the  other  on  the  left^  either  against  the  remainder  of  the  water 
flowing  regularly  down  the  current,  or  in  small  streams  against  the  banks 
themselves.  From  this  results  a  double  encounter ;  the  two-curved  flows, 
being  more  or  less  inflected  and  retarded  by  a  thousand  local  circumstan- 
ces, are  thrown  back  toward  the  middle  of  the  river,  where  they  meet, 
each  having  described  its  parabola.  There,  one  portion  of  each  of  these 
flows  continues  to  descend,  describing  a  more  elongated  parabola,  while 
another  portion  flows  into  the  comparatively  tranquil  space  which  lies  be- 
low the  obstacle,  and  gradually  deposits  on  the  bottom  the  sediment  with 
which  it  is  charged.  Thus  is  formed  the  first  islet,  which  is  destined  to 
increase  by  degrees,  fHid  to  serve  as  a  starting-point  for  a  series  of  other 
islands  and  sand-banks  which  make  their  appearance  in  turn  in  the  extent 
of  tranquil  water  embraced  between  the  parabolas  of  the  two  curved 
flows.  The  Germans  give  these  islands  the  name  of  "  Werder"  (from 
werden,^^  to  grow"  [?]),  to  point  out  their  slow  and  gradual  mode  of  for- 
mation. 

In  conformity  to  this  same  law  of  the  seriation  of  islands,  banks  of  al- 
luvium ought  likewise  to  emerge  regularly  at  the  confluence  of  two  riv- 
ers ;  for  there,  too,  the  masses  of  water  come  in  collision,  and, being  mutu- 
ally repelled,  again  approach  one  another  in  elongated  curves.  In  fact, 
the  tongue  of  land  which  separates  the  two  water-courses  is  often  contin- 
ued by  a  series  of  islets  below  the  confluence ;  but  the  force  of  the  current 
being  considerably  increased  by  the  doubling  of  the  liquid  volume,  and  the 
joint  bed  being  always  much  less  in  width  than  the  sum  of  the  two  beds 
together,  the  stream  must  naturally  gain  in  depth  all  that  it  loses  in  sur- 
face. The  water,  being  confined  in  a  narrower  channel,  hollows  out  the 
bed  with  increased  energy,  and  thus  tends  to  prevent  the  formation  of 
sand-banks.*  The  alluvium  is  deposited  in  the  interval  between  the  two 
*  Von  Hoff,  Verdnderungen  der  JErdoberfldche,  vol.  iii. 

C 


FORMATION  OF  ISLANDS. 


307 


currents,  and  helps  to  lengthen,  in  a  down-stream  direction,  the  "  bee"  or 
tongue  of  land  which  separates  the  two  streams. 


Fig.  113.  Series  of  Islands  in  the  Western  Sciieldt. 

These  chains  of  sandy  islets  would  always  be  deposited  with  the  great- 
est regularity  if  the  river  descended  to  the  sea  in  a  straight  line.  It  is 
true  that  every  water-course,  in  obedienfce  to  the  law  of  gravity,  seeks  to 
scoop  out  for  itself  a  rectilinear  channel,  so  as  to  gain  the  ocean  by  the 
most  rapid  incline.  But  the  irregularities  of  its  bottom  and  banks  consid- 
erably modify  the  direction  of  the  river,  and  cause  it  to  describe  a  series 
of  curves  or  windings,  thus  lengthening  the  total  extent  of  its  course. 
Thus  another  law,  that  of  the  reciprocity  of  curves^  is  combined  with  the 
succession  of  islands  in  beautifying  the  sui-face  and  contour  of  a  river,  and 
in  causing  it  to  incessantly  remodel  the  ground  of  the  valley  through  which 
it  flows  by  hollowing  away  the  ground,  sometimes  on  one  side,  and  some- 
times on  the  other. 

Some  lateral  impulse  communicated  to  the  liquid  mass  is  all  that  is  re- 
quired to  throw  the  current  of  the  river  either  to  the  right  or  to  the  left. 
If  the  water  strikes  against  a  wall  of  rock,  or  any  other  obstacle  placed 
across  the  regular  direction  of  the  stream,  the  latter  rebounds  so  as  to  form 
an  angle  of  reflection  equal  to  the  angle  of  incidence,  and,  induced  both  by 
its  impelling  force  and  the  general  slope  of  the  bed,  it  becomes  more  and 
more  intfected,  and  describes  a  parabolic  curve  toward  the  opposite  bank. 
There  its  curcent  is  again  turned  back,  and  again  takes  an  oblique  course 
across  the  bed  of  the  river.  When  the  first  seriation  is  once  brought 
about,  the  current  must  necessarily  form  a  succession  of  windings,  in  con- 
fonnity  with  the  law  of  the  reciprocity  of  curves,  which  is,  in  fact,  nothing 
more  than  the  law  of  the  pendulum.     Each  oscillation  calls  forth  an  equal 


308 


THE  EARTH. 


and  isochronous  oscillation  in  a  contrary  direction ;  each  curve  calls  forth 
another  curve  of  an  equal  radius  and  equal  velocity.  If  the  fluviatile  econ- 
omy was  not  constantly  modified  by  the  varied  composition  of  the  soil  and 


Fig.  114.  Meanderiug  of  the  Meuse,  at  Jj'umay. 

the  immense  diversity  of  the  obstacles  of  every  kind  which  it  meets  with, 
the  river  would  flow  down  toward  the  sea,  always  forming  a  series  of  zig- 
zags as  regular  as  the  oscillations  of  a  pendulum. 


WINDIN08  OF  RIVERS. 


309 


But  the  mass  of  the  current  does  not  confine  itself  to  merely  striking 
against  the  two  banks  in  turn ;  it  also  continually  weal's  them  away,  and 
modifies  their  outline.  When  the  water  dashes  against  the  bank  with  all 
the  impetus  which  is  communicated  to  it  by  the  current  and  the  action  of 
centrifugal  force,  it  tears  away  the  earth,  dissolves  some  of  the  solid  par- 
ticles, washes  away  the  sand,  and  has  a  constant  tendency  to  penetrate 
farther.  Being  then  driven  back  toward  the  opposite  side,  there,  too,  it 
destroys  and  washes  away  the  soil  before  it  is  repelled  afresh  to  continue 
on  each  shore  alternately  its  work  of  destruction.  Thus,  by  a  law  of  equi- 
librium, the  current  undermines  each  bank  in  turn,  while  its  allu^um  is  de- 
posited at  the  points  of  the  two  bends.  In  consequence  of  the  succession 
of  bends  and  points,  the  windings  are  sometimes  almost  perfectly  annu- 
lar. A  boat  leaving  the  upper  bend  describes  a  long  curve  in  following 
the  river,  and  when  it  arrives  at  last  at  the  lower  bend  it  is  sometimes  ac- 
tually in  sight  of  the  starting-point  that  it  quitted  long  before.  In  the 
greater  part  of  its  middle  courae  the  Mississippi  forms  a  series  of  windings 
so  exactly  like  one  another  that  the  Red  Skin  Indians  and  the  earliest  Eu- 
ropean colonists  were  in  the  habit  of  estimating  distances  by  the  number 
of  curves  which  the  river  described.  These  windings,  however,  in  a  cer- 
tain point  of  view,  are  of  the  very  greatest  utility  for  navigation.  Every 
bend  has  the  effect  of  moderating  the  slope,  and,  thus  retarding  the  veloc- 
ity of  the  current,  proportionately  augments  the  mass  and  the  depth  of 
the  water. 


Big.  lis.  Meanderiogq  of  the  Seine. 


By  dint  of  gradually  washing  away  both  the  upper  and  the  lower  bend 
in  a  contrary  direction  to  one  another,  the  river  constantly  tends  to  dimin- 
ish the  isthmus  of  necks  which  still  connects  the  little  peninsula  with  the 
surrounding  plains ;  thus  the  time  will  ultimately  come  when,  the  isthmus 
having  disappeared,  the  two  bends  will  be  united,  and  the  winding  of  the 


310 


THE  EARTH. 


stream  will  be  converted  into  a  perfect  ellipse.  Then,  unless  the  labor  of 
man  oflfers  any  opposition,  the  whole  liquid  mass  will  flow  on  in  a  straight 
line  along  the  rapid  slope  formed  by  the  junction  of  the  two  bends,  while 
the  water  still  remaining  in  the  old  beds  will  become  sluggish  and  dead  on 
account  of  the  slight  slope  which  is  afforded  to  it  by  the  enormous  curve 
of  the  circuit  in  comparison  to  the  newly-formed  passage.  The  rapid  wa- 
ters of  the  upper  bed  striking  against  the  still  water  in  the  former  winding 
are  suddenly  arrested  in  their  course,  or  even  driven  back ;  they  then  de- 
posit the  earthy  debris  that  they  hold  in  suspension,  and  thus  gradually 
form  nattlral  embankments  of  sand  and  mud  between  the  two  old  beds  of 
the  river.  It  is  not  long  before  a  similar  embankment  likewise  separates 
the  two  beds  of  the  lower  bend,  so  that  the  forsaken  winding  is  ultimately 
left  without  any  communication  with  the  new  current  of  the  river;  its 
water  becomes  stagnant,  and  it  is,  in  fact,  converted  into  a  lake.  In  the 
basins  of  the  Mississippi,  the  Amazons,  the  Ganges,  the  Rhone,  and  the  Po, 
there  are  a  considerable  number  of  these  circular  lakes.     We  may  trace 


Fig.  116.  Meandering  at  Luxech. 


MIDDLE  COURSE  OF  THE  MISSISSIPPI 


PL.XV[ 


£i4<il7'Eriura. 


HARPER   Sc  BROTHEB.S.  NEW  YORK. 


,  Abbot. 


WINDINGS  OF  RIVERS. 


311 


out  with  the  eye,  as  it  were,  three  rivers,  one  of  which,  active  and  living, 
flows  without  interruption  from  its  source  to  the  sea,  while  the  two  others 
on  either  side  are  become  "  dead  waters."    The  remains  of  them,  scattered 


Fig.  117.  Old  Channels  of  the  Mississippi. 


all  along  the  existing  river,  still  point  out  the  spots  where  once  extended 
its  ring-like  windings.  In  consequence  of  these  alternate  shiflings  of  po- 
sition, the  valley  is  always  much  wider  than  its  river,  and  along  its  cir- 


312 


THE  EARTH. 


cuitous  path  winds  the  continually  changing  bed  of  the  existing  stream. 
In  some  parts  of  its  course  the  Po  only  takes  about  thirty  years  in  forming 
and  destroying  each  of  its  meanders.* 


Fig.  118.  Old  Meanderings  of  the  Rhine. 


The  perforation  of  these  river  isthmuses  is  not  always  brought  about 
by  the  sole  action  of  nature;  many  channels  uniting  two  river-beds  have 
been  dug  out  by  the  hand  of  man,  and,  thanks  to  the  currents  which  have 
*  Elia  Lombardini,  Dei  Cangiamenti  del  Po. 


CUTTING  OF  CHAJnfELS.  313 

deepened  them,  they  have  ultimately-  replaced  the  former  beds.  Some  en- 
gineere  have  gone  so  far  as  to  propose  to  carry  out  a  systematic  series  of 
•peratious  as  regards  the  whole  line  of  the  Mississippi,  and  thus  to  rectify 
the  bed  of  the  river  from  Cairo  to  New  Orleans.  Since  the  colonization 
of  Louisiana,  the  labor  of  man,  assisting  the  action  of  the  currents,  has  al- 
ready rectified  several  beds ;  in  this  way  have  been  formed  the  "  cuts-olf " 
of  Bunch,  Xeedham,  Shrieve,  Point  Coupee,  and  Fer-i-Cheval.  Above 
these  different  points  the  isthmuses  are  much  more  difficult  to  cut  through, 
on  account  of  the  strata  of  compact  and  hard  clay  which  extend  immedi- 
ately below  the  superficial  bed  of  the  modem  alluvium,  and  are  not  easily 
washed  away  by  the  water.  Thus  it  was  that  in  front  of  Vicksburg  a  por- 
tion of  General  Grant's  army  worked  in  vaia  for  several  months  endeav- 
oring to  cause  the  current  of  the  Mississippi  to  pass  through  a  channel 
cut  across  the  narrow  isthmus  of  the  right  bank. 

Nevertheless,  all  these  "cuts  off"  dug  out  by  the  hand  of  man  can  not 
fail  ultimately  to  become  obliterated ;  for,  in  conformity  with  the  law  of 
the  reciprocity  of  bends,  a  river,  when  deprived  of  its  windings,  is  not  long 
before  it  forms  new  ones.  This  was  the  case  above  Compiegne,  where  it 
was  vainly  attempted  to  straighten  the  course  of  the  Oise.  In  a  very 
short  time  the  river  made  fresh  windings,  the  development  of  which  was 
found  exactly  to  equal  those  which  had  been  done  away  with.  It  was 
managed  better  in  fixing  the  course  of  the  Midouze,  in  the  Landes,  for 
there  the  ingenious  idea  was  adopted — andibllowed  by  success — of  giv- 
ing to  the  river  a  series  of  meanders  of  perfect  regularity.  When  man 
attempts  to  meddle  with  nature,  he  can  only  succeed  in  permanently  mod- 
ifying its  aspect  by  studying  the  constant  laws  of  its  phenomena,  and  by 
making^s  work  conform  to  these. 

The  idea  of  digging  out  and  maintaining  a  straight  channel  between 
two  parabolic  bends  of  the  Mississippi  is  in  no  way  more  absurd  than  the 
idea  of  constructing  piles  perpendicular  to  the  current  of  the  stream,  in 
order  to  limit  the  bed  of  the  river,  and  to  throw  the  waters  into  a  regular 
channel.  By  operations  of  this  kind,  contrary  to  every  principle  of  hy- 
draulics, our  French  engineers  have  entirely  ruined  the  system  of  the 
Loire,  the  Garonne,  and  several  other  water-courses.  The  Loire — a  river 
which  is  the  despair  of  engineers,  and  still  more  of  boatmen — is  distin- 
guished above  all  the  streams  in  France  by  the  inconstancy  of  its  current, 
and  the  continual  shifting  of  its  navigable  channels.  There  is  a  very  great 
difference  between  the  mass  of  water  which  a  river  rolls  down  in  flood- 
time,  and  the  slender  rivulets  which  slowly  make  their  way  through  the 
sand  in  the  dry  season.  Now,  as  a  lateral  shifting  of  the  current  takes 
place  at  the  time  of  every  fluctuation  in  the  level,  the  result  is  that  sever- 
al temporary  channels  are  formed,  and  obliterated  in  turn.  Some  mouil- 
les,  or  comparatively  deep  holes,  are  certainly  to  be  met  with  almost  con- 
stantly at  the  concave  extremity  of  the  bends,  where  the  partial  currents 
unite ;  but  every  where  else  the  bed  rises  more  or  less  over  its  whole  ex- 
tent, so  as  to  form  ridges  {rdcles),  and  navigation  becomes  impossible  dur- 


314 


THE  EARTH. 


Fig.  119.  Channel  of  Vicksburg. 

ing  a  great  part  of  the  year.  This  fatal  interruption  to  commerce,  repre- 
senting an  annual  loss  of  many  thousands  of  pounds,  would  not  take  place 
if  it  was  decided  to  adopt  the  system  of  "  guiding  banks"  proposed  by  M, 
Edmond  Laporte,*  and  subsequently  by  M.  de  V6zian.  Instead  of  recti- 
linear rows  of  piles  constructed  across  the  bed  of  the  river,  embankments 
should  be  raised  formed  with  a  parabolic  curve,  against  which  the  princi- 
pal current  might  strike  at  all  seasons,  so  as  to  describe  unhindered  its 
regular  series  of  serpentine  curves ;  this  is  the  only  plan  for  insuring  the 
greatest  possible  depth  to  the  channel  for  navigation.  The  annexed  plate, 
borrowed  from  M.  de  Vezian's  work,f  points  out  the  position  which  the  em- 
*  Gironde,  September,  1864.  t  Annales  du  G^nie  Civil,  May,  1863. 


NAVIOATION  CHANNELS. 


315 


bankments  ought  to  occupy,  and  the  direction  that  they  would  communi- 
cate to  the  current  of  the  river. 


Fig.  120.  Diagram  to  show  "  Guiding  Banks." 


Even  if  the  mass  of  water  were  to  remain  the  same  from  year  to  year 
and  from  century  to  century,  it  is  certain  that  the  mere  action  of  the  cur- 
rent, striking  each  bank  in  turn,  would  in  the  long  run  be  sufficient  to  alter 
the  curves  of  the  river,  and  gradually  to  remodel  the  ground  in  the  valley. 
But  the  liquid  mass  of  every  stream  is  incessantly  varying  from  the  com- 
mencement of  spring  until  the  end  of  winter.  It  increases  during  the 
rainy  season  and  when  the  snow  melts ;  it  diminishes,  on  the  contrary, 
when  the  supply  from  the  clouds,  the  snow,  and  the  glaciers  is  not  equiv- 
alent to  the  water  which  is  absorbed  by  the  innumerable  rootlets  of  the 
vegetation  by  the  river-side,  and  by  the  continual  evaporation  caused  by 
wind  and  heat.  Under  the  influence  of  these  various  phenomena  which 
either  increase  or  abate,  the  level  of  every  river  constantly  fluctuates  be- 
tween flood  and  low-water.  The  current  of  the  stream  is  consequently 
shifted,  first  to  one  side  and  then  to  the  other,  andJthus  every  day  con- 
tributes in  a  difierent  way  tqg^he  erosion  or  consolidation  of  each  o'f  its 
banks.  The  quantity  discharged  by  the  river  during  flood -times  being 
five,  ten,  fifty,  or  even  a  hundred  times  as  much  as  at  low-water  seasons, 
it  is  hardly  to  be  wondered  at  that  the  erosion  accomplished  by  the  cur- 
rent should  also  vary  in  very  considerable  proportions. 

By  dint  of  manipulating  the  small  particles  which  it  has  itself  been  the 
means  of  conveying  to  the  alluvial  plains,  the  river  ultimately  succeeds  in 
completely  altering  the  direction  of  its  own  tributaries.  The  short  prom- 
ontories which  are  situated  at  the  confluence  of  the  principal  river  and  the 
streams  which  run  into  it  are  constantly  lengthened  in  a  down-stream  di- 
rection by  all  the  sandy  or  muddy  debris  which  is  deposited  by  the  two 
currents.  The  two  masses  of  water,  which  are  ultimately  to  encounter 
one  another,  tend  to  take  a  direction  more  and  more  parallel  on  each  side 
of  this  increasing  promontory,  and,  developing  their  windings  on  both  sides 
of  their  axis  of  descent,  thus  make  their  way  side  by  side  through  the  plains. 
A  magnificent  example  of  this  inflection  of  river-beds  may  be  Noticed  in 
the  valley  of  the  Rhine  between  Basle  and  Mayence.  All  the  affluents 
that  the  Vosges  and  Black  Forest  send  down  to  the  great  river  bend  to 
the  north  as  soon  as  they  have  emerged  from  their  natal  valley,  and  wind 
through  the  plain,  tending  in  the  same  direction  as  the  current  of  the 


316 


THE  EARTH. 


Rhine.  Above  and  below  this  wide  plain  of  alluvium,  in  which  nature 
has  afforded  no  obstacle  to  the  free  passage  of  the  water,  the  lateral  rivers 
do  not  double  round  in  this  way  before  they  join  the  Rhine.     Being  kept 


Fig.  121.  Middle  Course  of  the  Rhine. 


hack  by  the  mountains  or  hills  which  command  them,  they  fall  directly  into 
the  river  nearly  at  a  right  angle  to  it. 


FLUCTUATIONS  IN  RIVER  LEVELS.  317 


CHAPTER  L. 

PERIODICAL  RISING  OF  STREAMS. — "eMBARRAS"  OP  FLOATING  TREES. — ICE- 
FLOODS   IN   THE   NORTHERN    RIVERS. — INUNDATIONS. 

A  LARGE  supply  of  rain-water  being  the  principal  cause  of  the  swelling 
of  rivers,  the  rainy  seasons  must  necessarily  be  the  times  when  floods  are 
generally  produced.  In  tropical  regions,  where  the  zones  of  clouds  and 
showers  shift  regularly  from  north  to  south  and  from  south  to  north  dur- 
ing the  course  of  the  year,  the  fluctuations  in  river-levels  can  be  calcu- 
lated and  predicted  beforehand,  just  as  the  seasons  themselves,-  according 
to  the  passage  of  the  sun  over  the  ecliptic*  When  the  luminary  shines 
above  the  northern  hemisphei'e,  and  dry  seasons  prevail  on  the  north  of 
the  equator,  the  water-courses  in  the  northern  tropical  zone  become  low, 
and  many  are  completely  dried  up.  During  the  winter  season,  on  the 
contrary,  when  the  sun  has  brought  back  to  the  north  the  rain-clouds  and 
tempests,  than  the  rivulets,  streams,  and  rivers  again  swell  and  flow  brim- 
ful of  water.  The  same  phenomena  take  place  in  a  contrary  or3er  in  the 
southern  hemisphere.  Thus  the  level  of  running  waters  on  the  north 
and  on  the  south  of  the  equator  fluctuates  in  turn,  so  as  to  form  a  kind 
of  annual  tide,  which  in  its  regularity  may  be  compared  to  the  daily  tides 
of  the  ocean.  We  must,  however,  add  that  in  all  tropical  regions  the 
periodicity  of  the  annual  floods  is  variously  modified  both  by  the  relief 
of  the  ground  and  also  by  aerial  eddies  and  other  phenomena  which  have 
an  influence  on  the  falls  of  rain. 

Among  all  the  rivers  of  the  intertropical  zone,  the  floods  of  the  Nile 
have  obtained  the  most  world-wide  celebrity.  Herodotus  and  other  his- 
torians of  Greek  antiquity  have  told,  with  a  sort  of  religious  astonish- 
ment, of  this  periodical  swelling  of  the  sacred  river  which  conveys  to 
Lower  Egypt  the  soil  which  nourishes  it.  To  the  agriculturists  by  the 
river-side  this  beneficent  flood  seemed  like  a  miracle,  and  their  priests 
never  failed  to  take  advantage  of  it,  so  as  to  increase  their  power  among 
the  people.  So  long  as  the  valleys  of  the  Upper  Nile  and  its  tributaries 
were  unknown,  it  was  really  difticult,  when  surveying  the  annual  inunda- 
tions of  the  river,  not  to  consider  it  as  a  prodigy.  The  course  of  the 
Lower  Nile  is  not  fed  by  a  single  tributary;  it  traverses  an  arid  country 
rarely  watered  by  the  rain  of  heaven  ;  a  burning  sun  evaporates  its  wa- 
ter, and  yet,  all  of  a  sudden,  about  the  beginning  of  July,  the  river-level 
rises,  without  any  apparent  cause,  in  its  wide  isle-studded  bed.  The  wa- 
ter rises,  and  goes  on  rising,  and  from  August  to  October  it  covers  the 
sand-banks,  flows  over  its  brink,  and,  inundating  the  banks,  pours  itself 
*  Vide  the  chapter  on  "Clouds  and  Rain." 


318 


THE  EARTH. 


out  in  strata  no  less  regular  than  the  annual  rings  in  the  trunks  of  trees. 
At  the  very  highest  flood  the  river  often  contains  a  mass  of  water  twenty 
times*  as  great  as  that  which  it  conveys  to  the  sea  when  at  its  very  low- 
est, and  yet  perhaps  the  Egyptian  sky  has  not  for  several  months  yield- 
ed a  single  drop  of  rain.  This  prodigy,  incomprehensible  enough  to  our 
ancestors,  may  nowadays  be  easily  explained.  The  enormous  mass  of 
water,  which  serves  to  irrigate  the  cultivated  districts  of  the  delta,  pro- 
ceeds from  the  snow  and  rain  which  the  clouds  so  abundantly  shed  on 
the  mountains  of  Ethiopia  and  on  the  other  countries  of  equatorial  Africa. 
There  are  many  water-courses  in  the  intertropical  zone  which  afford 
the  phenomenon  of  periodical  floods  with  as  much  regularity  as  those  of 
the  Nile ;  but  there  are  none  which  are  more  curious  in  this  respect  than 
the  great  river  of  the  Amazon  basin.  This  "  Father  of  Waters  "  flows 
nearly  under  the  equator,  and  receives  simultaneously  the  affluents  of 
two  hemispheres.  Owing  to  this  arrangement  of  its  river  system,  the 
floods  of  the  northern  rivers  take  place  in  summer  and  autumn,  while 
the  southern  tributaries  overflow  during  the  winter.  The  principal  river 
and  the  Madeira  are  mostly  swelled  by  the  equinoctial  rains,  and  their 
floods  take  place  in  spring  and  summer.  An  actual  system  of  compen- 
sation is  thus  established  in  the  lower  bed  of  the  Amazon  between  the 
tributaries  flowing  in  on  the  right  bank  and  those  on  th»  left.  When 
the  Past^za,  the  Japura,  and  the  Rio  Negro  are  at  low  water,  the  Ucay- 
ali,  the  Madeira,  and  the  Tapajoz  are  running  brimful;  when  the  latter 
begin  to  get  low,  the  northern  affluents  increase  their  mass  of  water. 


Tap^oz. 


Madeira. 
Japura. 
Rio  Negro. 
Amazon. 
Rio  Branco. 


Jan.     Feb.    March.    April.    May.     June.    July.    Aug. 

Sept 

Oct.     Nov.    Dec 

/O^i^-. 

/     /             """'^X     .. 

"^x 

'^V.                     /                  /                                                            >V^                ~      ' "-^ 

•».^ 

^V     /            /                                                  /^-      X^           ^-'^ 

X. 

\     / 

^sif      /                         ^y^  /        ^y 

\-\ 

x^     ^\^                          /       •■■'          ' '    ^^ 

K 

X^                                   ''■■.,yy 

/         -'''    ^^\                   /         '            '■'             v\ 

vJV                         \\ 

■r                         y  ■■■'   ■'■'"'''            ''\. 

'■"Ov       ]  \. 

yy                       /^^yCy''                    \\ 

"wC        \ 

/' X                          .y^  -■*'  '^"^^                         ^ 

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1 

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X                         "v           >* 

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y/                               '-'''               J> 

'*■■—.   •■     """£■' "                                                   ^•^^"^"'^'--^ 

\.^^^^ 

'.rr:---=-^^^~^ 

'~-' 

Fig.  122.  Compensation  of  Floods  in  the  Basin  of  the  Amazon. 

Beyond  the  tropical  zone,  rivers  must  necessarily  manifest  less  regu- 
larity in  their  annual  floods,  the  rains  themselves  being  more  irregularly 
distributed  among  the  various  seasons.  Nevertheless,  an  unquestionable 
system  of  order  never  fails  to  show  itself  each  year  in  the  fall  of  atmos- 
pheric moisture,  and  this  system  is  again  met  with  in  the  corresponding 
fluctuation  of  the  river-levels.  This  is  a  fact  which  may  be  proved  by 
the  study  of  various  water-courses.  In  regions  like  the  north  of  France, 
which  are  favored  with  rains  in  winter,  spring,  and  summer,  the  floods 
*  Elia  Lombardini,  Essai  sur  VHydrologie  du  Nil. 


PERIODICAL  FLOODS.  319 

generally  take  place  between  the  15th  of  October  and  the  15th  of  May, 
and  it  is  only  due  to  the  rapid  evaporation  which  takes  effect  during  the 
hot  weather  that  summer  floods  are  so  very  rare.*  In  the  Mediterranean 
districts,  where  autumn  rains  predominate,  the  water  -  courses  begin  to 
swell  toward  the  end  of  the  year.  In  those  river-basins  which,  from  the 
vastness  of  their  area,  extend  into  several  meteorological  regions,  the 
fluctuations  of  level,  which  succeed  one  another  with  more  or  less  regu- 
larity in  each  of  the  different  affluents,  are  combined  so  as  to  form  a 
fresh  series  of  floods  as  x'egards  the  principal  artery,  and  the  general 
course  of  these  floods  may  be  easily  foreseen.  The  most  striking  exam- 
ple which  can  be  mentioned  is  that  of  the  Mississippi,  a  river  which  unites 
in  its  vast  bed  the  water  coming  from  the  great  western  deserts  and  the 
streams  which  flow  down  the  pleasant  valleys  of  the  AUeghanies.  At 
New  Orleans  the  river  commences  to  rise  about  the  1st  of  December, 
and  its  mass  of  water  increases  until  about  the  middle  of  January,  which 
is  the  time  of  the  first  flood.  Then  the  level  slowly  sinks,  and  afterward 
w-emains  nearly  stationary  during  the  months  of  February  and  March.  In 
*April  and  May  the  river  swells  afresh,  and  in  the  course  of  the  month  of 
June  it  forms  the  great  flood  so  dreaded  by  the  planters.  Immediately 
after  it  sinks  rapidly  until  the  end  of  September,  and  its  lowest  level 
coincides  very  generally  with  the  commencement  of  November. 

Several  water-courses  in  the  temperate  zone  exhibit,  in  the  fluctuations 
of  their  level,  a  phenomenon  of  compensation  similar  to  that  of  the  Ama- 
zon. These  are  rivers  which  are  replenished  simultaneously  by  streams 
fed  by  rain-water,  and  also  by  torrents  increased  by  the  melting  of  snow 
and  glaciers.  The  variations  of  lowland  streams  being,  as  regards  the 
seasons,  precisely  contrary  to  the  variations  to  which  mountain  tributa- 
ries are  subject,  the  level  of  the  main  river  remains  at  a  nearly  regular 
height.  The  rain  -  water  tributaries  diminish  in  bulk  at  the  very  time 
when  the  affluents,  which  have  come  down  from  the  glaciers,  are  increas- 
ing— that  is  to  say,  in  summer ;  in  winter  and  spring,  on  the  contrary, 
the  glaciers  supply  very  little  water,  while  the  plains  are  inundated  with 
rain,  and  their  streams  are  filled  to  the  brink.  Thus  the  abundance  of 
one  affluent  balances  the  poverty  of  another.  As  an  instance  of  this,  the 
Rhone  and  the  Saone  have  often  been  brought  forward.  During  the 
heat  of  summer  the  latter  brings  down  only  one  fifth  of  its  winter  dis- 
charge. On  the  other  hand,  the  Upper  Rhone  rises  much  higher  during 
the  same  season;  but  below  its  junction  with  the  Saone  the  average 
heiglit  of  its  water  is  nearly  the  same  during  every  season  of  the  year. 
A  compensation  of  a  similar  kind  likewise  takes  place  between  streams 
of  surface-water  and  those  which  are  fed  by  springs.  The  rivulets  which 
traverse  the  subterranean  passages  of  rocks  can  not  descend  into  the 
plain  so  rapidly  as  the  water-courses  which  flow  on  the  surface  of  the 
ground. 

The  grandeur  of  the  geological  operations  accomplished  by  flood-wa- 

•  Belgrand. 


320  T^^  EARTH. 

ters  are  best  to  be  appreciated  on  the  banks  of  rivers  which  have  been 
placed  by  the  labor  of  man  in  a  state  of  defense  against  the  watery  ene- 
my. When  the  River  Amazon  overflows,  it  forms  in  some  places,  with 
the  mai-shes  on  its  banks,  a  perfect  sea  of  100  or  even  200  miles  in  width. 
The  animals  seek  a  refuge  in  the  tree-tops,  and  the  Indians  who  live  by 
the  sides  of  the  river  make  a  kind  of  encampment  on  rafts.  About  the 
8th  of  July,  when  the  river  begins  to  sink,  the  water,  returning  to  its 
original  bed,  undermines  the  thoroughly  soaked  banks  and  slowly  washes 
them  away.  A  sudden  fall  then  takes  place,  and  masses  of  earth,  amount- 
ing to  hundreds  or  thousands  of  cubic  yards  in  bulk,  sink  down  into  the 
water,  carrying  with  them  the  trees  and  animals  existing  upon  them. 
The  very  islands  are  exposed  to  sudden  destruction :  when  the  entangled 
masses  of  fallen  trees,  which  serve  as  a  breakwater  to  them,  give  way  be- 
fore the  violence  of  the  current,  a  few  hours,  or  even  a  few  minutes,  are 
quite  sufficient  for  their  disappearance ;  they  are  literally  washed  away 
by  the  flood.  They  may  be  observed  visibly  melting  away ;  and  the  In- 
dians, who  are  quietly  at  work  upon  them  collecting  turtle-eggs  or  dry^| 
ing  the  produce  of  their  fisheries,  are  suddenly  compelled  to  fly  for  their^ 
lives.  Then  it  is  that  the  current  of  the  stream  is  encumbered  with  long 
floating  piles  of  entangled  trees,  which  hitch  together  only  to  break  away 
again,  and,  accumulating  round  some  headland,  are  heaped  up  one  above 
another  all  along  the  banks.  All  round  these  immense  trains  of  trees, 
which  roll  and  plunge  heavily  under  the  impetus  of  the  current  like 
great  marine  monsters  or  drifting  wrecks,  great  masses  of  the  plant  Cari- 
na rana  float  on  the  surface  of  the  water,  giving  to  some  parts  of  it  a 
resemblance  to  broad  meadows.*  We  may  thus  readily  comprehend  the 
almost  religious  awe  which  has  been  experienced  by  travelers  who  have 
made  their  way  up  the  river  of  the  Amazons,  and  viewing  these  whirl- 
pools yellow  with  sand,  have  been  eye-witnesses  of  their  destructive 
operations  in  tearing  away  the  river-banks,  throwing  down  trees,  wash- 
ing away  islands  in  one  place  to  form  them  again  in  another,  and  drifting 
down  the  current  long  trains  of  trunks  and  branches.  "  The  great  river 
was  terrible  to  look  on,"  says  Herndon,  the  American  traveler,  "  as  it 
rolled  through  the  solitudes  with  a  solemn  and  majestic  air.  Its  waters 
seemed  to  wear  a  wrathful,  malevolent,  and  pitiless  aspect.  The  entire 
landscape  had  the  effect  of  stirring  up  in  the  mind  a  feeling  of  horror  and 
dread  similar  to  that  produced  by  the  imposing  solemnities  of  a  funeral 
at  sea,  by  the  minute-gun  firing  at  intervals,  the  howling  of  the  tempest, 
and  the  wild  uproar  of  the  waves,  when  the  crew  assemble  on  the  deck 
to  bury  their  dead  in  the  bosom  of  a  troubled  sea." 

The  Mississippi  presents  a  remarkable  instance  of  a  great  water-course  . 
which  man  has  recently  annexed  to  his  domain,  and  has  succeeded  in 
modifying  considerably,  as  regards  its  geological  action,  during  the  course 
of  a  few  years.  In  1782,  and  even  at  the  time  of  the  great  inundation  of 
1828,  the  whole  of  the  region  embraced  between  the  left  bank  of  the  Mis- 
*  Ave  Lallemant,  Reise  in  Nord-Brasilien. 


ICE  FLOODS.  321 

sissippi  and  the  couree  of  the  Yazoo — that  is,  an  area  of  more  than  30 
miles  in  width  on  the  average — was  completely  covered  with  water,  as  is 
proved  by  the  bones  of  wild  animals  which  have  subsequently  been  found 
on  the  artificial  mounds  raised  by  the  red-skin  Indians.  At  the  present 
day  the  river  is  confined  on  both  sides  by  lateral  embankments,  and  no 
longer  floods  the  whole  basin  of  the  Yazoo.  Now  it  only  tears  away 
narrow  strips  of  the  vast  forests  by  the  river-side;  and  even  in  the  very 
highest  floods,  the  masses  of  trees  which  drift  down  the  current  do  not 
form,  as  before,  long  floating  trains. 

Even  at  the  beginning  of  the  present  century,  these  floating  trains,  or 
emharras^  rendered  the  navigation  almost  impossible  in  some  reaches  of 
the  Mississippi  and  its  tributaries.  A  great  portion  of  the  courses  of  the 
Atchafalaya  and  the  Ouachita  were  completely  choked  up  by  heaps  of 
trees.  In  many  places  a  person  might  cross  them  without  any  idea  that 
he  was  going  over  a  river.  Bushes  and  even  large  trees  grew  upon  some 
of  these  floating  masses.*  One  of  these  entanglements  of  drift-wood, 
known  by  the  Americans  under  the  name  of  the  "  Great  Raft,"  always  ob- 
structs the  bed  of  the  Red  River.  This  immense  agglomeration  of  trees, 
under  which  the  water  disappears  in  a  mass  as  if  under  a  movable  arch, 
gradually  gets  higher  up  the  course  of  the  river  as  the  trees  at  the  lower 
end  break  away,  and  the  annual  floods  bring  down  fresh  drift-wood  to 
the  upper  extremity.  The  obstruction  was  probably  first  formed  at  the 
confluence  of  the  Red  River  and  the  Mississippi,  and  has  since  gradually 
advanced  391  miles  from  the  mouth,  gaining  a  mile  or  two  every  year. 
In  1833  the  Federal  Government  undertook  some  important  operations 
for  the  removal  of  the  obstruction,  which  had  then  attained  a  length  of 
124  milea;  but  while  a  flotilla  of  boats  was  occupied  in  pulling  out  the 
trees  which  formed  the  lower  extremity  of  the  "  raft,"  the  upper  end  was 
constantly  increasing  by  means  of  the  fresh  drift.  In  1855,  after  twenty- 
two  years  devoted  to  this  "  labor  of  Sisyphus,"  the  question  was  raised 
whether  it  was  not  better  worth  while  to  abandon  this  ungrateful  labor, 
and  to  apply  the  funds  at  disposal  to  the  improvement  of  the  bayoxis, 
or  lateral  channels.  "The  Great  Raft,"  being  thus  abandoned  in  the 
marshes,  which  formed  the  old  bed  of  the  river,  will  be  gradually  con- 
verted into  a  great  peat-bed,  destined  perhaps  to  become  coal  at  some 
future  geological  period,  unless  human  ingenuity  should  otherwise  dis- 
pose of  it. 

In  cold  countries,  such  as  British  America,  Russia,  or  Siberia,  the  wa- 
ter-courses carry  down  to  the  sea  a  far  less  quantity  of  vegetable  debris 
than  the  rivers  in  tropical  countries ;  but,  to  make  up  for  it,  they  are 
loaded  with  enormous  blocks  of  ice  at  the  time  of  ]thaw,  a  period  which 
often  coincides  with  the  highest  floods.  It  is  a  wonderful  sight,  especial- 
ly in  rivers  adorned  with  cataracts  like  the  Niagara,  when  the  rocks  of 
ice,  dashing  against  one  another,  and  breaking  up  in  the  midst  of  the 
watery  columns,  give  one  the  idea  of  a  cataclysm,  in  which  lakes  and 
•  Lyell,  Second  Visit  to  the  United  States. 

X 


322  ^-^-^  EARTH. 

continent  were  all  being  simultaneously  swallowed  up  in  the  abyss.  The 
icy  sheet  which  extends  over  the  surface  is  shattered  with  a  sharp,  grind- 
ing noise,  and  the  broken  fragments  are  caught  by  the  current,  and 
dashed  violently  against  each  other ;  their  sharp  angles  are  broken  off  in 
the  collisions,  and  they  are  whirled  round  and  round  in  long  eddies.  In 
the  curves  of  the  headlands,  at  the  points  of  the  islands  and  sand-banks, 
and  also  in  those  portions  of  the  river  where  the  icy  barrier  still  remains 
firm,  the  broken  masses  gradually  accumulate,  and,  mounting  up  one 
upon  another,  owing  to  the  force  of  their  impetus,  butt  against  the  banks 
like  battering-rams,  and  thus  often  clear  away  an  outlet  into  the  plains 
for  the  flood-water.  Sometimes  they  rear  themselves  up  like  dams,  and 
drive  back  the  body  of  the  river  up-stream  again.  For  this  reason,  dikes, 
embankments,  and  other  hydraulic  ramparts,  built  along  the  course  of  a 
river  subject  to  these  anntial  breakings-up  of  the  ice,  must  be  construct- 
ed with  the  utmost  solidity.  Among  other  constructions  of  this  kind, 
we  may  mention  the  enormous  buttresses  with  which  the  piles  are  fur- 
nished to  support  the  bridge  of  Montreal  on  the  St.  Lawrence,  and  the 
defensive  ice-breakers  built  in  the  Vistula  on  the  up-stream  side  of  each 
pier  of  the  bridge  of  Dirschau.  At  St.  Petersburg  the  granite  quays 
and  the  edifices  they  protect  would  be  all  carried  away  by  the  ice-flood, 
if  at  the  same  time  violent  tempests  from  the  west  were  to  drive  the 
waves  of  the  gulf  into  the  mouth  of  the  Neva. 

In  temperate  Europe  the  breaking  up  of  the  river-ice  is  attended  by 
little  or  no  danger ;  but  the  mere  inundations  are  very  much  dreaded  on 
account  of  the  towns,  villages,  and  richly-cultivated  districts  with  which 
the  banks  are  covered.  The  inhabitants  on  the  edges  of  the  Loire  still 
recall  to  mind  with  horror  the  disasters  which  have  been  caused  by  the 
great  though  exceptional  floods  which  in  one  year  only  (1856)  carried 
away  roads  and  defensive  embankments,  causing  damage  to  a  most  enor- 
mous amount.  In  the  same  year  the  calamity  was  but  little  less  disas- 
trous in  the  valley  of  the  Rhone,  which  was  covered  in  some  places,  es- 
pecially the  Camargue,  by  an  inundation  almost  like  one  of  the  floods  of 
the  Amazon.  The  inhabitants  of  the  banks  of  the  rivers  are  now  worse 
off  in  this  respect  than  their  ancestors.  The  extraordinary  rains  caused 
by  atmospheric  changes  are  not  all  they  have  to  dread.  They  have  now  to 
look  for  greater  irregularity  in  the  action  of  the  streams  and  still  more  sud- 
den inundations,  in  consequence  of  so  many  of  the  marshes  and  pools  being 
drained  dry,  and  the  mountain  slopes  being  cleared  of  wood  by  the  axe  of 
the  woodman,  or  laid  bare  by  the  feeding  of  the  goats.  They  also  have  to 
fear  the  immediate  effects  of  the  drainage  channels  which  pour  down  the 
rain-water  so  rapidly  into  the  streams.  Lastly,  the  surface-water  is  every 
year  precipitated  into  the  plains  more  and^iore  suddenly  on  account  of 
the  increasing  number  of  ditches,  which  are  carefully  kept  up  along  the 
roads  and  paths,  into  which  the  boundary  trenches  of  the  various  proper- 
ties all  empty.*  On  the  other  hand,  the  extension  of  cultivation  on  the 
*  Becquerel,  Comptes  Rendtts  de  VAcadevde  des  Sciences,  November,  1866. 


INUNDATIONS. 


Fig.  123.  Liiuiis  of  the  Inondation  of  the  Khoue  in  1840. 

edge  of  a  river,  without  the  application  of  drainage,  enables  the  earth  to 
absorb  the  water  to  a  lower  depth  in  the  soil,  and  thus  diminishes  the 
height  of  the  floods.  This  fact  is  proved  by  the  example  of  the  Lake  of 
Aragua,  in  Venezuela.  At  the  commencement  of  the  century,  when  the 
greater  part  of  the  neighboring  plains  were  under  cultivation,  the  level 
of  its  water  was  comparatively  low ;  but  during  the  War  of  Independence 
it  gradually  rose,  owing  to  the  devastation  of  the  country  by  the  con- 
tending armies,  and  the  consequent  return  of  the  plains  to  their  ori^^inal 
condition  of  virgin  forest.  Latterly,  fresh  clearings  have  for  the  second 
time  sunk  the  water  of  the  lake. 

Under  the  action  of  all  the  causes  which  so  variously  influence  the  flu- 
viatile  economy,  some  rivers,  such  as  the  Oder,  since  1778,  and  the  Elbe, 
since  1828,  have  diminished  in  volume,  although  it  is  certain,  from  the 
meteorological  registers,  that  the  amount  of  rain  falling  into  their  basins 
has  not  lessened.  Other  rivers,  as  the  Rhone  and  the  Loire,  do  not  ap- 
pear to  have  at  all  decreased  in  the  quantity  of  their  water ;  but,  on  the 
other  hand,  their  inundations  are  much  more  dangerous  than  formerly. 
The  Seine,  which,  according  to  the  testimony  of  the  Emperor  Julian, 
poured  through  Paris,  some  fifteen  hundred  years  ago,  nearly  the  same 
quantity  of  water  in  every  season  of  the  year,  shows,  at  the  present  time, 
a  difference  of  about  33  feet  between  the  high  and  low  water  levels. 
Some  rivers,  indeed,  such  as  the  Garonne,  appear  to  have  been  more  for- 
midable in  days  gone  by  than  they  now  are.  The  highest  inundation  of 
the  Garonne  which  is  on  record  is  that  of  April,  1770.  At  Castets,  the 
point  at  which  the  tide  stops,  the  flood-level  attained  a  height  of  42^  feet 
above  the  low-water  mark.  This  is  6^  feet  more  than  in  the  largest  floods 
of  the  present  century.* 

*  Raulin,  Giographie  Girondine. 


324  '^^^  EARTH. 

However  this  may  be,  some  of  these  inundations  assume  such  propor- 
tions that  they  become  perfect  cataclysms  for  all  the  river-side  districts. 
The  example  of  three  little  streams,  the  Doux,  the  Erieux,  and  the  Ar- 
d^che,  all  three  confined  to  the  limits  of  a  single  department,  may  give 
an  idea  of  the  rapid  swellings  of  these  high  floods.  On  the  10th  of 
September,  1857,  the  three  water-courses,  which  usually  flow  peaceably 
enough  over  their  rocky  and  pebbly  beds,  poured  down  into  the  Rhone 
a  combined  mass  of  more  than  18,000  cubic  yards  of  water,  instead  of 
the  20  to  25  yards  which  was  their  ordinary  discharge  in  the  same  time. 
This  flood  was  equivalent  to  the  body  of  water  which  the  Euphrates 
and  Ganges  together  pour  into  the  sea.  Spreading  over  their  respect- 
ive valleys  to  a  height  of  50  to  60  feet  above  their  low-water  mark, 
the  flooded  rivers  overthrew  the  houses,  washed  away  the  cultivated 
ground,  and  uprooted  the  trees.  So  many  thousand  trunks  of  trees  were 
carried  away  in  one  day  that,  below  the  Erieux  and  the  Doux,  the  whole 
surface  of  the  Rhone  seemed  nothing  but  a  train  of  drift-wood,  over 
which,  as  it  appeared,  a  bold  man  might  well  have  ventured  to  cross  the 
river.  Still,  even  these  inundations  have  been  exceeded,  for,  on  the  9th 
of  October,  1837,  the  Ardeche  rose,  at  the  bridge  of  Gournier,  to  a  height 
of  70  feet  above  low-water  mark,  at  least  10  feet  higher  than  in  1857.* 
Above  the  Iron  Gates  some  of  the  floods  of  the  Danube  have  caused  the 
river  to  swell  to  a  height  of  more  than  60  feet  above  low-water  mark. 

It  is  a  fortunate  thing  that,  in  most  river-basins,  it  is  very  seldom  the 
case  that  the  floods  of  the  various  affluents  exactly  coincide,  and  that  all 
the  tributaries  are  seen  to  swell  at  the  same  time.  In  fact,  whenever  a 
rain-cloud  pafises  through  a  valley,  it  discharges  its  moisture  sometimes  on 
one  side  and  sometimes  on  the  other,  and  the  various  water-courses  which 
it  swells  overflow  in  turn  after  the  rain-cloud  has  passed  over.  Thus,  in 
the  valley  of  the  Rhone,  when  the  damp  winds  encounter  the  Cevennes, 
the  slopes  of  the  Alps  which  are  turned  toward  the  river  are  sheltered 
from  the  storm,  and  it  is  only  gradually  that  the  series  of  showers  makes 
its  way  from  the  Cevennes  toward  the  mountains  of  Annonay.  If  all  the 
tributaries  of  the  Rhone  were  to  swell  at  one  time,  it  would  roll  down  a 
most  formidabe  mass  of  water,  amounting  to  more  than  130,000  cubic 
yards  a  second.  It  would  be  another  Amazon.  Even  when  the  Rhone 
discharges  into  the  sea  only  16,000  to  20,000  yards  a  second,  the  havoc 
which  it  makes  upon  its  banks  is  most  frightful. 

*  Marchegay,  Annates  des  Fonts  et  Chaussees,  vol.  i.,  p.  8C1. 


j}£EANS  OF  PREVENTING  FLOODS.  325 


CHAPTER  LL 

MEANS  OF  PREVENTING  FLOODS. — NATURAL  AND  ABTIPICIAL  RESERVOIRS. — 
IRRIGATION   CHANNELS. — EMBANKMENTS,  AND   CRACKS   IN  THEM. 

It  is  evident  that  it  would  not  do  for  man  to  remain  constantly  under 
the  apprehension  of  these  inundations,  and  that  it  was  necessary  to  find 
some  means  of  preventing  them.  For  hundreds  and  thousands  of  years, 
and  especially  during  this  century  of  industrial  activity,  plenty  of  plans 
of  protection  against  river-floods  have  been  both  projected  and  put  into 
execution ;  but  too  often  these  works  have  remained  useless,  or  have  even 
produced  entirely  contrary  effects  to  those  which  were  expected  by  the 
engineers  and  the  inhabitants.  The  fact  is,  that  in  going  to  work  they 
did  not  always  pay  sufficient  attention  to  the  laws  of  hydrology.  If  man 
wishes  to  become  master  of  the  forces  of  nature,  and  to  make  them  work 
to  his  advantage,  the  first  condition  is,  that  he  shall  thoroughly  under- 
stand them. 

It  must  be  remarked,  in  the  first  place,  that  the  mass  of  surplus  water 
forming  a  flood  is  not  actuated  with  the  same  speed  over  all  its  width. 
The  nearer  the  liquid  particles  are  to  the  bank,  the  slower  they  move. 
This  phenomenon,  caused  by  the  friction  of  the  fluid  against  its  banks 
and  the  bottom  of  its  bed,  may,  it  is  true,  be  observed  to  some  extent  at 
low- water  seasons  as  well ;  but  it  is  when  the  level  of  the  river  is  at  the 
highest  that  the  various  portions  of  the  liquid  mass  present  the  greatest 
differences  in  speed.  The  thread  of  the  current^  the  mathematical  line  of 
the  greatest  rapidity,  which  varies  every  ^lay  and  in  every  stream,  ac- 
cording to  the  quantity  of  water  and  the  section  of  its  bed,  exceeds  by 
about  a  fifth  the  average  speed  of  the  river.*  In  flood-times  this  line 
gradually  rises  above  the  bottom,  and  by  thus  ascending  toward  the  sur- 
face of  the  river,  so  as  to  keep — according  to  the  direction  or  forces  of 
the.wind — sometimes  on  the  surface  of  the  river,  sometimes  a  few  feet  be- 
low, it  leaves  the  solid  walls  which  constitute  the  sides  of  the  river,  and 
the  medial  part  of  the  water,  of  which  it  is  the  ideal  axis,  and  moves  con- 
sequently with  greater  facility.  In  great  rivers,  such  as  the  Amazon,  the 
Mississippi,  or  the  Rhone,  the  current  sometimes  descends  with  the  speed 
of  seven  or  eight  miles  an  hour.  While  the  central  part  of  the  current 
thus  hastens  down  toward  the  sea,  the  water  at  the  side,  kept  back  by 
the  irregularity  of  the  bed,  remains  behind,  and  flows  more  slowly  along 
the  banks.  Thanks  to  this  difference  in  speed,  which  increases  accord- 
ing to  the  height  of  the  river,  floods  are  sometimes  lessened  or  even  en- 
tirely prevented.  In  fact,  when  mighty  masses  of  water,  descending  ei- 
*  According  to  M,  de  Prony,  it  is  0"1835. 


326 


THE  EARTH. 


ther  from  the  clouds  or  the  mountains,  fall  simultaneously  into  the  basin 
of  a  stream,  these  liquid  avalanches  would  certainly  produce  formidable 
inundations  if  they  were  not  immediately  carried  away  by  the  centre  of 
the  current,  and  did  not  distribute  in  succession  a  portion  of  their  bulk 
over  all  the  points  that  they  traverse.  Forming,  so  to  speak,  a  river  in 
the  middle  of  a  river,  this  rapid  flow  weakens  the  flood  by  dividing  it 
over  a  vast  length  of  bank.  In  the  river  of  the  Ohio  the  mid-flow  has 
rolled  down  for  a  distance  of  five  miles,  when,  at  a  spot  two  miles  and  a 
half  from  the  very  place  where  the  rain  fell,  the  high  banks  are  scarcely 
touched  by  the  rising  water. 

In  consequence  of  the  speed  communicated  to  the  mid-flow  of  the  flood, 
the  liquid  mass  that  it  carries  along  is  perceptibly  higher  than  the  mean 
level  of  the  river.  It  forms  a  kind  of  convexity,  from  the  top  of  which 
the  water  spreads  out  in  light  sheets  toward  the  two  banks ;  but,  on  the 
other  hand,  when  the  flood-wave  has  disappeared,  the  middle  of  the  river 
exhibits  a  considerable  depression,  and  the  water  which  has  gradually  ac- 
cumulated near  the  two  edges  has  to  flow  back  toward  the  centre  of  the 
current,  so  as  to  re-establish  by  degrees  the  fluviatile  level.     It  has  been 


Fig.  125.  Subsidences  of  the  Waters. 

ascertained  that  on  the  Mississippi  the  central  convexity  of  the  flood-wave 
is  on  the  average  about  three  feet.  When  the  river  sinks,  almost  as  con- 
siderable alteration  of  the  level  takes  place  in  a  contrary  direction.  The 
wood-cutters  of  Maine  and  Canada  are  not  ignorant  of  this  hydrological 
fact.  They  are  well  aware  that  logs  of  timber  thrown  into  the  river  in 
flood-time  are  thrown  up  on  the  banks,  while  they  float  regularly  down 
the  middle  of  the  current  when  the  river-level  sinks.* 

The  depression  which  is  formed  in  the  middle  of  the  river  during  the 
period  of  subsidence  is,  however,  obliterated  as  soon  as  the  liquid  mass 
ceases  to  diminish ;  the  water  then  commences  to  bulge  up  again  in  the 
axis  of  the  current,  owing  to  the  greater  facility  of  movement  possessed 
by  it  in  that  part.  '  The  surface  of  those  great  Russian  rivers  which  are 
covered  with  ice  for  several  months  of  the  year  exhibits  a  remarkable  in- 
stance of  the  bulging  up  of  the  liquid  mass  in  the  central  line  of  the  cur- 
rent. At  the  conclusion  of  the  winter,  when  the  water  from  the  melting 
snow  runs  down  off"  the  banks  toward  the  bed  of  the  river,  and  the  sheet 
of  ice  stretched  over  the  river  is  not  yet  broken,  it  is  ascertained  that  the 
surface-water  collects  in  elongated  pools  on  those  portions  of  the  field  of 
ice  which  are  nearest  to  the  edges,  while  the  medial  part  bulges  up  in  an 
arch  above  the  current,  and  remains  constantly  dry.  On  the  Volga,  the 
*  Marsh,  Man  and  Nature. 


SESULTH  OF  FLOODS.  327 

difference  of  the  level  between  the  edges  and  the  middle  of  the  ice 
amounts  sometimes  to  more  than  three  feet.* 

The  current  is  not  the  only  regulating  force  which  weakens  the  action 
of  floods,  and  gives  more  certainty  to  the  height  of  the  water.  There  are 
other  agents  which  assist  in  equalizing  the  discharge  of  a  river  by  receiv- 
ing the  overflow  during  the  rainy  seasons,  and  afterward  emptying  it 
into  the  principal  current.  These  regulating  agents  are  the  surface  or  un- 
der-ground reservoirs  which  exist  on  each  side  of  water-courses  which  are 
still  left  in  a  state  of  nature.  Thus,  according  to  Humboldt,  the  Upper 
Maranon  pours  into  the  caverns  of  the  pongo  of  Manseriche  a  portion  of 
its  waters,  and  also  all  the  drift-wood  which  it  brings  down  from  the 
higher  valleys.  Many  streams  lose  a  considerable  quantity  of  water  by 
the  mere  process  of  filtration,  through  the  spongy  soil  of  their  valleys. 
It  is  stated  that  in  some  places  the  water  of  the  Nile  penetrates  laterally 
as  far  as  fifty  miles  from  the  bed  of  the  river.f  In  like  manner,  during 
floods,  the  Seine  feeds  the  land-springs  which  extend  under  Paris,  and  all 
the  wells  are  then  filled  by  the  water  of  the.  river.  J 

Next  to  lakes,  which  are  the  chief  regulators  of  running  waters,§  the 
marshes  lying  close  to  the  edges  of  a  river  take  the  principal  share  in 
modifying  its  discharge.  During  inundations  the  lagoon  and  swamps  on 
both  sides  temporarily  store  up  a  large  quantity  of  flood-water,  which  is 
only  set  free  after  the  sinking  of  the  river.  The  marshy  regions  through 
which  the  Mississippi  runs  in  its  middle  course  affords  a  remarkable  in- 
stance of  this  fact.  Thus,  in  1858,  the  great  American  river,  which  be- 
low the  mouth  of  the  Ohio  sent  down  52,039  cubic  yards  of  water,  only 
discharged  45,915  yards  at  Baton  Rouge,  after  it  had  received  the  con- 
tents of  the  Arkansas,  the  Yazoo,  and  other  less  important  rivers.  A 
mass  of  water,  amounting  to  6124  cubic  yards  a  second — equivalent  to 
nineteen  times  the  bulk  of  the  Seine — must,  therefore,  have  been  lost  on 
the  way.  II  Just  in  the  same  way,  the  Rhone,  in  its  great  inundations, 
makes  its  way  over  the  side  embankments  opposite  Culoz,  and,  covering 
the  whole  of  the  vast  marsh  of  the  Chautagna,  pours  its  surplus  waters 
into  the  Lake  of  Bourget.  It  has  been  calculated  that  during  the  flood 
of  1863  this  reservoir  absdl-bed  from  the  Rhone  a  mass  which  altogether 
amounted  to  71,900,000  cubic  yards  of  water,  the  effects  of  which  would 
have  been  most  disastrous  on  the  plains  below.  1^ 

In  places  where  the  marshes  beside  a  river  have  been  drained  by  the 
operations  of  man,  the  water-level  of  the  stream  rises  to  a  much  more  con- 
siderable height  in  flood-time,  and  the  plains  around  are  inundated.  But 
the  inundations  themselves  become  new  regulators  of  the  discharge  of  the 
water,  and  that,  indeed,  by  means  of  their  very  irregularity.     The  liquid 

*  De  Bncr,  Bulletin  de  rAcademie  de  St.  Petersbourg,  vol.  vii.,  No.  4. 
t  Marsh,  Man  and  Nature. 

t  Delesse,  Carte  Hydrologique.  §  Vide  the  chapter  on  "Lakes." 

II  Humphreys  and  Abbot,  Report  on  the  Mississippi  River. 
^  Gobin,  Commission  Hijdromitrique  de  Lyon,  1862. 


328  2!H2r  EARTH. 

sheet  which  covers  the  fields  is  hindered  in  its  flow  by  the  inequalities  of 
the  ground  and  by  clumps  of  trees.  Being  unable  to  follow  the  river  in 
its  impetuous  course,  it  remains  behind,  like  a  temporary  lake,  until  the 
river  is  low  enough  for  it  to  return  into  its  natural  bed.  Thus  the  flow 
of  an  inundation  always  decreases  in  height  as  it  gets  nearer  to  the  sea, 
and  ultimately  it  completely  disappears.  The  inundation  of  the  Nile 
diminishes  as  it  flows  on  from  Assouan,  where  it  is  from  53  to  66  feet  in 
height,  to  Rosetta  and  Damietta,  where  it  is  not  more  than  three  feet  in 
height.  A  similar  decrease  in  the  flood-wave  may  be  observed  on  all 
other  rivers.  We  must  not,  however,  lose  sight  of  the  fact  that  this 
gradual  waste  of  the  water  proceeds  partly  from  several  other  causes, 
such  as  the  porous  nature  of  the  ground  bathed  by  the  river,  the  activity 
of  the  vegetation  growing  by  its  side,  and  the  amount  of  evaporation. 
This  last  cause  of  the  exhaustion  of  the  water  is  probably  the  most  igi- 
portant  in  all  hot  countries  like  Egypt  and  Guinea. 

It  should  be  man's  part  to  complete  the  work  of  Nature  by  imitating  in 
his  operations  some  of  those  means  which  she  employs  for  storing  up  sur- 
plus waters,  and  afterward  distributing  them  equally  over  vast  areas,  thus 
insuring  a  regular  discharge.  Man  should  make  it  his  task  to  watch  the 
drop  of  rain  as  it  falls  from  the  sky,  to  follow  it  in  its  course,  to  arrest  it 
in  its  progress  when  it  would  help  to  swell  a  dreaded  flood,  and  to  em- 
ploj-  it  for  the  benefit  of  agriculture,  navigation,  and  manufactures.  On 
every  mountain-side  and  elevated  plateau  he  may  avail  himself  of  a  pow- 
erful remedy  for  the  prevention  of  floods,  by  replanting  them  with  trees ; 
for,  as  M.  Becquerel's  experiments  have  proved,  the  quantity  of  water 
which  drops  during  heavy  rain  on  wooded  ground  is  only  six  tenths  of 
that  which  falls  on  the  bare  soil.*  In  a  great  number  of  the  upper  val- 
leys reservoirs  might  be  constructed,  where  the  liquid  mass  would  accu- 
mulate in  times  of  rain,  and  be  subsequently  emptied  over  the  slopes  in 
innumerable  irrigating  conduits.  On  cultivated  declivities,  as  Provence 
and  the  Maritime  Alps,  man  should  enlarge  and  consolidate  the  flat  stages 
which  rise  one  above  another  along  the  mountain-sides,  forming,  as  it 
were,  so  many  staircases,  each  step  of  which  should  keep  back  its  share 
of  rain-water.  In  the  valleys  he  should  tap  the  river  in  order  to  feed  ir- 
rigation ditches  and  mill  streams.  Finally,  in  the  lowland  plains,  it  would 
be  easy  to  line  each  side  of  the  river  with  reservoirs,  where  the  stream 
might  deposit  the  sediment  with  which  it  is  charged. 

The  streams,  on  the  sides  of  which  water-mills  and  manufactories  have 
been  established,  are,  as  it  were,  disciplined  by  means  of  the  waste  water 
channels  and  the  reservoirs  where  the  water  is  stored  up,  and  especially 
through  the  mill-dams  and  other  obstacles  which  convert  the  river  or 
stream  into  a  regular  canal,  with  its  dammed-up  levels.  Inundations  are^ 
therefore,  very  rare,  or  even  quite  unknown,  in  a  great  number  of  the 
manufacturing  valleys  of  England,  Scotland,  and  the  United  States. 
Still,  the  gratuitous  power  aflforded  by  water  is  not  by  any  means  genei'- 
*  Comptes  Rendus  de  F Academic  des  Sciences,  November  5, 1866. 


LAKE  M(ERIS.  329 

ally  utilized  at  present ;  and  oven  the  inhabitants  of  manufactnring  coun- 
tries allow  a  very  considerable  quantity  of  available  water-power  to  run 
away  to  waste.  Thus — to  select  an  instance  among  the  French  streams 
which  turn  the  greatest  number  of  mill-wheels — the  Doubs  itself,  flowing 
through  the  manufacturing  d.\sivict%  par  excellence^  scarcely  does  one  quar- 
ter of  the  work  which  might  be  obtained  from  it.  From  Vougeaucourt 
to  Be8an9on,  a  distance  of  43  miles,  the  total  fall  being  248  feet,  only 
900,000  horse-power  was  utilized  ih  1860,  out  of  the  total  amount  of 
3,400,000  horse-power  which  might  have  been  employed. 

Although  manufacturing  operations  can  only  assist  exceptionally  in 
moderating  and  gradually  doing  away  with  floods,  the  agricultural  proc- 
esses which  are  going  on  in  all  the  valleys  inhabited  by  man  ought  to 
exercise  a  direct  and  decisive  influence  in  regulating  the  flow  of  streams 
and  rivulets.  The  husbandman  ought  not  to  allow  the  waste  of  a  single 
drop  of  the  beneficent  water,  which,  by  a  widely-extended  system  of  irri- 
gation, might  double,  or  even  increase  tenfold,  his  crops,  and  convert  a 
wilderness  into  a  garden.  In  the  intelligent  employment  of  running  wa- 
ter in  the  fertilization  of  a  district,  our  agriculturists  have  much  to  learn 
from  the  example  of  the  ancients.  As  far  back  as  the  time  of  the  early 
Egyptians,  works  of  irrigation  of  really  colossal  dimensions  had  been  ac- 
complished; and  perhaps,  among  all  the  undertakings  of  this  kind  due  to 
modern  industry,  there  is  not  one  which,  in  boldness  of  plan  or  practical 
utility,  can  be  said  to  surpass  the  meri  (basin),  or  Lake  Moeris,  which  was 
opened  to  the  waters  of  the  Nile  in  the  reign  of  Pharaob  Amenemha  III., 
more  than  4500  years  ago,  according  to  the  chronology  of  M.  Brugsch. 

From  the  topographical  details  which  have  been  left  by  ancient  authors 
as  to  this  wonder  of  the  world,  we  know  that  the  site  of  Lake  Mceris  must 
be  looked  for  in  the  present  province  of  Fayoum,  the  name  of  which  is  de- 
rived from  the  Coptic,  and  signifies  sea.  Now,  a  considerable  lake  exists 
at  the  present  time — the  Birket  el  Keyroun — in  the  lowest  part  of  the 
province ;  and  so  long  as  the  geography  of  this  part  of  Egypt  was  but 
partially  known,  it  was  very  natural  to  look  upon  this  lake  as  the  ancient 
excavation  of  the  Pharaohs.  A  study  of  tlve  localities  has  proved  that 
this  is  not  the  case.  In  fact,  the  Birket  el  Keyronn  is  situated  in  a  deep 
depression,  nearly  on  the  level  with  the  sea,  and  53  feet  below  the  aver^ 
age  waters  of  the  Nile.  This  basin,  therefore,  can  not  be  the  one  which 
alternately  received  the  surplus  flood-water  of  the  river  and  emptied  it 
out  again  through  two  wide  gates,  as  Strabo  tells  us,  into  the  plains  by 
the  side  of  the  Nile.  Besides,  the  position  of  this  lake  difiers  much  from 
that  which  the  ancient  geographers  assigned  to  the  Moeris.  According 
to  the  discoveries  of  M.  Linant  de  Bellefonds,  the  engineer,  the  site  of  the 
great  reservoir  was  just  in  the  very  highest  part  of  Fayoum,  to  the  west 
of  the  rocky  gorge  of  Illaoun,  through  which  flows  a  natural  side-chan- 
nel of  the  Bahr  Yousef,  which  probably,  at  some  former  geological  period, 
was  the  principal  current  of  the  Nile.  Fragments  of  a  long  dike,  which 
in  some  places  is  not  less  than  30  feet  high  and  200  feet  wide,  may  still  be 


330 


THE  EARTH. 


met  with  in  the  eastern  part  of  Fayoura.  It  must  once  have  constituted 
a  semi-circular  rampart,  spreading  round  the  outlet  of  the  great  basin 
of  the  Fayoum  plains,  and  have  penned  back  the  water  brought  by  the 
Bahr  Yousef 

M.  Linant  -has  calculated  that,  during  the  hundred  days  of  flood,  this 
branch  of  the  river,  which  represents  on  an  average  about  the  twenty- 
eighth  part  of  the  Nile,  emptied  into  the  basin  a  quantity  of  water  equal 
to  466  cubic  yards  a  second,  and  that  the  total  mass  of  water  contained 
in  this  gigantic  reservoir,  even  after  making  allowance  for  evaporation, 
could  not  have  been  less  than  3,694,000,000  cubic  yards.  This  was  suf- 
ficient to  diminish  very  considerably  the  dangers  resulting  from  the  in- 
undations of  the  Nile,  and  subsequently  to  afford  all  the  water  that  was 


Fig.  126.  Map  of  Fayoum. 

requisite  for  the  irrigation  of  444,000  acres.  According  to  the  statement 
of  Herodotus,  the  surplus  waters  spread  out  to  the  west  toward  the 
Syrtes  of  Libya ;  that  is  to  say,  after  crossing  the  lake,  which  is  called 
Birket  el  Keyroun,  it  filled  the  bed  of  a  channel  now  dried  up,  which  car- 
ried the  waters  of  the  Nile  into  the  western  deserts.  At  the  present  day, 
Fayoura  still  possesses  a  magnificent  system  of  irrigation,  which  may  be 
compared  to  the  ramifications  of  the  arteries  and  blood-vessels  of  a  liv- 
ing being ;  but  forty-five  centuries  ago.  Lake  Moeris,  which  constantly 
changed  its  level  according  to  the  needs  of  agriculture,  was  like  a  heart 
from  which  the  flow  of  life  was  shed  out  to  nourish  the  great  body  of 
Egypt  as  far  as  distant  Memphis.  Nothing  now  remains  of  Moeris  but 
the  broken-down  dikes,  a  few  fragments  of  the  two  pyramids  which  were 


IRRIGATION  CHANNELS.  331 

built  up  in  its  waters  to  the  glory  of  Ameneraha,  and  a  thick  layer  of  al- 
luvium deposited  on  its  basis  by  the  troubled  waters  of  the  Bahr  Yousef.* 
Among  European  rivers,  the  Po  is  that  which  may  be  best  compared 
to  the  Nile  of  the  ancients,  as  regards  the  care  with  Avhich  its  watera 
have  been  utilized  for  the  fertilization  of  the  soil.  So  far  back  as  1863, 
the  Lombard  agriculturists  required  for  the  watering  of  their  crops 
59,000,000  of  cubic  yards  of  water  a  day,  equal  to  681  yards  a  second; 
that  is,  a  liquid  mass  equivalent  to  the  average  discharge  of  the  Seine 
during  the  same  period.f  Since  the  above  date,  the  great  Cavour  canal 
has  been  opened — a  perfect  artificial  river — which  requires  for  itself  alone 
144  cubic  yards  of  water  a  second.  Starting  from  Chivasso,  below  Turin, 
this  river,  which  is  not  less  than  55  yards  wide  at  its  commencement, 
spreads  its  fertilizing  water  on  both  sides  in 'the  already  fertile  plains  of 


,\a.i<Tof  flicMk 


Fig.  127.  Section  across  Fayoum. 

Lomellina;  it  receives,  en  route,  numerous  streams — the  Elvo,  the  Sesia, 
the  Agogna,  the  T^erdoppio  —  and  at  Turbigo-  empties  into  the  Tesino 
all  that  remains  of  its  liquid  mass,  after  having  irrigated  more  than 
494,000  acres.  Next  to  the  great  canal  of  the  Ganges,  in  Hindostan,  it 
is  the  most  important  operation  of  this  kind  accomplished  in  modem 
times.  There  can  be  no  doubt  that  the  Po,  once  so  dreaded  on  account 
of  its  sudden  floods,  will  ultimately  become,  in  conjunction  with  the  other 
water-courses  of  Lombardy,  a  scientifically  arranged  system  of  agricul- 
tural canals. 

Agriculturists  should  not  only  employ  the  water  of  torrents  and  streams 
for  increasing  their  crops  and  nourishing  the  soil,  but  they  should  also 
make  use  of  the  sediment  and  debris  of  all  kinds  which  are  washed  away 
by  the  water  from  their  up-stream  banks.  As  an  instance,  let  us  take  the 
Durance,  a  French  river,  which  has  been  thoroughly  surveyed  and  studied 
to  ascertain  the  plan  for  utilizing  its  water  and  mud  for  the  irrigation 
and  manuring  of  the  plains  by  the  river-side.  The  eighteen  channels 
which  are  fed  by  this  stream  can  draw  from  it  as  much  as  90  cubic  yards 
a  second ;  so  that  at  any  time  when  the  whole  of  this  liquid  mass  is  being 

*  Linant  de  Bellefonds,  Mimoire  sur  le  Lac  Maeris. 

t  Elia  Lombardini,  Politecnico,  January-,  1863,  quotetl  by  Mareh. 


332  '^^^  EARTH. 

taken  away  at  once,  only  30  cutic  yards  remain  in  the  bed  of  the  Du- 
rance in  low  water  seasons,  or  about  a  quarter  of  its  regular  discharge. 
According  to  the  observations  of  M.  Herve-Mangon,  which  lasted  from 
the  1st  of  November,  1859,  to  the  31st  of  October,  1860,  the  mass  of  mud 
brought  down  by  the  stream  during  the  whole  year  represents  a  quan- 
tity of  near  18,000,000  tons.  Some  idea  may  be  formed  of  the  enormous 
bulk  of  the  mud  which  is  washed  away  every  year  by  the  Durance  from 
the  upper  portion  of  its  basin,  by  picturing  this  mass  in  the  form  of  a  cube 
242  yard«  on  each  side ;  if  spread  out  uniformly  on  the  ground  this  allu- 
vium would  cover  in  a  year  more  than  108,000  acres,  with  a  layer  an  inch 
thick,  containing  in  a  form  of  combination  most  suitable  to  the  plants 
more  azote  than  100,000  tons  of  guano,  and  more  carbon  than  121,000 
acres  of  forests  (?).  Unfortunately,  as  these  canals  are  constructed  with 
a  view  to  irrigation  only,  nine  tenths  of  the  mud  is  lost  for  manuring  pur- 
poses ;  and  the  farmers  purchase,  at  the  cost  of  many  thousand  pounds  a 
year,  the  very  elements  of  fertilization  which  their  stream  washes  down 
into  the  Mediterranean,  although  they  might  so  easily  avail  themselves 
of  them. 

As  every  river  possesses  its  own  special  peculiarities,  the  regulating 
works  which  the  engineers  have  to  undertake  for  the  purpose  of  doing 
away  with  floods  and  distributing  the  water  discharge,  must  be  contrived 
in  different  ways,  according  to  the  form  and  capacity  of  the  upper  mount- 
ain hollows,  the  rapidity  of  the  current,  the  suddenness  of  the  floods,  the 
porosity  of  the  ground  by  the  river-side,  and  the  extent  of  the  forests 
which  clothe  the  hill-sides.  The  operation  of  regulating  the  discharge 
of  a  water-course  is  certainly  very  difficult  to  accomplish ;  in  some  river- 
basins  it  would  require  the  labor  of  several  generations;  but  suffice  it  to 
say,  it  is  not  impossible,  aad  that  it  has  already  been  ^ccessfully  carried 
out  in  many  parts  of  the  globe.  Although  the  greater  part  of  the  rivers, 
in  both  Europe  and  the  civilized  portion  of  America,  have  up  to  the  pres- 
ent time  remained  free  from  man's  guidance,  and  still  occasionally  devas- 
tate the  cities  and  cultivated  districts  which  lie  upon  their  edges,  there 
are  at  least  a  few  of  which  the  floods  have  been  rendered  harmless, 
thanks  to  the  labor  of  the  frightened  inhabitants.  Among  the  rivers 
which  were  once  most  dangerous,  and  are  now  almost  entirely  subdued, 
yfe  may  mention  the  Arno,  which  has  been  looked  after  for  centuries  by 
the  skillful  Tuscan  engineers.  At  one  time  this  river  was  most  formida- 
ble, on  account  of  its  periodical  inundations.  From  the  year  1400  to 
1761,  no  less  than  thirty-one  disasters  of  this  kind  are  recorded.  Since 
1761 — the  date  when  the  improvements  of  the  river  were  carried  out — 
until  1835,  there  has  not  been  a  single  serious  flood.*  The  Po  itself— the 
river  which  in  flood-time  hangs  suspended,  so  to  speak,  over  the  surround- 
ing plains — is  now  much  less  to  be  dreaded  than  heretofore,  thanks  to  the 
ii-rigating  channels  which  tap  it,  and  also  to  the  lateral  embankments 
which  border  the  whole  of  its  lower  course  below  Cremona.f 
*  Marsh,  Man  and  Nature.  t  Vide  p.  335. 


EMBANKMENTS. 


333 


In  this  stream,  as  in  a  great  many  others,  the  sui-plus  waters  of  the 
high  floods  come  down  too  rapidly,  and  in  masses  too  considerable,  to 
afford  any  possibility  of  storing  thera  up,  or  of  turning  them  off  in  a 
lateral  direction  without  devastating  the  plains.  It  is  necessary  that  the 
inhabitants  should   protect   themselves  by  well -planned   constructions 


Fig.  12S.  Dikes  along  the  Rhine  near  Seltz. 

against  the  threatening  pressure  of  the  water.  The  Egyptians  dwelling 
in  the  Delta  built  their  cities  on  artificial  hillocks  above  the  level  of  the 
annual  floods.  The  inhabitants  of  some  parts  of  Holland,  wishing  to  fa- 
cilitate the  "warping"  of  the  fields,  elevate  their  habitations  above  the 
ground,  and  the  houses  become  so  many  islands  in  the  midst  of  the  floods. 
In  recently  colonized  countries,  where  man's  first  care  is  to  protect  his 
habitation,  all  he  does  at  first  is  to  construct  a  circular  embankment 


334  T^^  EAMTir. 

round  the  town  or  village.  This'was  the  procedure  of  the  French  colo- 
nists after  tliey  had  jjlanted  the  first  pile-work  of  New  Orleans.  The 
Americans,  too,  adopted  this  plan  of  protection  for  the  Californian.city, 
Sacramento,  and  the  warehouses  at  Cairo,  situated  at  the  confluence  of  the 
Ohio  and  the  Mississippi.  In  like  manner,  the  towns  on  the  banks  of  the 
Loire  are  protected  against  the  flood-wave  by  walls.  Added  to  this, 
when  the  banks  of  a  water-course  are  covered  by  cultivated  fields,  and 
the  inundation  would  prove  fatal  to  them — as  in  Louisiana,  Lombardy, 
China,  and  many  other  countries  in  the  temperate  zone — it  is  necessary 
to  raise  longitudinal  dikes  on  the  edges  of  the  streams  which  at  flood- 
time  are  higher  in  their  level  than  the  surrounding  plains.  Thus  shut  in 
between  their  dikes,  rivers  are  compelled  to  give  up  their  wandering 
couree,  and  to  flow  down  to  the  sea  through  the  channel  which  has  been 
traced  out  for  them.  These  longitudinal  embankments,  which,  at  any 
rate,  are  no  ornament  to  nature,  are  sometimes  a  matter  of  absolute  ne- 
cessity; but  if  the  constructors  wish  to  prevent  their  dikes  being  broken 
through,  and  to  avert  the  disasters  which  are  the  certain  consequence  of 
cracks,  they  must  calculate  beforehand  the  force  of  the  liquid  mass  with 
which  they  will  have  to  contend  during  extraordinary  floods ;  and  they 
must  build  their  ramparts  of  materials  sufficiently  solid  to  resist  without 
difficulty  the  lateral  pressure  of  the  water.  They  must  likewise  carefully 
protect  their  dikes  against  burrowing  animals,  for  the  embankments  of  the 
Po  have  several  times  been  perforated  by  moles,  and  those  of  the  Missis- 
sippi by  musk-rats.  It  is  necessary,  also,  to  give  the  embankments  a  gen- 
tle bend,  and  to  leaye  a  sufficient  width  for  the  penned-in  river.  The 
Loire,  in  front  of  Orleans,  was  once  3827  yards  wide,  but  has  been  re- 
duced by  the  embankments  to  a  bed  of  306  yards.  At  Jargeau,  it  is  only 
273  yards  wide  at  a  place  where  it  once  had  a  lateral  spread  of  7650 
yards.  In  1856  the  Loire  burst  twenty-three  breaches  through  these 
banks,  which  were  said, to  be  imjjenetrable  ;*  as  soon  as  the  height  of  the 
flood  rose  in  the  river  to  more  than  16^  feet,  ci-acks  became  inevitable. 
The  losses  occasioned  by  the  breaking  down  of  these  too  feeble  ramparts, 
over  Avhich  the  flood-water  rushed  like  a  deluge,  were  so  considerable 
that  the  question  was  often  asked  whether  it  would  not  be  better  to 
throw  the  dikes  down  entirely  and  to  replace  them  with  plantations  of 
trees.  The  water,  flowing  without  difficulty  through  the  open  barrier  of 
the  crowded  trunks,  would  be  distributed  equally  over  the  plains  by  the 
river-side,  and  would  consequently  never  rise  to  the  formidable  height 
which  it  reached  between  the  dikes.  Added  to  this,  its  annual  ravages 
would  be  in  great  part  compensated  for  by  the  fertile  alluvium  which 
would  be  deposited  by  the  sediment  with  which  the  water  is  charged. 
It  has  been  calculated  that  if  the  vast  basin  of  the  Saone,  situated  above 
the  gorge  of  Pierre-Encise,  were  protected  against  the  inundations  of  the 
river  by  means  of  dikes,  confining  the  water  to  a  bed  273  yards  wide,  the 
same  as  at  Lyons,  a  liquid  mass  of  1,869,000,000  cubic  yards,  which,  during 
*  Champion,  Inondations  de  la  France, 


EMBANKMENTS  OF  THE  PO. 


330 


inundations  like  those  of  1840,  now  spreads  over  the  plains,  would  then 
rush  down  upon  the  town  in  the  space  of  a  few  days.  On  the  other  side  of 
Lyons  the  Rhone  affords  a  remarkable  instance  of  the  influence  which  the 
dimensions  of  the  bed  exercise  on  the  height  of  the  flood.  In  1856,  in  the 
wide  plain  of  Miribel,  seven  miles  and  a  half  above  Lyons,  the  flood-wa- 
ter rose  only  nine  feet  and  a  half;  but  it  rose  to  20  feet — that  is,  more 
than  double — in  the  narrow  bed  contained  between  Lyons  and  the  Brot- 
teaux.*  In  the  valley  of  the  Isere,  the  mean  height  of  the  flood-waters 
has  undoubtedly  risen  since  the  construction  of  the  side  embankments, 
which  were,  in  fact,  placed  too  close  to  one  another.  This  has  been 
proved  by  the  very  exact  observations  of  M.  Dausse. 

The  embankments  of  the  Po,  more  scientifically  constructed  than  those 
of  the  Isere,  were  commenced  many  centuries  ago,  when  the  long  night 
of  the  Middle  Ages  still  darkened  the  rest  of  Europe.  At  a  point  below 
Cremona,  whei*e  the  continuous  line  of  dikes  commences,  they  are  very 
•wide  apart,  but  the  space  through  which  the  flood-waters,  can  flow  is 
gradually  narrowed  in  down  to  the  mouth  of  the  river;  from  65(34  yards 


JanMPT 

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Fig.  129.  Mean  Heights  of  the  Isere. 

it  diminishes  to  3000,  2000,  and  even  1000  yards.  IJltimately  each  of 
the  branches  of  the  delta  is  not  more  than  300  to  500  yards  wide  be- 
tween the  inclosing  embankments.  The  fact  is,  that  a  great  portion  of 
the  mass  of  water,  finding  between  its  upper  dikes  so  considerable  a 
space  over  which  it  is  able  to  spread  freely,  remains  stored  in  the  plains 
above,  and  thus  the  flood-water  tends  constantly  to  diminish  in  a  down- 
stream direction.  The  flat  districts  that  lie  between  the  dikes  are  called 
galenas.  Each  land-holder  may  cultivate  them  and  embank  them  as  he 
likes;  but  on  the  condition  that  his  dikes  shall  be  always  nearly  six  feet 
lower  than  the  principal  embankments,  so  as  not  to  offer  any  serious  ob- 
♦  Gobin  ;  L'Eveille,  Commission  Hydromitrique  de  Lyon,  18G3. 


336 


THE  EARTH. 


stacles  to  high  inundations.  These  golenas^  therefore,  with  their  dikes 
all  round  them,  form  so  many  settling  reservoirs  where  the  alluvium  ac- 
cumulates after  each  fresh  flood,  and  their  level  is  much  higher  than  the 
plains  outside  the  dikes.*  Owing  to  the  care  with  which  the^e  embank- 
ments are  kept  up  by  the  syndicate  of  the  river-side  proprietors,  cracks 
in  them  are  very  rare.  Since  1705,  the  date  at  which  a  breach  of  more 
than  50  miles  took  place  below  Cremona,  the  reconstructed  portion  of 
this  enormous  rampart  has  not  yielded  at  any  point.     Although  lower 


Fig.  130.  Dikes  by  the  Po,  IVoiu  Oiemoua  to  Ihe  Sea. 


down  the  river  extraordinary  inundations  still  occasionally  break  through 
the  lateral  embankments  in  some  few  places,  any  great  disaster  is  in  a 
measure  prevented  by  the  side  channels,  opened  on  both  sides  of  the 
river,  in  the  delta  of  the  Po.  Nevertheless,  the  system  is  not  yet  perfect. 
M.  Lombardini  thinks  it  very  important  that  in  the  lower  part  of  the 
river  a  considerable  space  should  be  left  open  to  the  flood-waters,  so  that 
the  alluvium  might  be  distributed  on  the  plains  on  each  side,  instead  of 
throwing  out  a  promontory  into  the  Adriatic  Sea,  and  consequently  rais- 
ing the  bed  of  the  river. 

Next  to  the  embankments  on  the  Dutch  rivers,  those  of  the  Po  form 
the  most  remarkable  system  of  protection  against  inundations  that  has 
been  devised  in  Eui'ope ;  but  they  are  inferior  in  importance  to  the  em- 
bankments which  run  along  a  great  portion  of  the  Mississippi,  and  which, 
from  their  enormous  size  and  length,  form  a  source  of  admiration  to 
every  traveler.  On  the  right  bank  of  the  river,  from  Cape  Girardeau 
(Missouri)  to  the  Pointe-Jl-la-Hache,  situated  below  New  Orleans,  the  em- 
bankments form  a  wall  of  1125  miles  in  length,  only  interrupted  by  the 
mouths  of  rivers  and  a  few  spots  of  rising  ground.  On  the  left  bank,  the 
*  Elia  Lombardini,  Dei  Cangiamenti  del  Po. 


EMBANKME2TTS  OF  THE  MISSISSIPPI. 


337 


base  of  the  plateau,  which  the  Mississippi  here  and  there  touches,  has 
enabled  the  inhabitants  to  dispense  with  constructing  any  continuous 
dike ;  but  they  have  been  compelled  to  resort  to  embankments  for  pro- 
tecting all  the  plains  which  extend  from  Memphis  to  Vicksburg,  and 
from  Baton  Rouge  to  New  Orleans.  The  ramparts  that  have  been  raised 
on  the  eastern  bank  are  altogether  more  than  625  miles  in  length,  and 
some  of  them  are  of  very  considerable  dimensions ;  that  which  has  been 
constructed  at  Yazoo-gate,  in  order  to  close  a  bayou*  of  the  Mississippi, 
is  no  less  than  42  feet  in  height,  42  feet  in  width  at  the  top,  and  31V  feet 
broad  at  the  base.  To  these  immense  constructions  we  must  add  all  the 
embankments  formed  along  the  tributaries  of  the  Mississippi  and  the 
hayous  of  its  delta;  we  must  likewise  take  account  of  all  the  double  and 


Pig.  131.  Golfiiai  by  llie  I'o. 

triple  parallel  dikes  which  have  been  raised  in  some  of  the  spots  which 
are  most  exposed  to  the  action  of  the  river.  The  whole  of  the  embauK- 
ments  of  the  Mississippi  must  altogether  reach  a  total  length  of  at  least 
2500  miles.  It  is  true  that  in  many  of  these  imposing  ramparts  there  is 
still  much  to  be  wished  for  in  respect  to  solidity. 

Every  great  flood  on  the  Mississippi  which  has  been  recorded  has 
formed  one  or  more  breaches  in  the  embankments  above  New  Orleans. 
The  water  then  rushes  like  a  cataract  into  the  plains  which  extCTid  below 
its  level  to  a  depth  of  10,  12,  and  even  15  feet.  It  rapidly  enlarges  the 
opening  by  washing  down  the  dikes  for  an  extent  of  one  or  more  miles, 
and  then,  digging  deep  into  the  soil,  hollows  out  for  itself  a  ilew  bed 
across  the  plantations.  One  of  these  temporary  beds  which  the  river 
made  in  1850,  1859,  and  1862,  near  the  hamlet  of  Bonnet  -  Carre,  dis- 
charged no  less  than  3930  cubic  yards  of  water  a  second — that  is,  a  sixth 

Vide  foot-note,  p.  347. 

Y 


338 


THE  EARTH. 


of  the  average  liquid  mass  of  the  Mississippi.  If  the  inhabitants  liad  not 
succeeded  in  stopping  it  up  on  each  occasion,  the  new  river  would,  with- 
out doubt,  have  gradually  become  one  of  the  branches  of  the  delta  of  the 
Mississippi  In  like  manner  the  Hoang-Ho,  having  burst  through  its  em- 
bankments, emptied  itself  into  the  sea,  partly  to  the  north  and  partly  to 


iiie  jfissbsipi  \\ 


«      /~H 


Fig.  132.  Gap  formed  near  New  Orleans. 

the  south  of  the  peninsula  of  Chantoung,  leaving  a  distance  of  217  miles 
between  its  two  mouths.  The  territory  exposed  to  its  ravages  was  not 
less  in  extent  than  the  whole  area  of  England.  According  to  a  tradition 
related  by  Ritter,  which,  however,  is  doubtless  exaggerated,  200,000  in- 
dividuals of  the  province  of  Honan  were  drowned  during  a  civil  war  in 
consequence  of  the  dikes  being  cut  throu^-h. 


DISAPPEARANCE  OF  RIVERS.  339 


CHAPTER  LH. 

THE    MOUTHS    OP   RIVERS. ESTUARIES. — LONG    BANKS    OP   SAND. DELTAS. 

— NET-WORK    OF    BRANCHES    OF    RIVERS   IN   ALLUVIAL   PLAINS. 

Below  its  confluence  with  its  last  tributary  a  river  can  not  fail  to  di- 
minish in  volume,  on  account  of  the  evaporation  of  its  water,  and  also  of 
infiltration  into  the  earth.  There  are,  indeed,  some  streams  which,  as  we 
have  seen,  gradually  waste  away  without  receiving  any  compensation  from 
tributaries  to  make  up  for  their  liquid  loss,  and  ultimately  entirely  dry  up. 
Xot  only  in  the  burning  regions  of  the  torrid  zone,  where  rains  are  rare, 
but  also  in  the  great  plains  of  the  temperate  zone,  wherever  the  surface  of 
the  ground  is  too  level  to  afford  an  incline  for  the  running  away  of  the 
water,  we  find  many  rivers  flowing  down  from  the  mountains,  and  then, 
failing  to  make  their  way  to  the  ocean  or  any  inland  sea,  they  disappear 
among  the  sands  of  the  level  country.  Thus  the  Rio  Dulce,  the  rivei*s 
Primo,  Segundo,  Quint'o,  and  several  other  water-courses  in  the  Argentine 
Republic,  come  to  an  end  amid  the  pampas  in  a  series  of  lagoons,  which 
rise  or  fall,  advance  or  retire,  in  the  desert,  according  to  the  seasons  of  the 
year  or  the  quantity  of  water.  Farther  up-stream  these  rivers  are  navi- 
gable for  boats,  and  sometimes  cover  the  country  round  with  their  floods; 
but  below  their  current  becomes  weakened,  they  break  up  into  pools,  and 
at  last,  becoming  little  more  than  liquid  mud,  they  fail  even  in  moistening 
the  soil  of  the  prairie.  In  a  similar  way  the  branch  of  the  delta  of  the 
Rhine,  which  retains  the  name  of  the  river,  disappeared  amid  the  sand- 
banks previously  to  1806,  the  date  at  which  a  canal  was  dug  thi'ough  the 
dunes,  and  was  protected  against  the  sea  by  efiicient  flood-gates. 

A  river,  however,  can  scarcely  be  considered  to  be  worthy  of  its  name, 
;^nd  can  play  no  important  part  in  history,  if  it  fails  to  send  down  its  wa- 
ter to  the  ocean  in  a  constant  and  regular  way.  Only  under  these  condi- 
tions is  it  accessible  to  ships,  and  in  a  position  to  connect  the  inland  dis- 
tricts with  those  of  the  sea-coast.  Just  as  a  tree,  the  trunk  of  which, 
formed  by  the  union  of  all  its  branches,  brings  into  communication  the  at- 
mosphere and  the  bowels  of  the  earth,  so  the  chief  trunk  of  the  river,  in 
which  all  its  aflluents  combine  their  liquid  mass,  links  the  sea  to  the  moun- 
tains and  to  the  plains.  By  its  ever-moving  flow,  by  the  junctions  of  its 
own  current  of  fresh  water  with  the  salt  waves  of  the  rising  tide,  it  brings 
together  all  parts  of  its  basin,  and  gives  life  and  energy  to  the  earth,  as 
the  blood  quickens  the  flesh  which  it  moistens. 

The  oceanic  portion  of  a  river  is  charsicterized  by  the  tides  which  twice 
every  twenty-four  hours  change  the  direction  of  its  current,  and  cause  the 
water  to  flow  back  upstream.     In  this  small  portion  of  its  development, 


340  ^^^  EARTH. 

the  action  of  a  stream  is  completely  modified ;  it  is  no  longer  a  water- 
course, nor  is  it  the  ocean.  It  is,  in  fact,  a  common  bed  where  the  two 
elements  meet  and  unite.  The  river-mouth  is  not  only  an  entrance  to  a 
continent  through  which  navigators  may  pass ;  it  also  opens  an  outlet  to 
the  sea-water,  and  enables  it  to  ascend  far  inland,  and  to  mingle  with  the 
liquid  mass  brought  down  by  the  river.  That  portion,  therefore,  of  the 
channel  where  the  junction  takes  place  between  the  salt  and  fresh  water 
constitutes  a  geographical  division  which  is  perfectly  distinct  from  all  the 
rest  of  the  basin. 

Most  water-courses,  however  winding  their  course  may  have  been, 
straighten  as  they  approach  the  sea,  and  descend  toward  the  shore  by  the 
shortest  line  possible,  so  as  to  form  a  right  angle  with  the  coast.  This 
tendency  may  be  partially  explained  by  the  fact  that  the  steepest  slope 
of  the  ground  is  generally  inclined  in  this  direction ;  but  another  cause, 
also,  is  the  alternate  action  of  the  tide-wave,  which  takes  place  perpendic- 
ularly to  the  shore,  the  to-and-fro  motion  of  which  ultimately  governs  that 
of  the  river. 

Added  to  this,  a  large  number  of  rivers,  when  they  reach  the  maritime 
portion  of  their  course,  spread  out  their  banks  very  widely  so  as  to  form 
'real  gulfs,  in  which  it  would  be  impossible  to  trace  out  the  precise  limit 
which  marks  the  river-mouth.  When  these  bays  are  not  original  indenta- 
tions of  the  coast,  they  owe  their  existence  to  the  combined  action  of  the 
river  and  the  sea,  which  gradually  cuts  away  the  banks,  and  ultimately 
deposits  them  on  some  distant  shore.  Thus  fluviatile  estuaries  are  gen- 
erally found  on  those  parts  of  the  coast  which  are  directly  exposed  to  the 
force  of  the  tides  and  storms.  Estuaries  are  very  numerous  on  the  coasts 
of  the  open  sea  where  the  tide  rises  to  a  great  height,  but  they  are  com- 
paratively less  frequent  in  land-locked  seas,  which  preserve  an  almost  un- 
altered level,  such  as  the  Mediterranean,  the  Baltic,  and  the  Caribbean 
Sea.  Nevertheless,  the  shores  of  several  inland  seas — among  others,  the 
Euxine,  so  formidable  for  its  winds — present  river-estuaries  similar  to  those 
on  the  oceanic  coasts;  the  most  remarkable  are  the  Umans  of  the  Dniester 
and  the  Bug. 

Almost  all  the  rivers  of  Western  Europe  spread  out  into  estuaries  in  the 
lower  portion  of  their  course.  There  are  some  among  the  number,  as  the 
Thames,  the  Severn,  and  other  rivers  of  Great  Britain,  which  are  streams 
of  no  great  importance  above  the  gulfs  at  their  outlets,  and  owe  all  their 
consequence  to  the  powerful  tide-waves  of  the  Atlantic.  In  France,  the 
Seine,  the  Loire,  and  the  two*  combined  rivers  of  the  Garonne  and  the  Dor- 
dogne,  water  basins  which  are  better  proportioned  in  their  area  to  the  di- 
mensions of  their  estuaries  ;  nevertheless,  the  quantity  of  fresh  water  sent 
down  into  these  advanced  bays  of  the  ocean  forms  but  a  very  small  por- 
tion of  the  liquid  mass  which  they  contain.  In  the  Gironde,  which  may 
be  taken  as  a  type  of  a  marine  estuary,  the  salt  water  generally  ascends 
as  far  as  Pauillac,  31  miles  from  the  outlet ;  any  one  sailing  on  the  river 
may  readily  notice  the  shifting  line  where  the  various  liquid  masses,  some 


ESTUARIES.  341 

green  and  transparent,  and  others  yellow  and  muddy,  mingle  with  one  an- 
other in  long  eddies. 

At  a  point  more  than  10  miles  from  the  sea-coast,  the  saltness  of  the 
Gironde  is  scarcely  diminished  by  the  admixture  of  fresh  water.  At  one 
time,  the  low  ground  by  the  river-side  was  intersected  by  salt  marshes, 
and  the  creek  of  Mechers,  on  the  north  bank,  has  been  utilized  for  some 
years  in  the  cultivation  of  oysters.  The  depth  of  the  estuary  is  also  very 
considerable.  At  Mechers,  the  Gironde,  which  at  that  place  is  7^  miles 
wide,  is  from  50  to  100  feet  deep  even  at  low  tide.  At  the  outlet  properly 
so  called,  the  estuary  contracts,  and  is  only  3^  miles  wide ;  but  in  mid- 
channel,  the  sounding-line  finds  no  bottom  at  100  feet.  This  enormous 
basin  does  not  look  like  a  river.  If  a  spectator  contemplates  it,  not  from 
the  point  of  a  headland,  but  merely  from  the  edge  of  the  shore,  at  St. 
George  or  Royan,  he  can  not  distinguish  the  whole  extent  of  the  opposite 
bank ;  all  that  is  visible  is  a  few  clumps  of  pines,  separated  by  the  white 
line  of  the  distant  water,  and  these  isolated  clumps  seem  to  form  an  archi- 
pelago ;  the  Gironde  appears  like  a  sea  dotted  over  with  isles  and  islets. 
The  color  and  the  appearance  of  the  water  are  continually  changing ;  it  is 
as  if  several  rivers,  crossing  one  another  in  every  direction,  were  flowing 
in  one  and  the  same  bed.  Sand-banks  which  show  their  white  masses  in- 
distinctly under  the  -green  waves,  the  marine  cuiTcnts  which  meet  and 
mingle  with  the  turbid  water  of  the  ebbing  tide,  the  gusts  of  wind  which 
raise  on  the  estuary  a  perfect  net- work  of  winding  ripples,  the  long  trains 
of  foam  which  incessantly  shift  their  place ;  lastly,  the  submarine  counter- 
currents  which  flow  up  to  the  surface  and  there  spread  out  in  sheets  per- 
fectly smooth — all  these  ever-changing  phenomena  are  always  modifying 
the  magnificent  spectacle  aflbrded  by  the  Bay  of  Gironde. 

But  what,  after  all*,  is  this  beautiful  estuary  of  the  French  coast  when 
compared  with  the  grand  outlets  of  some  of  the  American  rivers,  such  as 
the  St.  Lawrence,  the  current  of  the  Amazons,  and  the  Rio  de  la  Plata? 
This  last  estuary,  into  which  pour  the  gigantic  Parana  and  Uruguay,  more 
than  six  miles  in  width,  is  at  the  outlet  no  less  than  155  miles  across,  and 
occupies  a  space  of  more  than  15,400  square  miles.  Within  a  recent  geo- 
logical period  it  stretched  over  a  still  wider  area.  At  that  time  the  Pa- 
rana had  not  filled  up  with  its  alluvium  all  the  higher  portion  of  the  estu- 
ary, and  probably,  also,  the  surface  of  the  pampas  was  covered  by  the  sea- 
water.  Even  in  the  present  day,  the  now  diminished  gulf  is  nothing  less 
than  a  real  sea.  Its  bed,  which  prolongs  in  a  gentle  slope  the  surface  of 
the  Argentine  plain,  is  hollowed  out  66  to  100  feet  below  the  level  of  the 
ocean.  Currents  and  counter-currents,  like  those  in  the  open  sea,  traverse 
the  gulf  in  every  direction.  Furious  winds,  which  seem  to  upheave  the 
whole  liquid  mass,  give  rise  to  tempests  which  are  more  dreaded  than 
those  of  the  ocean,  on  account  of  the  sand-banks  and  rocks  which  hem  in 
the  channels.  The  highest  floods  of  the  Uruguay  and  the  Parana  have  no 
perceptible  influence  on  the  level  of  the  Rio  de  la  Plata,  and  seem  lost  like 
rivulets  in  the  enormous  estuary. 


342 


THE  EARTH. 


Although  the  winds  and  tide  have  such  an  effect  in  increasing  the 
mouths  of  rivers,  into  which  the  waves  enter  in  a  direct  line,  their  mode 
of  action  is  very  different  when  they  are  diffused  along  a  sandy  shore, 
which  they  meet  at  a  very  acute  angle.  In  this  case,  the  waves  from  the 
open  sea,  being  driven  obliquely  against  the  coast,  wash  away  from  it 
large  quantities  of  debris,  which  they  deposit,  in  front  of  the  mouth  of  the 
adjacent  river.  Under  the  enormous  pressure  of  the  ocean,  the  current  of 
the  river  bends  and  gradually  doubles  round  in  the  same  direction  as  the 
marine  current,  allowing  a  tongue  of  sand  to  form  across  its  former  bed. 
In  the  course  of  time,  a  narrow  peninsula,  having  a  sea-shore  on  one  side 
and  a  river-bank  on  the  other,  divides  the  fresh  water  from  the  salt  water 
for  a  distance  of  several  miles,  sometimes  breaking  up  into  islands,  accord- 
ing to  the  various  changes  of  the  atmosphere,  the  current,  and  the  tides. 
Thus,  on  the  coast  of  New  Granada,  extending  from  the  Cape  de  la  Vela 
to  the  foot  of  the  snow-clad  mountains  of  Santa  Marta,  all  the  river  outlets 
are  pushed  toward  the  west  by  the  current  which  runs  along  the  shore  to- 


Fig.  133.  Belts  of  the  Senegal. 


MOUTH  OF  THE  SENEGAL.— L ANDES.  343 

ward  the  Gulf  of  Darien  ;  mere  embankments,  ornamented  here  and  there 
with  green  vine-branches,  and  the  violet  corollas  of  a  kind  of  bindweed, 
protect  the  still  waters  against  the  onset  of  the  breakers. 

The  River  Senegal  exhibits  one  of  the  most  remarkable  examples  of 
these  belts,  formed  along  the  shore  by  the  marine  currents,  and  running 
across  the  outlet  of  a  river.  For  a  distance  of  more  than  180  raUes,  the 
great  water-course  follows  a  direction  perpendicular  to  the  coast.  In  this 
way  it  reaches  a  point  15  miles  from  the  sea,  at  which  its  course  is  arrest- 
ed by  a  chain  of  dunes,  and  it  is  compelled  to  find  an  outlet  through  some 
other  part  of  the  sea-shore.  At  one  time  the  river,  or  at  least  one  of  its 
branches,  continued  in  its  direct  path  to  the  ocean,  and  on  the  spot  where 
its  former  bed  may  still  be  traced  there  is  a  narrow  marshy  flow,  known 
under  the  name  of  the  Marigot  of  N'diadier.  Being  thus  driven  in  a 
southwest  direction,  the  Senegal  is  compelled  to  approach  the  sea  oblique- 
ly. Above  St.  Louis  the  river  is  separated  from  the  line  of  breakers  by 
nothing  but  the  narrow  bank  of  the  Guet-N'dar,  on  which  the  blacks  have 
built  i\\Q\r  faubourg.  Farther  down  the  coast,  the  embankment  of  sand 
thrown  up  by  the  marine  current  running  from  the  north  continues  for  a 
considerable  length,  altering  its  position  every  year,  owing  to  the  double 
action  of  the  river-floods  and  the  sea-waves.  At  the  present  time  the 
mouth  of  the  Senegal  opens  2^  miles  south  of  St.  Louis,  and  is  ascending 
slowly  toward  the  town.  In  1849  it  was  9  miles  farther  to  the  south, 
but  in  1825  it  was  near  Gandiole,  a  little  farther  up  the  stream.  This 
sandy  rampart,  which  extends  its  graceful  curve  from  north  to  south  for 
more  than  24  miles,  is  cut  through  by  the  current  of  the  river,  sometimes 
at  one  spot  and  sometimes  at  another,  but  it  never  fails  to  form  again, 
owing  to  the  action  of  the  sea-waves.  Lentil  the  operations  of  man  have 
fixed  the  place  of  the  mouth  of  the  Senegal,  it  will  continue  to  shift  its  po- 
sition along  the  sandy  dike. 

In  a  similar  way,  all  the  various  streams  which  empty  into  the  sea  along 
the  low  coasts  of  the  French  Landes  bend  round  toward  the  south  as  soon 
as  they  reach  a  point  at  a  short  distance  from  the  sea-shore.  '  Tliere  is,  in 
fact,  a  current  produced  by  the  swell  which  runs  parallel  to  the  shore  of 
the  Landes.,  a  matter  which  is  easily  proved  by  noticing  the  drifting  of 
any  floating  substance,  or  the  bearing  of  shipwrecked  vessels,  which  al- 
ways point  their  sterns  to  the  south.  This  current  pushes  before  it  mass- 
es of  sand,  which  are  mixed  with  the  breakers,  and  thrown  up  upon  the 
beach.  The  sandy  points,  which  are  constantly  augmented  by  the  addi- 
tions brought  by  the  waves,  are  thus  elongated  toward  the  south,  and 
would  ultimately  reach  the  bases  of  the  Pyrenean  promontories  if  it  were 
not  for  the  tendency  of  the  streams  to  rise,  so  as  to  increase  their  slopes, 
and  thus  to  press  with  increasing  weight  on  the  sands  which  obstruct 
them.  Formerly  the  waste  channels,  or  "  courants^^''  of  the  Lakes  of  Sous- 
tons  and  St.  Julian  flowed  parallel  to  the  sea  for  a  length  of  several  miles 
above  their  outlet,  and  fears  were  entertained  that,  in  consequence  of  the 
lengthening  of  these  streams,  and  the  rise  in  their  level,  the  lakes  above 


344  ^^^  EARTH. 

would  spread  over  the  surrounding  country.  In  order  to  avert  this  disas- 
ter, the  inhabitants  undertook  to  rectify  the  course  of  the  waste  channels, 
and  thus  to  lower  the  level  of  the  lacustral  waters.  This  plan  succeeded 
perfectly  as  regards  the  Soustons  Lake.  Its  level  was  sunk  10  feet,  to  the 
great  advantage,  of  the  village  near,  which  was  enriched  with  a  tract  of 
fertile  %lluvium.  The  Lake  of  St.  Julian  was  likewise  lowered  several  feet 
by  the  alterations  made  in  the  "  couranf''  of  Contis ;  but  the  engineers 
met  with  considerable  difficulty  in  mastering  this  water-course,  and  in  pre- 
venting it  from  flowing  in  a  southerly  direction  parallel  with  the  coast. 
They  were  several  times  compelled  to  lengthen  the  barrier  which  forced 
it  to  flow  in  a  straight  line  down  to  the  sea.  As  regards  the  more  im- 
portant stream  of  Mimizan,  which  serves  as  a  waste-channel  for  several 
considerable  lakes,  an  attempt  was  often  made  to  dig  out  for  it  a  regular 
bed  in  the  direction  of  the  coast,  and  to  retain  the  flow  of  water  in  it ;  but 
the  river  would  not  be  subdued,  and,  throwing  down  the  barrier  of  piles 
and  fagots  which  was  opposed  to  it^  continued  to  run  toward  the  south 
and  southeast.  Miles  of  basket-work,  dikes,  which  were  set  up  to  guide 
its  waters,  now  lie  buried  under  the  dunes. 

During  the  course  of  the  Middle  Ages,  and  probably  also  in  the  previous 
historical  era,  the  Lower  Adour,  which  is  now  perpendicular  to  the  coast, 
extended  in  a  line  parallel  to  the  chain  of  dunes  and  the  sea-shore  for  a 
length  of  about  12^  miles.  The  river  then  fell  into  the  sea  at  a  short  dis- 
tance from  the  spot  where  the  town  of  Cape  Breton  now  stands.  Toward 
the  end  of  the  fourteenth  century  a  violent  tempest  obstructed  this  outlet, 
and  the  Adour,  thrown  back  farther  to  the  north,  found  no  place  of  issue 
nearer  than  a  point  22  miles  from  Bayonne;  a  village  called  Vieux  Boucau 
(old  mouth)  marks  the  banks  of  the  former  river.  At  first  sight  it  seems 
as  if  this  ancient  course  of  the  Adour  is  to  be  explained  in  a  similar  way 
as  the  curves  described  toward  the  south  by  the  streams  of  the  Landes; 
but,  if  this  were  the  case,  the  current  of  the  sea-swell  in  this  part  of  the 
Gulf  of  Gascony  ought  to  tend  in  a  northerly  direction.  Now  the  action 
of  the  waves  points,  on  the  contrary,  from  north  to  south,  as  far  as  the 
mouth  of  the  Bidassoa,  and  consequently  the  sandy  points  are  lengthened 
with  a  southerly  bearing.  The  belt  of  banks  across  the  course  of  the 
Adour  was  turned  toward  the  north  ;  it  is  therefore  necessary  to  look  for 
the  cause  of  this  in  the  existence  of  a  chain  of  dunes  solidly  based  on  the 
nearest  Pyrenean  rocks,  which  presented  an  insuperable  barrier  to  the 
river  on  the  western  side.  In  1578  this  chain  was  broken  through  at  a 
point  three  miles  and  three  quarters  below  Bayonne,  by  means  of  a  trench 
cut  by  Louis  de  Foix,  the  engineer,  and  still  more  by  a  formidable  flood, 
which  threatened  to  carry  away  the  city.  Since  this  date,  the  mouth  of 
the  Adour,  yielding  to  the  coast-current,  constantly  tends  to  bend  round 
toward  the  south,  and  on  this  side  the  piers  formed  to  maintain  the  river 
are  carried  the  farthest.  At  the  end  of  the  seventeenth  century — at  a 
date  when  these  latter  works  had  not  been  commenced — the  river,  bend- 
ing gradually  toward  the  south,  emptied  itself  into  the  sea  at  the  foot  of 


CHANGES  IN  RIVER-MOVTHS. 


345 


Fig.  134.  Old  Conrse  of  the  Adour. 


the  rocks  of  Chambre  d'Amour,  about  two  miles  from  Boucau  Neuf  (new 
mouth).  If  the  river  had  not  been  repelled  on  the  right  by  the  dikes  con- 
structed by  Louis  de  Foix,  it  is  very  possible  that  it  would  again  have 
turned  toward  the  north.* 

One  of  the  most  wonderful  phenomena  on  the  face  of  the  earth  is  the 
formation  of  those  long  banks  of  alluvium  which  affect  a  considerable 
number  of  streams,  and,  for  a  distance  of  hundreds  of  miles,  protect  a 
multitude  of  river  outlets  against  the  waves  of  the  sea.  A  magnificent 
example  of  this  formation  exists  on  the  coasts  of  Virginia  and  North  Car- 
olina. The  rivers  there,  which  flow  on  the  surface  of  the  ground,  counter- 
poising the  pressure  of  the  ocean  in  the  same  way  as  the  subterranean 
waters  of  Yucatan,f  have  formed  out  at  sea  an  immense  breakwater.  This 
sandy  dike — which  is  not  less  than  186  miles  in  length,  bends  round  the 
continent  in  gracefully-winding  curves,  and  incloses  within  its  limits  per- 
fect seas,  with  their  bays,  archipelagoes,  and  currents;  behind  this,  the 
Tar,  the  Alligator,  the  Neuse,  and  several  rivers *run  into  the  sea.  An  idea 
may  be  formed  of  the  poculiarities  presented  by  these  long  banks,  com- 

*  Vionnois,  Annnles  ties  Fonts  et  Chaussies,  vol.  xvi.  t  Vide  above,  p.  248,  249. 


;^46  T^^  EARTH. 

iiion  to  several  rivers,  by  comparing  this  dike  with  the  altogether  regu- 
larly formed  littoral  bank  which  lies  in  front  of  the  River  Cape  Fear,  im- 
mediately to  the  south. 

A  third  arrangement  of  the  mouths  of  rivers  is  that  which  the  ancient 
Greeks  designated  under  the  name  o^  delta  (A),  on  account  of  the  triangu- 
lar form  so  often  assumed  by  the  alluvial  plain  embraced  between  the 
branches  of  a  river.  This  plain,  which  projects  beyond  the  regular  line 
of  the  coast,  is  nothing  but  a  former  estuary,  which  has  gradually  been 
tilled  up  with  mud  and  sediment  of  every  kind.  This  alluvial  plain  can 
not  be  formed  to  any  great  extent  in  places  where  the  swell,  the  currents, 
and  the  tides  are  constantly  disturbing  the  outlets  of  the  rivers.  It  is 
necessary  that  the  stream  should  be  subject  to  Qonditions  somewhat  simi- 
lar to  those  existing  in  still  lakes,  where  deltas  form  without  the  least  ob- 
stacle. These  conditions  are  found  in  almost  inland  seas,  with  a  scarcely 
perceptible  current — such  as  the  Mediterranean  and  the  Baltic — which  al- 
low river-mouths  to  gradually  fill  up  with  mud.  The  alluvium  which  is 
brought  down  by  the  river  is  certainly  soft,  and  has  but  little  solidity ; 
it  is  often  roughly  handled  by  the  water  at  flood-times,  and  fails  in  pre- 
venting the  liquid  mass  from  forming  forks,  or  even  from  dividing  into 
numerous  branches.  But  the  sea,  which  assails  these  deposits,  being  con- 
stantly at  about  the  same  level,  ultimately  has  the  effect  of  consolidating 
them'  by  dashing  against  them  with  its  waves.  On  the  contrary,  when  a 
river  falls  into  a  sea  where  the  tides  rise  to  a  great  height,  and  where  the 
coast  is  alternately  traversed  by  the  rapid  currents  of  the  ebb  and  flow, 
no  time  is  left  for  the  deposit  of  the  river  alluvium.  This  matter  is  first 
pushed  back  into  the  river  by  the  flow  of  the  tide,  and  then,  being  seized 
by  the  ebb,  is  carried  out  to  great  depths  in  the  open  sea.  In  this  contest 
between  the  river  and  the  ocean,  the  latter  gets  the  advantage  on  account 
of  the  enormous  mass  of  its  waves,  which,  by  their  fluctuating  movement 
of  rising  and  falling,  are  incessantly  scouring  out  the  estuary  through 
which  the  fresh  water  flows. 

Among  those  rivers  the  deltas  of  which  are  incessantly  gaining  on  the 
sea,  we  may  mention,  as  belonging  to  the  first  class  in  this  respect,  the 
great  afiluents  of  the  Mediterranean,  the  Danube,  the  Nile,  the  Po,  and  the 
Rhone ;  also,  in  the  Caspian,  the  Terek,  the  Kouban,  and  the  Volga.  Other 
rivers  possessing  deltas  fall  into  the  sea  at  the  extremity  of  some  gulf 
well  sheltered  by  a  barrier  of  isles,  and  visited  only  by  scanty  tides.  Of 
this  kind  are  the  Hoang-ho,  the  Yang-tse-kiang,  and  other  water-courses, 
the  alluvial  shores  of  which  continue  to  project  more  and  more  into  the 
^hallow  Chinese  Sea  and  the  Gulf  Pe-tchi-li.  The  delta  of  the  Mississippi, 
which  may  serve  as  a  type  to  all  other  formations  of  the  same  nature, 
pushes  its  way  into  an  almost  closed  gulf,  where  the  height  of  the  regular 
tide  never  exceeds  three  feet.  The  only  instance  which  can  be  mentioned 
of  a  great  river  delta  existing  at  the  extremity  of  a  gulf  widely  open  to 
the  ocean  is  that  of  the  Ganges  and  the  Brahmapootra.  But  it  must  not 
be  forgotten  that  at  the  outlets  of  these  rivers,  the  tide,  fluctuating  be- 


DELTAS.  34,7 

tween  1  foot  and  16^  feet,  never  exceeds,  on  the  average,  10  feet  in  height;* 
added  to  this,  the  delta,  instead  of  pushing  its  way  far  into  the  sea,  pre- 
sents a  flattened  shape,  and  extends  its  low  shores  from  east  to  west,  giv- 
ing a  width  of  at  least  186  miles.  There  is  no  doubt  that  in  a  more  pro- 
tracted sea,  tlie  delta  of  these  two  combined  rivers  of  Hindostan,  which 
bring  down  in  their  turbid  waters  so  large  a  quantity  of  alluvium,  would 
have  thrown  out  a  long  promontory  of  delta  exhibiting  very  diflerent  pro- 
portions. 

In  a  cursory  and  rapid  examination  of  a  map,  it  would,  however,  be 
easy,  to  fall  into  error  as  to  the  real  character  of  certain  river-outlets,  and 
to  look  upon  them  as  actual  deltas,  thrown  out  by  the  action  of  the  river 
itself,  instead  of  collections  of  soil  deposited  under  the  shelter  of  isles  of 
marine  formation.  Thus  Holland,  which  is  placed  at  the  angle  of  the 
continent  of  Europe,  appears  at  first  sight  to  be  the  combined  delta  of 
the  Scheldt,  the  Meuse,  and  the  Rhine ;  but  the  outer  shore  is,  in  fact,  an 
ancient  coast  cut  through  by  the  waves  of  the  ocean,  and  is  composed  of 
a  vast  semicircle  of  dunes,  stretching  from  the  mouths  of  the  Scheldt  to 
those  of  the  Ems  and  the  Weser.  Far  from  having  gone  beyond  this 
original  coast-belt,  the  greater  part  of  the  Dutch  rivers  have  formed  estu- 
aries, and  the  wide  sheets  of  the  Bies-bosch,  the  Zuyder  Zee,  and  the  Dol- 
lart  constitute  unquestionable  testimony  of* the  invasion  of  the  sea-water. 
The  alluvial  tracts  of  Holland  do  not,  therefore,  present  the  character  of 
a  delta  properly  so  called. 

Deltas  are  not  formed  solely  on  the  lower  portion  of  a  river's  course ; 
they  also  exist  at  all  the  points  of  the  river  where  former  lacustrine  basins 
have  been  filled  up  by  one  or  more  several  affluents.  At  these  spots,  the 
))rincipal  water-course  and  its  tributaries  divide  into  several  branches, 
radiating  in  a  fan-like  shape  across  the  alluvial  plain;  sometimes  they 
even  cross  one  another  so  as  to  form  a  complete  net-work.  About  the 
middle  of  its  course,  the  Mississippi  receives  two  considerable  affluents 
from  the  west,  the  Arkansas  and  the  White  River.  The  principal  river 
and  its  two  tributaries  are  united  by  a  net-work  of  innumerable  bayous,f 
which  at  every  inundation  change  their  course  and  their  depth,  falling 
alternately  into  one  or  the  other  of  the  three  currents,  according  to  the 
respective  height  of  their  waters.  When  the  Mississippi  is  very  high,  it 
•  lisgorges  its  surplus  water  into  the  system  of  bayous^  and  the  latter 
empty  into  the  Arkansas  and  the  White  River.  During  the  low-water 
season,  on  the  contrary,  when  the  water  poured  by  the  Mississippi  into 
the  mai-shes  above  has  had  sufficient  time  to  flow  from  lagoon  to  lagoon 
down  to  the  White  River,  the  latter  feeds  the  net-work  of  bayous  Avhich 
connects  it  with  the  Mississippi  and  the  Arkansas.  When  the  latter  river 
is  swollen  more  than  usual  after  heavy  rains  in  the  Western  prairies,  then 
the  pressure  of  its  water  drives  back  that  of  the  Mississippi,  and  for  a 

•  Be&rdmore,  Manual  of  II>fdrolo<jtf. 

+  Derived  from  the  French  word  Ixiie.  The  Spaniards  of  La  I'hua  give  the  name  of  bahia 
to  natural  channels  of  the  same  description. 


348 


THE  EARTH. 


time  the  Arkansas  takes  possession  of  the  common  delta.  On  the  banks 
of  the  Amazon  River  all  these  phenomena  take  place  with  much  more 
grandeur ;  at  the  mouth  of  the  Japura  especially,  the  principal  current 
forms  with  its  affluent  an  inextricable  net-work  of  false  rivers,  which  seem 
to  flow  indifierently  in  any  direction,  and,  for  a  space  of  several  thousand 
square  miles,  direct  their  surplus  waters  from  marsh  to  marsh  through  the 
virgin  forests.  This  system  offuros,  as  they  are  called  in  South  America, 
resembles  those  congestions  in  the  human  body  when  the  too  great  abun- 
dance of  blood  gives  rise  to  a  system  of  false  arteries  and  veins. 


J 


CHANNELS  OF  THE  MISSliiSIFrL  34.9 


CHAPTER  LIIL 


)) 


THE   CHANNELS    OP   THE    MISSISSIPPI. "WORKING    RIVERS.   — SHIFTING    OF 

THE    POINT    OF   BIFURCATION. — RAISING    OP   THE    RIVER-BED   ABOVE    THE 
DELTA. — ALTERATION   IN   THE   SITUATION    OF   MOUTHS    OF   RIVERS. 

In  a  geographical  point  of  view,  it  is  important  not  to  confound  appa- 
rent deltas  with  the  real  deltas  of  alluvial  earth.  Thus  the  basin  of  the 
Mississippi,  in  which  there  is  opportunity  for  studying  so  many  other  hy- 
drological  phenomena,  exhibits  several  instances  of  emissaries  which  must 
not  be  looked  upon  as  branches  of  the  delta.  The  Atchafalaya,  in  fact,  is 
not  a  branch  of  the  Mississippi,  as  it  is  not  fed  by  the  latter ;  it  is,  on  the 
contrary,  a  continuation  of  the  lied  River,  which  sends  down  to  the  Atcha- 
falaya a  portion  of  its  water  directly,  and  another  portion  indirectly,  by 
using  for  nearly  a  mile  the  bed  of  the  Mississippi  itself  The  Plaquemine 
and  Lafourche  bayous,  which,  during  floods,  receive  a  small  portion  of  the 
water  of  the  Mississippi,  are  not  regular  fluviatile  beds,  like  the  branches 
of  the  Rhone,  the  Nile,  and  the  Po ;  they  are  mere  channels  communica- 
ting between  the  inland  lakes  and  marshes,  and  have  become  united  to  the 
Mississippi  by  an  erosion  of  the  banks  of  the  river.  It  is,  indeed,  owing 
to  the  labor  of  man — that  is,  to  the  side  embankments  and  the  drainage 
of  the  marshes  near  it — that  the  Lafourche  bayou  has  assumed  the  aspect 
of  a  river  for  so  large  a  portion  of  its  coui-se,  and  now  no  longer  disap- 
pear, as  it  once  did,  in  a  labyrinth  of  pools  and  marshes.  The  Manchac, 
or  Iberville  iayoi^,  which  used  to  reach  the  sea. through  the  Amite  River 
and  the  Lake  Maurepas,  is  now  completely  obliterated  by  the  alluvium 
and  masses  of  entangled  trees ;  but  it  has  always  been  a  mere  flow  of  no 
great  importance.*  Thus  the  delta  proper  only  commences  at  the  "  Head 
of  the  Passes,"  and  this  sheath-like  bed,  through  which  the  Mississippi  rolls 
between  two  narrow  banks  of  alluvium,  one  side  of  which  is  sea-sliore  and 
the  other  river-bank,  is,  geologically  speaking,  the  sole  bed  of  the  river. 
Projecting  from  the  continent  like  an  arm,  it  pushes  out  for  62  miles  into 
the  sea,  and  spreads  over  the  water  the  branches  of  its  delta,  like  the  fin- 
gers of  a  gigantic  hand.  A  Hindoo  might  well  compare  the  extension  of 
the  mouths  of  the  river  to  an  immense  flower  opening  over  the  ocean  its 
serrated  corolla. 

These  narrow  embankments  of  mud,  brought  down  into  the  open  sea  by 
the  fresh  water,  present  a  striking  spectacle.  In  several  places  these 
banks  are  only  a  few  yards  thick,  and  during  storms  the  waves  of  the  sea 
curl  over  the  narrow  belt  of  shore  and  mingle  with  the  river.  The  soil 
of  the  banks  becomes  perfectly  spongy ;  it  is  not  firm  enough  to  allow 
*  Hurophrevs  and  Abbot,  Report  on  the  Mississippi  River,  1861. 


350 


THE  EARTH. 


even  willows  to  take  root,  and  the  only  vegetation  is  a  species  of  tall  reed 
{Miegea  niacrosperma),  the  fibrous  roots  of  which  give  a  little  cohesion  to 
the  ooze,  and  prevent  its  being  dissolved  and  washed  away  by  the  succes- 
sion of  tides.     Farther  down  the  reeds  disappear,  and  the  banks  of  mud 


AM'! 

wrt' 


^sfJPP^f? 


Fig.  135.  Months  of  the  Missibsippi. 

form,  are  washed  away,  and  form  again,  wandering,  so  to  speak,  between 
the  river  and  tlie  sea,  at  the  will  of  the  winds  and  tide.  On  the  left  bank 
of  the  southwest  passage,  which  is  used  for  the  largest  ships,  the  plank- 
built  huts  of  a  small  pilots'  village  have  been  fixed  as  delicately  as  possi- 
ble. These  constructions  are  so  light,  and  the  ground  that  carries  them  is 
so  unstable,  that  they  have  been  compelled  to  anchor  them  like  ships,  fear- 
ing that  a  hurricane  might  blow  them  away ;  still,  the  force  of  the  wind 
often  makes  them  drag  on  their  anchors.  Below,  the  banks  of  the  Missis- 
sippi are  reduced  to  a  mere  belt  of  reddish  mud,  cut  through  at  intervals 
by  wide  cross  streams ;  still  farther  down  even  this  narrow  belt  comes  to 
an  end,  and  the  banks  of  the  river  are  indicated  by  nothing  but  islets, 
which  rise  at  increasing  distances  from  one  another,  like  the  crests  of  sub- 
marine dunes.  Soon  the  summits  of  these  islets  assume  the  appearance 
of  a  thin  yellow  palm  floating  on  the  surface  of  the  water.  Then  all  is 
mud :  the  land  is  so  inundated  with  water  that  it  resembles  the  sea,  and 


LA  YERS  OF  WA  TER 


351 


tlie  sea  is  so  saturated  with  mud  that  it  resembles  the  land.  Finally,  all 
trace  of  the  banks  disappears,  and  the  thick  water  spreads  freely  over  the 
ocean.  After  getting  clear  of  the  bar,  the  sheet  of  water  which  was  the 
Mississippi  preserves,  during  floods,  the  yellowish  color  by  which  it  can 
be  distinguished  for  about  twenty  miles,  but  it  loses  in  depth  all  that  it 
gains  in  extent,  and,  gradually  depositing  the  earthy  matters  which  it 
holds  in  suspension,  becomes  ultimately  perfectly  mingled  with  the  sea. 


^v-<:'t^<^ 


Fig.  130.  Cbanoel  of  Lontre. 


In  calm  weather,  the  union  of  the  fresh  and  salt  water  presents  an  in- 
teresting spectacle,  affording  some  similarity  to  the  meeting  of  the  tide 
and  the  river-current  in  an  estuary.  Gliding  in  layers  of  incr<?asing  thin- 
ness over  the  weightier  masses  of  the  ocean,  the  muddy  water,  on  escaping 
from  the  mouths  of  the  delta,  swims  like  oil  on  the  surface  of  the  waves, 
and  the  sailors  are  able  to  collect  it  without  difliculty  by  skimming  the 
surface.  Ships,  as  they  pass,  break  through  this  light  yellowish  sheet,  and 
leave  behind  them  a  long  track  formed  by  the  blue  and  transparent  water 
of  the  sea.  A  contrast  of  the  same  nature  is  produced  at  the  spot  where 
the  Gulf  Stream  causes  the  belt  of  the  water  of  the  Mississippi  to  swerve 
to  the  east;  one  might  fancy  that  a  straight  line  traced  out  by  a  ruler 


352 


THE  EARTH. 


separated  the  two  diversely-colored  waters  as  far  as  the  horizon.  Finally, 
the  sheet  of  fresh  water,  becoming  very  thin,  is  broken  up  into  little  tur- 
bid islets,  surrounded  with  salt  water.  They  are  often  full  of  vegetable 
debris — they  are  then  edged  with  breakers  in  miniature,  which  give  them 
a  border  of  foam.*  The  sounding-line  let  down  to  the  bottom  of  the  sea 
off  the  mouth  of  the  river  finds  the  mud  of  the  Mississippi  as  far  as  the 
coral  banks  of  the  Florida  coast.  The  accompanying  plates  show  the  dif- 
ference in  the  depth  of  the  sea  between  the  axis  of  the  Mississippi  and 
those  portions  of  the  gulf  which  are  situated  immediately  to  the  south. 


137.  Depths  of  the  Gulf  of  Mexico  iu  the  Axis  of  the  Mississippi  Current. 


The  fluviatile  tracts  of  alluvium  which  are  constantly  forming  before 
our"  eyes  may  be  classed  among  the  most  important  geological  phenomena 
in  the  history  of  the  globe.  Owing  to  the  quantity  of  mud  which  the 
masses  of  running  water  bring  down  to  their  outlets,  the  shore-line  is  in- 
cessantly changing,  and  continents  are  increased  in  area.  Carl  Ritter  has 
given  the  name  of  "  working  rivers"  {fleuves  travailleurs)  to  those  water- 
courses which  deposit  a  large  quantity  of  alluvium  in  deltas,  and  push  their 
shores  farther  and  farther  into  the  midst  of  the  sea.  Every  river,  indeed, 
takes  its  share  in  this  labor,  but  in  great  deltas  the  earth  quite  visibly 
encroaches  upon  the  ocean.  At  the  mouths  of  several  rivers  the  lifetime 
of  a  man  would  be  a  period  long  enough  for  the  salt  bay  to  be  converted 
into  a  plain,  and  the  floating  sea- weed  beds  to  become  a  magnificent  forest. 


Fig.  138.  Depths  of  the  Galf  of  Mexico  south  of  the  Missisaippi  Current. 

The  deltas  themselves,  the  vast  plains  which,  as  Herodotus  says,  are  the 
"gifts  of  rivers,"  bear  witness  to  the  geological  importance  of  running  wa- 
ters in  the  formation  of  continents.  But  the  investigations  which  have 
been  made  up  to  the  present  day  enable  us  to  estimate  the  progressive 
course  of  these  alluvial  formations  in  but  a  small  number  of  rivers.  In 
fact,  the  problem  which  has  to  be  resolved  is  a  very  complex  one.  In  the 
first  place,  it  would  be  indispensable  to  prepare  at  intervals  exact  charts 
*  Kohl,  Zeitschri/t  fur  allgemeine  Erdkunde,  September,  1 804. 


DELTA  OF  THE  GANGES 


PI,  XVII 


O  F 


.;^ 


B^    K    O  A 


**    East  of  Pans 


OtMwr    by     A.  Vuilleinin    after    Xassm. 

-     ■  HARPEn.  isc  hROT^'T'^S.  NEW  Yv/.^ 


5i^<l  by  EAari 


ALLUVIUM  OF  RIVERS.  353 

of  the  sea-coast  an^  the  depths  of  the  sea  in  the  vicinity;  next,  it  would 
be  requisite  to  strictly  apportion  the  quantity  of  sediment  brought  down 
in  each  season  of  the  year  by  the  water  of  the  river,  and  to  ascertain  the 
amount  of  alluvium  which  is  lost  along  the  coast.  Lastly,  in  the  beds  of 
the  delta  itself,  it  would  be  necessary  to  distinguish  between  the  debris 
washed  away  from  the  adjacent  coast  and  the  matter  which  is  brought 
down  by  the  river ;  for  when  a  muddy  point  is  formed,  the  currents  along 
the  shore  always  drive  upon  it  a  constantly  increasing  bank  of  sand. 
Some  day,  doubtless,  more  exact  observations  will  enable  us  to  trace  out 
the  journey  of  the  alluvium  down  the  river  that  carries  it  along;  we  shall 
ascertain  the  average  time  that  elapses  before  the  rock  rolled  down  by  the 
torrent  is  broken  up  into  pebbles,  and  then  in  succession  reduced  to  grav- 
el, sand,  and  impalpable  mud ;  we  shall  learn  the  number  of  resting-places 
that  the  debris  avail  themselves  of  in  bend  after  bend  from  the  river's 
source  to  the  sea.  Perhaps,  even  by  the  mere  observation  of  the  alluvial 
layers,  we  shall  be  able  to  discover  the  age  of  the  bed,  as  we  ascertain  the 
age  of  a  tree  by  its  concentric  rings.  We  must,  however,  confess  that  this 
class  of  geographical  observations  is  scarcely  inaugurated,  and  that  it 
would  require  an  enormous  staff  of  savants,  which  does  not  at  present  ex- 
ist. We  are  therefore  compelled  to  form  rather  rough  estimations  as  to 
the  results  of  the  labor  of  rivers;  this  is  the  case  as  regards  the  Hoang- 
ho,  which  is  probably  more  loaded  with  alluvium  than  any  river  in  the 
Old  World. 

This  river  owes  its  name,  Hoang  (yellow),  to  its  muddy  sediment,  which, 
far  out  at  sea,  soils  the  purity  of  the  sea-water,  and  is  carried  by  the  cur- 
rents as  far  as  the  coasts  of  Cor-ea.  The  delta  which  it  has  formed  during 
the  present  period  extends  over  at  least  96,000  square  miles,  and  consti- 
tutes one  of  the  most  important  provinces  in  China.  The  tracts  of  allu- 
vium have  joined  to  the  main  land  the  mountainous  mass  of  Chantung, 
which  once  stood  alone  in  the  midst  of  the  sea.  Fresh  islets  have  slowly 
risen  from  the  bed  of  the  sea,  and  the  detritus  is  deposited  in  quantities 
80  great  that,  according  to  a  calculation  made  by  Staunton  at  the  end  of 
the  last  century,  they  would  be  sufficient  in  the  course  of  sixty-six  days  to 
form  an  isle  a  square  mile  in  extent  and  118  feet  in  depth.  According  to 
the  calculations  of  the  same  author,  the  whole  of  the  Yellow  Sea  is  des- 
tined to  disappear  entirely  in  about  24,000  years ;  but  this  period  should 
be  at  least  doubled,  for  the  waters  of  this  sea  are  much  deeper  than  Staun- 
ton stated. 

The  English  authors  who  have  written  on  the  subject  of  the  lower  re- 
gions of  the  Sunderbnnds — that  prodigious  mass  of  alluvium  brought 
down  by  the  Ganges  and  the  Brahmapootra,  the  terrible  "  son  of  the  Brah- 
mah" — afford  us  but  uncertain  information  as  to  the  lengthening  of  the 
mouths  of  the  rivers.  According  to  Rennell,  the  Ganges  alone  sends  down 
in  its  water  from  five  to  six  cubic  yards  of  mud  a  second ;  nevertheless, 
the  line  of  shore  extending  from  the  mouth  of  the  Hoogly  to  the  estuary 
of  Iluringota,  which  consequently  limits  the  Gangetic  portion  of  the  delta, 

Z 


354 


THE  EARTH. 


appears  to  have  been  subject  to  but  very  slight  modifications  during  his- 
toric times.  The  promontories  and  the  islets  of  the  eastern  portion  of  the 
delta  encroach  much  more  rapidly  on  the  sea ;  for  on  this  side  the  waters 
of  the  Brahmapootra,  which  on  the  average  are  charged  with  twice  as 
much  mud  as  those  of  the  Ganges,  pour  into  the  Bay  of  Bengal,*  A  great 
quantity  of  the  alluvium  which  is  brought  down  by  the  two  rivers  is  lost 
in  the  immense  depths  of  the  marine  depression,  which  lies  about  31  miles 
from  the  mouth  of  the  Ganges,  which  is  called  the  "  Great  Swatch." 

The  Nile — that  typical  river  which  was  the  subject  of  study  to  the 
Egyptian  hierophants  thousands  of  years  ago — which  spreads  out  the 
graceful  delta  formed  of  its  own  alluvium,  is  incomparably  better  known 
as  regards  its  lower  course  than  any  river  of  Asia.  This  great  water- 
course, which  may  be  compared  in  the  length  of  its  bed  to  the  Mississippi 


Fig.  139.  Delta  of  the  Nile. 

and  the  Amazon,  scarcely  surpasses  rivers  of  the  third  class,  such  as  the 
Rhone  or  the  Po,  in  the  importance  of  its  liquid  mass,  and  is  much  inferior 
to  them  in  the  quantity  of  its  alluvium.  It  has  been  calculated  that  if  all 
the  mud  brought  down  by  the  mouths  of  the  Nile  was  thrown  up  uni- 
formly on  the  coast,  the  latter  would  advance  about  1 3  feet  a  year.  The 
low  points  of  alluvium  which  are  deposited  near  the  Rosetta  and  Damietta 
mouths  increase  on  the  average — the  one  34  acres,  and  the  other  39  acres, 
*  Ferguson,  Zeitschrift  fur  Erdkunde,  1864. 


DELTA  OF  THE  PO.  355 

every  year,  which  gives  only  three  feet  of  annual  progress  for  the  front  of 
the  delta,  the  convexity  of  which  is  186  miles  in  length.  If  the  advance 
of  the  alluvial  deposits  was  not  more  rapid  during  past  ages  than  it  is  at 
present,  it  must  have  taken  the  Nile  no  less  than  74,253  years  to  deposit, 
grain  by  grain,  the  triangular  plain  of  the  delta,  comprising  an  area  of 
8610  square  miles.* 

The  fact  is,  that  the  Nile  leaves  the  greater  part  of  its  alluvium  on  the 
plains  by  the  river-side ;  added  to  this,  the  extension  of  the  water  over 
the  two  banks,  and  the  diminution  of  the  current  which  results,  necessarily 
cause  the  fall  of  a  certain  quantity  of  sediment  on  the  bottom  of  the  river- 
bed. The  French  savayits  of  the  Egyptian  expedition  found  that  the  rise 
in  the  bottom  averaged  4 '960  inches  a  century.  This  gradual  elevation 
of  the  bed  doubtless  corresponds  with  a  similar  change  in  the  level  of  the 
two  banks  of  the  river.  By  measuring  the  bed  of  alluvium  in  which  the 
statue  of  Remeses  EL  is  buried  at  Memphis,  Mr.  Horner  came  to  the  con- 
clusion that  during  the  last  3215  years  the  soil  of  Egypt  had  risen  3*043 
inches  in  each  century.  It  is  probable  that  in  future  the  soil  will  be  raised 
more  and  more  rapidly  every  year,  owing  to  the  "  warpings"  which  are 
incessantly  carried  on  by  the  agricultural  inhabitants  on  each  side  of  the 
river.  Now  that  a  vast  system  of  skillful  cultivation  has  appropriated 
the  banks  of  the  Nile,  and  that  steam-pumps  are  drawing  off  the  water  of 
the  river  in  every  season,  the  liquid  discharge  and  the  mass  of  sediment 
must  diminish  at  the  mouth ;  and  if  this  impoverishment  of  the  Nile  con- 
tinues to  go  on  in  the  same  proportion,  we  might  perhaps  calculate  the 
future  date  when  the  Nile,  being  exhausted  by  the  irrigation  canals,  will 
no  longer  send  down  to  the  Mediterranean  either  a  drop  of  water  or  a 
grain  of  sand. 

It  may  be  readily  understood  that  the  best  known  river-delta  must  be 
looked  for  in  Europe,  and  in  that  country  of  Europe  which,  for  so  many 
centuries,  has  devoted  itself  most  earnestly  to  all  questions  relating  to  hy- 
draulics and  irrigation.  The  delta  we  speak  of  is  that  of  the  Po.  Owing 
to  the  testimony  afforded  by  history,  the  monuments  left  by  the  ancients, 
and  the  operations  of  the  engineers  of  the  Middle  Ages,  we  are,  enabled  to 
follow  with  the  mind's  eye  the  progress  made  by  the  alluvium  of  the  river 
during  the  last  twenty  centuries.  In  some  spots,  especially  round  the  la- 
goon of  Comacchio,  there  are  secondaiy  deltas,  the  encroachments  of  which 
may  be  measured  with  mathematical  exactitude,  for  these  tracts  are,  so  to 
speak,  of  human  creation,  and  have  been  altogether  deposited  since  the 
opening  of  artificial  channels  and  sluices. 

Notwithstanding  the  shortness  of  its  course,  the  Po  is  one  of  the  mosl 
remarkable  "  working  rivers"  in  the  whole  world.  The  gradual  subsidence 
of  the  shores  of  the  Adriatic,  which  is  estimated  by  Donati  at  six  feet  at 
least  since  the  foundation  of  Venice,  does  not  prevent  the  river  encroach- 
ing without  intermission  on  the  domain  of  the  sea.  Ravenna,  which  once, 
like  another  Venice,  stood  in  the  midst  of  lagoons,  its  outer  rampait  being 
*  Eli  Lombnrdini,  Essai  sur  F Ilydroloyie  du  NiL 


356 


THE  EARTH. 


Fig.  140.  Mouths  of  the  Po. 


bathed  by  the  Adriatic,  is  now  situated  far  from  the  gulf,  in  a  plain  filled 
with  the  alluvium  of  the  Po.  We  also  know  that  the  town  of  Adria,  the 
ancient  emporium  of  the  Adriatic,  to  which,  indeed,  it  gave  its  name,  is 
now  21  miles  from  the  extreme  point  of  the  shore.  This  is  a  proof  that 
in  two  thousand  years  the  annual  average  progress  of  the  delta  has  been 
55  feet ;  but  at  the  present  day  the  advance  of  the  alluvial  tracts  is  much 
more  rapid.  The  patient  investigations  of  M.  Lombardini  have  established 
the  fact  that  the  river  brings  down  every  year  15,015,600  cubic  yards  of 
mud  and  ooze* — that  is,  about  1.781  cubic  yards  a  second,  and  enlarges 
the  shore  of  its  delta  76  yards.  A  chain  of  dunes,  now  left  inland  by  the 
encroachments  of  the  alluvial  deposit,  still  points  out  the  direction  of  the 
former  sea-coast.  The  enormous  amount  of  increase  in  the  deposit  at  its 
mouth,  which  is  thus  accomplished  by  a  river  of  the  third  class,  is  readily 
explained  by  the  embankments,  which  compel  the  Po  to  carry  down  to 
the  sea  the  whole  of  its  alluvium,  whilst  the  Nile  and  the  Ganges,  during 
each  period  of  flood,  spread  over  a  great  area  of  land,  the  level  of  which 
t"hey  raise  by  their  deposits. 

The  Rhone  is  the  most  active  among  the  French  rivers  in  the  forma- 
tion of  a  delta.  The  promontory  deposited  by  its  current  in  the  open  sea 
projects  much  more  decidedly  beyond  the  regular  line  of  coast  than  the 
delta  of  the  Nile,  and  advances  every  year  with  a  rapidity  which  may  al- 

*  According  to  M.  Ch.  Hartley,  the  Danube,  which  discharges  fi^t  times  as  much  water  as 
the  Po,  brings  down  to  the  sea  only  46,500,000  cubic  yards  a  year. 


ALLUVIUM  OF  THE  RHONE. 


357 


Fig.  141.  Delta  of  the  Rhone  in  the  Fourth  Century  and  at  the  Proseiu  Time. 


most  be  compared  to  that  of  the  Po.  In  the  fourth  century  the  town  of 
Aries  was  only  16  miles  from  the  sea,  while  at  the  present  day  it  is  29 
miles  removed. from  it.  The  advance  of  the  alluvium  has,  therefore,  been 
13  miles  during  the  space  of  fourteen  centuries,  or  about  52  feet  a  year.* 
The  annual  average  elongation  of  the  shores  of  the  principal  branch  of  the 
river  is,  therefore,  about  164  feet.  J3ut  this  does  not  prove  that  the  debris 
brought  down  by  the  river  are  increased  threefold,  in  consequence  of  the 
embankment  of  the  land  by  the  river-side ;  for  the  Rhone  has  frequently 
shifted  the  position  of  its  outlets  by  opening  them  alternately  on  both 
sides  of  the  banks  of  mud  caused  by  its  own  deposits.  In  this  way  the 
increase  of  the  delta  takes  place  at  several  points  in  succession ;  on  one 
side  the  alluvium  encroaches  rapidly,  and  in  other  places  it  remains  almost 
stationary. 

In  the  Rhone,  as  in  the  Po,  an  endeavor  has  been  made  to  estimate,  by 
means  of  the  annual  discharge,  the  quantity  of  matter  deposited  by  the 
river.  This  mass  is  about  22,000,000  cubic  yards  every  year.  It  certain- 
ly is  a  fact  that,  by  direct  measurements  of  the  increase  of  the  delta,  and 
by  soundings  made  on  the  bar,  M.  Reybert  found  that  the  total  quantity 
of  matter  brought  down  from  1841  to  1858  amounted  to  419,000,000  of 
cubic  yards,  which  would  be  equivalent  to  an  annual  increase  of  25,000,000 
a. year;  but  this  difference  may  be  explained  by  taking  into  account  the 
enormous  quantity  o^  infusoria  and  small  shell-fish  which  exist  in  all  the 
newly-formed  soft  banks.  Some  specimens  of  the  mud  taken  from  the 
mouth  of  the  Rhone  contain,  as  M.  Delesse  has  ascertained,  as  much  as  30 
*  E.  Desjardins,  Aj>er(u  Historique  sur  les  Embouchifres  du  lihSne. 


358  ^^^  EARTH. 

per  cent,  of  carbonate  of  lime,  proceeding,  no  doubt,  from  the  remains  of 
the  shell-fish.  It  also  appears  that  the  proportion  of  the  alluvium  of  the 
Rhone  which  is  brought  down  to  the  sea,  and  afterward  carried  away  by 
the  currents  to  distant  shores,  is  very  slight.  Almost  all  the  mud  is  ab- 
sorbed in  the  construction  of  the  delta,  and  forms  the  teys  or  muddy  islets 
which  make  their  appearance  on  each  side  of  the  mouth.  The  soil  Avhich 
is  thus  brought  down  by  the  river  is  generally  very  fertile.  The  mud  of 
the  Rhone  is  no  less  productive  than  that  of  the  Nile,  and  sanitaiy  and 
irrigatory  operations  would  soon  render  La  Camargue  another  Egypt.  In 
this  respect  France  has  much  to  learn  from  the  ancient  land  of  the  Pha- 
raohs. 

The  delta  of  the  Mississippi  advances  even  more  rapidly  than  that  of 
the  Po.  Among  all  the  questions  in  respect  to  the  great  river  of  the  New 
World,  the  yearly  prolongation  of  its  alluvium  has  most  of  all  excited  the 
curiosity  of  science.  How  many  yards  does  the  Mississippi  advance  into 
the  sea  during  the  course  of  each  year?  How  many  square  miles  does  it  add 
to  the  main  land  in  a  century  ?  How  many  thousands  of  years  must  it  have 
been  at  work  in  forming  its  delta,  and  depositing  its  enormous  burden  of 
alluvium  ?  Many  geologists  have,  each  in  their  turn,  endeavored  to  an- 
swer these  questions  by  basing  on  data  which  are  sometimes  only  hypo- 
thetical the  very  different  results  at  which  they  have  arrived.  Thus  M. 
Elie  de  Beaumont,  who  at  that  time  had  not  the  necessary  elements  at  his 
disposal,  estimated  the  progress  of  the  delta  at  382  yards  a  year.  M. 
Thomassy,  comparing  the  ancient  French  charts  with  the  American  sur- 
veys, has  felt  warranted  in  fixing  the  annual  conquest  effected  by  the  Mis- 
sissippi at  about  110  yards.  Messrs.  Humphreys  and  Abbot,  looking  upon 
the  old  chart  as  being  too  incorrect  to  serve  as  the  base  of  a  serious  calcu- 
lation, are  satisfied  with  comparing  the  charts  ofTalcott  and  of  the  Coast 
Survey,  and  judge  the  annual  prolongation  of  the  delta  to  be  86  yards. 
M.  Ellet,  one  of  the  most  conscientious  investigators  of  the  action  of  the 
river,  reduces  the  probable  elongation  of  the  delta  to  22  feet,  so  as  to  make 
allowance  for  the  erosion  exercised  by  the  sea.  Lastly,  M.  Kohl,  whose 
hypotheses  it  is  very  difficult  to  understand,  even  if  you  have  the  maps 
before  you,  maintains  that  the  delta  of  the  Mississippi  remains  nearly  sta- 
tionary.* It  must  be  confessed  that  the  differences  on  the  point  would  be 
serious  enough  to  render  doubt  "  the  best  pillow  for  the  wise  man"  if  it 
were  not  that  the  calculations  of  M.  Thomassy  and  the  learned  explorers, 
Humphreys  and  Abbot,  undoubtedly  surpass  all  the  others  in  scientific 
value.  The  average  advance  of  the  delta  during  the  two  last  centuries 
must  therefore  be  estimated  at  from  86  to  110  yards. 

This  rapid  progress  in  the  alluvium  is  perhaps  very  much  owing  to  the 
cutting  down  of  the  forests,  which  has  rendered  the  soil  of  the  banks  much 
more  movable.f  To  this  cause  for  the  growth  of  the  delta  must  be  added 
the  construction  of  high  embankments  on  the  banks  of  the  Mississippi  and 

*  Zeitschrift  fiir  Erdkunde,  September,  18(52. 

t  Marcou,  Bulletin  de  la  Societe  de  Geographie,  July,  1865. 


DELTAS.  359 

its  tnbut£^ries ;  for,  as  only  a  small  portion  of  the  mud  is  able  to  settle  at 
the  sides,  a  mucli  more  considerable  mass  is  carried  down  to  the  mouth ; 
nevertheless,  the  delta  is  not  increased  in  proportion.  The  more  the  points 
of  alluvium  gain  on  the  water,  the  deeper  is  the  spot  in  the  gulf  in  which 
the  matter  (estimated  at  seven  cubic  yards  a  second)  is  deposited.  At 
the  lower  extremity  of  the  delta  of  the  Mississippi,  the  thickness  of  the  bed 
of  sediment  is  not  less  than  98  feet ;  and  soundings  have  shown  that  the 
river  will  soon  reach  the  edge  of  the  deep  abyss  through  which  the  Gulf 
Stream  flows.  At  11  miles  from  the  southwest  channel,  the  bottom  of  the 
sea  is  885  feet  from  the  surface,  and  this  depth  rapidly  increases  to  more 
than  5000  feet.  Being,  of  course,  unable  to  fill  up  these  gulfs  where  the 
rapid  currents  would  carry  the  alluvium  into  the  open  sea,  the  Mississippi 
must  be  content  with  obstructing  the  lateral  bays,  or  with  extending  to- 
ward the  east,  in  the  direction  of  Florida.  Some  day  the  delta  of  this 
liver  will  be  bounded  on  the  southern  side  by  a  rapid  slope,  like  that  which 
is  formed  by  the  Rhone  in  the  Lake  of  Geneva,  and  by  the  Congo  in  the 
Gulf  of  Guinea.  At  the  mouth  of  this  latter  water-course  the  sounding- 
lead  falls  rapidly  from  30  to  1600  or  2000  feet. 

When  the  river-outlets  are  left  to  themselves,  the  spot  in  the  river  where 
the  bifurcation  takes  place  gradually  shifts  its  position  in  a  down-stream 
direction  in  proportion  as  the  mouths  advance  toward  the  sea.     In  fact, 


Fig.  142.  Height  of  tlie  Layers  in  the  Delta. 


the  current  striking  against  the  upper  point  of  the  delta  must  necessarily 
wash  away  the  two  banks  of  the  island  which  it  has  itself  formed  by  the 
deposit  of  its  alluvium.  A  remarkable  instance  of  this  alteration  in  the 
place  of  bifurcation  of  the  river-outlet  may  be  noticed  in  the  Egyptian 
delta.  At  the  time  of  Herodotus,  Memphis  was  the  spot  where  the  Nile 
divided  into  two  branches;  it  now  forms  its  fork  at  Cairo,  more  than  18 
miles  from  the  spot  where  it  took  place  2400  years  ago.  The  upper  point 
of  the  delta  will  henceforth  remain  stationary,  owing  to  the  barriers  con- 
structed just  at  the  beginning  of  the  two  principal  branches  of  the  river. 

The  elongation  of  the  delta  has  a  proportionate  and  constant  tendency 
to  raise  the  bed  of  the  river  above  the  mouth.  The  calm  and  immense 
river  which  empties  itself  into  the  sea  obeys  the  very  same  laws  as  the 
boisterous  torrent  pouring  into  a  lake.  In  proportion  as  it  pushes  its 
branches  farther  into  the  sea,  it  must  form  a  slope  considerable  enough  to 
insure  the  discharge  of  the  mass  of  water.  This  slope  can  only  be  pro- 
duced by  the  gradual  raising  of  the  river-bed. .  It  is  evident  that  this  rise 
will  be  the  more  rapid  the  better  the  shores  are  protected  by  embank- 
ments against  inundations;  for  the  alluvium  must,  in  this  case,  all  descend 
to  the  sea,  and  lengthen  the  extreme  points  of  the  delta. 

The  results  produced  on  the  action  of  rivers  by  lateral  embankments 


360  2^2/^  EARTH. 

have,  however,  been  singularly  exaggerated.  Pessimists  have  often  point- 
ed to  the  example  of  the  Po  as  a  proof  of  the  i-apid  heightening  of  the  riv- 
er-level which  is  brought  about  by  the  construction  of  embankments; 
"  but  this  oft-repeated  assertion  is  not  based  on  any  real  fact.  Cuvier  was 
entirely  mistaken  in  stating,  according  to  a  communication  from  M.  de 
Prony,  that  the  surface  of  the  water  of  the  Po  is  now  higher  than  the  roofs 
of  the  houses  in  Ferrara."*  This,  unfortunately,  is  one  of  those  accredited 
errors  which  it  is  difficult  to  dispel,  on  account  of  the  great  names  which 
countenance  them.  Elia  Lombardini  has  proved,  by  strict  measurements, 
that  the  mean  level  of  the  P(J  exceeds  in  but  very  few  spots  the  level  of 
the  ground  in  the  adjacent  country.  In  1830,  at  the  time  of  one  of  the 
highest  floods  of  the  century,  the  surface  of  the  Po  was  scarcely  ten  feet 
above  the  level  of  the  pavement  in  front  of  the  palace  at  Ferrara.  The 
mean  height  of  the  water  over  the  whole  course  of  the  river  is  considera- 
bly below  that  of  the  neighboring  plains.  To  make  up  for  this,  the  streams 
of  the  Reno,  the  Adige,  and  the  Brenta,  which  empty  into  the  delta  of  the 
Po,  have  certain  portions  of  their  beds  higher  than  the  adjacent  country. 
The  fact  is,  that,  having  so  lately  left  the  mountain  gorges,  they  still  retain 
their  characteristics  as  torrents,  and,  like  all  mountain  streams,  raise  a 
bank  of  debris  below  the  ravines  of  erosion.f  The  exceptional  height  of 
the  Adige,  the  Reno,  and  the  Brenta  must  not,  therefore,  be  attributed  to 
the  dikes  which  border  the  lower  portion  of  the  course  of  these  streams, 
but  to  the  impetuosity  of  the  water  above.  The  calculations  of  MM. 
Humphreys  and  Abbot  prove  that  the  mouths  of  the  Mississippi  must 
project  24  miles  farther  into  the  sea  for  the  river  to  rise  only  one  foot 
under  the  i-amparts  of  Fort  St.  Philip,  31  miles  above  the  southwest  chan- 
nel. 

If,  however,  rivers  which  are  subject  to  high  floods,  such  as  the  Nile, .the 
Po,  and  the  Mississippi,  are,  during  inundations,  higher  in  level  than  the 
plains  by  the  river-side,  this  fact  is  owing  to  the  lining  of  alluvium  which 
is  gradually  formed  on  the  banks.  Dui-ing  the  period  of  flood,  the  waters 
which  pour  over  the  banks  are  retarded  by  a  thousand  various  obstacles 
— trunks  of  trees,  bunches  of  plants,  mounds,  palisades,  buildings — and  con- 
sequently they  deposit  on  the  ground  much  of  the  sediment  which  they 
contain ;  before  they  leave  the  banks  and  flow  far  and  wide  into  the  plains 
they  are  comparatively  purified.  The  efi^ct  of  this  is  a  gradual  elevation 
of  the  banks  and  the  ground  near  them  to  a  level  somewhat  above  that  of 
the  country  generally.  Above  New  Orleans  the  natural  inclination  of  the 
soil  is  very  marked ;  from  the  shores  of  the  Mississippi  to  the  marshes  in 
the  interior  the  difierence  in  level  is  not  less  than  13  to  16  feet,  and  at 
some  points  even  this  considerable  slope  is  exceeded.  The  banks  of  the 
islands  scattered  about  in  the  lower  courses  of  rivers  are  likewise  raised 
by  inundations  to  a  point  above  the  level  of  the  surrounding  country.  The 
Lower  Parana,J  the  Volga,§  and  a  number  of  other  large  water-courses 

*  Discours  sur  les  Revolutions  du  Globe.  t  Vide  above,  p.  293. 

X  Martin  ile^ovissY,  Confederation  Argentine.  §  De  Baer,  Kaspische  Studien. 


ELEVATION  OF  BIYEB  ABOVE  ALLUVIUM.  361 

present,  near  their  mouths,  multitudes  of  islands,  the  raised  banks  of  which 
circle  round  pools  or  marshes. 

The  elevation  of  the  lower  course  of  a  river  above  the  surface  of  the 
surrounding  plains  explains  in  the  most  simple  way  the  continual  shift 


Fig.  143.  Section  of  the  Miasisisippi  at  Flaqaemiue. 

ing  of  the  outlets  of  the  delta.  As  soon  as  a  breach  is  made  in  the  lining 
of  the  bank,  a  considerable  portion  of  the  running  water  immediately 
escapes  through  this  opening,  and  descends  to  the  sea  over  a  new  bed 
which  it  hollows  out  for  itself  across  the  low-lying  tracts,  marshes,  and 
lagoons ;  these  are  natural  crevices,  similar  to  those  which  occur  in  em- 
bankments raisedxby  man's  labor.  Thus,  when  the  economy  of  a  river 
has  not  been  modified  by  human  agency,  its  outlets  are  of  a  changing 
character,  and  move  across  the  delta,  depositing  their  sediment  in  the  la- 
goons, so  as  gradually  to  elevate  the  soil,  and  to  bring  it  every  where  to 
the  level  of  the  high  floods.  Every  delta  becomes  modified,  even  during 
the  historical  period,  in  the  number,  direction,  and  importance  of  its 
branches.  Of  the  seven  famous  mouths  of  the  Nile,  five  have  now  ceased 
to  exist  except  during  floods;  the  two  which  still  remain  open — those  of 
Rosetta  and  Damietta — appear,  according  to  Herodotus's  statement,  to 
have  been  dug  out  by  the  labor  of  man.  During  the  last  3000  years,  the 
branches  of  the  Lower  Hoang-ho  have  undergone  similar  modifications  in 
their  course,  which  are  more  remarkable  on  account  of  the  immense  ex- 
tent of  ground  over  which  they  have  constantly  wandered.*  Still  more 
strangely,  the  Amou-Daria  in  Tartary,  which  now  falls  into  the  sea  of 
Aral,  was  in  former  days  a  tributary  of  another  sea,  and  flowed  into  the 
Caspian  ;  the  traces  of  its  abandoned  bed  may  still  be  seen  here  and  there 
in  the  desert. 

In  consequence  of  the  incessant  modifications  to  which  the  lower  por- 
tions of  rivers  are  subject,  it  often  occurs  that  two  water-courses,  which 
were  once  perfectly  distinct  and  independent  of  one  another,  become 
united  in  their  deltas  and  principal  outlets.  We  may  mention  the  in- 
stance of  the  Shat-el-Arab.  In  like  manner,  the  Adige  and  the  Po,  which 
communicate  with  one  another  by  lateral  branches,  have  a  tendency  to 
join  one  another  completely  in  a  common  bed,  and  nothing  but  extensive 
operations  has  prevented,  up  to  the  present  time,  the  perfect  junction  of 
these  two  rivers.  The  Mississippi,  so  remarkable  in  all  other  respects, 
presents,  according  to  Ellet,  the  phenomenon  of  three  former  rivers  united 
in  one.  At  one  time  the  River  Ouachita  ran  down  to  the  sea  throng  hthe 
Atchafalaya,  which  is  now  an  overflow-channel  ofthe  Mississippi,  but  Av^as 
then  a  distinct  river.  The  Red  River,  too,  flowed  in  the  valley  of  the 
Teche,  where  it  has  left  numerous  traces  of  its  passage.  The  opposite 
windings  ofthe  Red  River  and  the  Mississippi  gradually  approached  one 

*  Vide  above,  p.  3.">3. 


362 


THE  EARTH. 


io    E.of  Paris 


Fig.  144.  Ancient  Course  of  the  Amou-Daria. 


another  and  then  united ;  the  Ouachita- Atchafalaya  has  been,  as  it  were, 
cut  into  two  parts,  one  of  which,  the  noi'thern  portion,  is  become  an  afflu- 
ent, and  the  other,  the  southern  portion,  an  effluent  of  the  Mississippi. 
Similar  phenomena  are  observed  in  the  delta  common  to  the  Ganges  and 
the  Brahmapootra.  There  seems  to  be  a  real  conflict  between  the  branch- 
es of  these  two  rivers ;  they  first  come  together  and  are  then  mutually  re- 
pelled ;  they  sever  one  another  and  fill  each  other  up.* 

Thus,  while  in  some  cases  distinct  rivers  unite,  others,  on  the  contraiy, 
which  were  once  combined,  are  now  separate,  and  take  contrary  direc- 
tions. As  a  sti'iking  instance  of  this  double  series  of  hydrological  phe- 
nomena, we  may  mention  the  two  rivers  of  Cilicia,  once  called  the  Sarus 
and  the  Pyramus,  now  known  as  the  Seihoun  and  the  Djihoun.  These 
streams,  which  project  their  alluvial  deposits  more  than  six  miles  beyond 
the  outline  of  the  former  coast,  fall  into  the  sea  sometimes  through  two 
distinct  mouths,  sometimes  through  one  outlet  common  to  the  two  rivers. 
Since  the  days  of  Xenophon,  the  two  streams,  which  then  flowed  in  beds 
some  distance  from  one  another,  have  united  three  times,  and  three  times 
have  again  separated.  In  the  space  of  twenty-three  centuries,  says  M. 
Langlois,  six  complete  revolutions  have  taken  place  in  succession  in  the 
course  of  action  of  the  Sarus  and  the  Pyramus. 

.  *  Yergason,  Zeitsc/irift/iir  Erdkunde,i86i. 


BASS  OF  RIVERS.  363 


CHAPTER  LIV. 

BARS    OF    RIVERS. — OPERATIONS    UNDERTAKEN   FOR   DEEPENING   THE 
MOUTHS    OF   RIVERS. 

Nothing  is  more  vai'iable  than  the  chanDels  at  the  mouth  of  a  river. 
Thus — only  to  mention  the  Mississippi — this  river  has  now  five  channels, 
the  southwest,  the  south,  the  southeast,  the  north,  and  the  Loutre,  which 
is  a  ramification  of  the  one  preceding.  Sometimes  one,  and  sometimes 
another  of  these  outlets  becomes  the  real  mouth  of  the  river,  and  the 
stream  takes  to  them  and  abandons  them  in  turn.  The  fact  is,  that  the 
Mississippi,  having  considerably  elongated  its  principal  outlet  by  the  al- 
luvium it  has  brought  down,  is  compelled  to  seek  some  bed  which  is  short- 
er, and  consequently  more  inclined,  in  order  to  pour  down  its  mass  of 
water ;  when  this  fresh  outlet  is  likewise  pushed  out  too  far  into  the  sea 
to  aflbrd  the  requisite  slope,  the  river  turns  either  to  the  right  or  left  to 
clear  for  itself  a  third  place  of  issue.  At  the  time  of  the  first  attempts  at 
colonization  in  Louisiana,  the  southeast  channel  was  the  principal  one ; 
but  this  gradually  became  obstructed,  and  the  northeast  mouth  was  next 
the  most  important.  The  mass  of  water  in  this  channel  diminished  every 
year;  and  in  1853  there  was  not  more  than  8  feet  of  water  on  the  bar, 
and  small  coasters  were  the  only  vessels  which  ventured  over  it.  Since 
1843,  the  southwest  channel  has  become  the  real  mouth  of  the  river, 
through  which  almost  all  large  ships  try  to  enter.  In  1853  there  were 
16^  feet  of  water;  but  constant  labor  was  necessary  to  maintain  even  this 
depth,  for  the  quantity  of  water  constantly  tends  to  diminish,  while  in  the 
Loutre  Channel  it  is  gradually  increasing.  Some  hydrographere  think 
that  this  latter  mouth  will  ultimately  become  the  true  Mississippi ;  it  al- 
ready has  13  feet  of  water  on  the  bar;  and,  in  order  to  avoid  a  considera- 
ble circuit,  nearly  all  the  steamers  running  betwfeen  Cuba,  Mobile,  and 
New  Orleans  now  attempt  to  pass  through  it. 

However  much  they  may  shift  their  course,  still  most  rivers  are  ob- 
structed by  a  bar  of  sand  or  mud,  to  which  mariners  have  given  the  name 
of  "  bar."  These  banks  of  alluvium  are,  for  the  most  part,  deposited  in 
the  form  of  a  crescent,  off  the  mouth  of  the  river,  and,  turning  their  con- 
vex sides  toward  the  open  sea,  mark  the  precise  spot  of  the  line  of  break- 
ers which  rise  in  rough  weather.  They  may  be  deposited  in  different 
modes,  according  to  the  quantity  and  impetus  of  the  river-water,  the 
mass  of  sediment  which  the  latter  holds  in  suspension,  the  configuration  of 
the  coast,  and  the  general  direction  of  the  winds  and  currents  out  at  sea. 
There  are,  however,  a  few  hydrological  problems  which  have  given  rise  to 
lively  discussions  among  geographers  and  engineers,  for  which,  too,  many 


364 


THE  EARTH. 


various  or  contradictory  solutions  have  been  propounded.  The  fact  is, 
that  the  question  is  altogether  a  complex  one,  and  presents  itself  under  a 
new  aspect  at  the  mouth  of  each  particular  river.  It  certainly  is  the  case 
that,  as  regards  all  rivers,  the  collision  of  the  two  liquid  masses  flowing  in 


Wa\esof  iheSea 


Fig.  145.  Lougitudinal  Section  of  the  Bar  of  the  MississippL 

contrary  directions  is  the  primary  cause  of  the  formation  of  bars,  bu  the 
materials  which  are  employed  and  the  progress  of  the  work  vary  singu- 
larly. 

At  first  sight,  the  origin  of  a  bar  seems  a  matter  easily  to  be  under- 
stood, especially  in  the  case  of  rivers  with  waters  much  charged  with  mud. 
It  is  thought  that  the  current  of  fresh  water,  being  suddenly  arrested  in 
its  career  by  the  sea  water,  immediately  lets  drop  on  the  bottom  the  mat- 
ter which  it  held  in  suspension,  and  thus  gradually  forms  the  kind  of  sill 
which  rises  between  the  bed  of  the  river  and  the  ocean.  This,  however,  is 
not  the  exact  mode  of  formation.  The  flow  of  fresh  water,  being  but  lit- 
tle retarded,  continues  its  movement  above  the  salt  water  coming  in  a 
contrary  direction.  The  sediment  which  is  let  fall  by  the  current  of  the 
river  is  taken  hold  of  by  the  counter-current  and  borne  up  stream.  At 
the  same  time,  the  heavier  alluvium,  which  makes  its  way  to  the  sea  by 
gliding  over  the  bottom  of  the  river-bed,  is  arrested  in  its  progress,  and  is 
mingled  with  the  sand  and  the  innumerable  organic  remains  driven  in  by 
the  waves.  Thus  an  increasing  cushion  of  mud  is  formed  in  front  of  the 
rising  tide  flowing  to  meet  the  river,  and  in  this  way  the  heaps  of  debris 
which  constitute  the  bar  are  gradually  accumulated.  This  obstacle,  being 
produced  by  the  shock  of  two  opposing  currents,  shifts  coincidently  with 
the  scene  of  the  conflict.  During  floods,  the  impetus  of  the  mass  of  fresh 
water  becomes  suflSciently  strong  to  remove  the  whole  bar  and  to  carry  it 
farther  in  advance ;  but,  on  the  other  hand,  when  the  water  of  the  river  is 
low,  the  tide  resumes  the  preponderance,  and  the  bar  is  again  driven  back. 
The  barrier  shifts  its  place,  sometimes  in  one  direction,  sometimes  in  an- 
other, and  is  incessantly  seeking  to  preserve  its  equilibrium  between  the 
two  opposed  forces  which  impel  it. 

The  bars  of  the  delta  of  the  Mississippi  may  be  quoted  as  an  instance  of 
this  mode  of  formation.  Over  the  bar  which  obstructs  the  entry  of  the 
principal  channel,  and  the  most  practicable  of  all  those  on  the  coast  of  the 
Gulf,  .there  is  an  average  depth  of  16^  feet.  The  alluvium  of  the  bed, 
being  kept  in  constant  motion  by  the  waves  and  the  current  of  the  river, 


BASS  OF  RIVERS.  365 

is  in  an  almost  liquid  state.  Vessels  have  been  known  to  cross  the  bar 
Avithout  any  other  assistance  than  their  sails,  although  their  hulls  were, 
for  more  than  half  a  mile,  buried  in  the  mud  lo  a  depth  of  six  feet.  Not- 
withstanding the  soft  nature  of  the  ooze,  vessels  may  still  incur  consider- 
able danger  in  crossing  the  bar.  Those  that  do  not  avail  themselves  of  a 
steam-tug  are  sometimes  taken  athwart  by  the  wind  and  driven  irretriev- 
ably upon  the  banks.  It  is  often  impossible  to  get  them  off  again ;  the 
motion  of  the  keel  stirs  up  and  sends  into  the  current  the  smaller  particles 
of  the  mud,  but  the  heavy  sand  remains,  and  ultimately  becomes  cemented 
round  the  bottom  of  the  ship. 

There  are  some  bars  which  are  almost  entirely  the  work  of  the  sea; 
these  are  banks  of  sand  or  shingle  which  the  waves  throw  up  across  the 
outlet  of  a  river,  thus  continuing  the  line  of  shore.  Barriers  of  this  kind 
form  in  front  of  water-courses  running  into  a  sea  agitated  by  violent 
storms,  or  raised  every  day  by  a  very  strong  tide.  The  flow  coming  from 
outside  ascends  far  into  the  river-mouth,  and  forces  the  current  meeting  it 
to  deposit  its  heavier  alluvium  at  some  considerable  distance  above  the 
bar  properly  so  called.  The  earthy  particles  held  ip  suspension  by  the 
current  of  the  river  can  not  be  precipitated  on  account  of  the  continual 
agitation  which  is  kept  up  at  the  entry  by  the  breakers  and  the  swell; 
they  remain  mixed  with  the  masses  of  water,  and  are  driven  up  stream  by 
the  flow,  or  carried  out  to  sea  by  the  ebbing  tide.  Even  the  fine  sand 
which  the  waves  throw  up  on  the  bar  is  not  allowed  to  remain  there  for 
long ;  it  is  again  stirred  up  by  the  water  which  brought  it,  and  it  finds  a 
resting-place  only  in  those  spots  where  the  motion  of  the  waves  ceases. 
The  heavy  sand,  the  shingle,  and  the  stones  which  the  waves  drive  before 
them  without  carrying  them  along  in  eddies,  are  the  only  materials  which 
constitute  the  bar.  Like  the  banks  of  mud  in  river-deltas,  this  line  of  de- 
bris is  incessantly  shifting  its  place,  sometimes  up  stream  and  sometimes 
down  stream,  seeking  the  exact  line  where  an  equilibrium  exists  between 
the  ebb  and  the  flow.  When  the  river  is  flooded,  the  force  of  the  water 
running  down  carries  the  bar  farther  out  to  sea ;  on  the  contrary,  when 
the  river  is  low,  the  tide  gains  the  ascendency,  and  pushes  the  sand  up 
into  the  mouth  of  the  stream. 

In  France,  these  phenomena  have  been  best  studied  at  the  formidable 
bar  of  the  Adour.  Thanks  to  the  submarine  charts  which  the  engineere 
prepare  twice  every  month,  we  may  trace  out,  so  to  speak,  by  the  eye,  all 
the  fluctuations  of  the  bank  of  debris^  and  all  the  causes  of  its  movements 
can  readily  be  taken  into  account.  In  this  bar,  however,  there  is  every 
evidence  to  show  that  the  materials  forming  it  are  brought  up  by  the 
waves.  The  soundings  that  have  been  made  in  the  bed  of  the  Adour,  as 
far  up  as  15^  miles  above  Bayonne,  uniformly  show  a  bottom  of  mud  or 
tine  sand ;  but  it  is  ascertained  that  the  bank  at  the  mouth  is  composed 
of  heavier  sand  and  shingle,  proceeding,  no  doubt,  from  the  cliffs  of  the 
Spanish  coast.* 

*  yioxmoXs,  AnnaUa  da  Fonts  et  Chaus^et,  3d  series,  vol.  xvi. 


366  ^^^  EARTH. 

The  bars  of  rivers,  which  have  always  been  an  obstacle  and  a  source  of 
danger,  are  at  the  present  time  more  troublesome  to  deep  navigation  than 
they  have  ever  before  been.*  It  certainly  is  the  case  that,  thanks  to  the 
steam-tugs,  vessels  with  a  light  draught  of  water  are  able  to  follow  the 
direct  channel,  and  can  cross  the  difficult  part  in  the  space  of  a  few  min- 
utes; but,  nowadays,  commerce  is  no  longer  contented  to  employ  the 
small  vessels  of  former  times ;  it  requires  ships  of  heavy  burden,  carrying 
large  quantities  of  merchandise,  and  drawing  a  considerable  depth  of 
water.  Many  a  river-port,  once  the  resort  of  whole  navies,  is  now  aban- 
doned on  account  of  the  bar  which  cuts  it  off  from  the  ocean,  and  is  fre- 
quented only  by  coasting  vessels;  commercial  vitality  has  gradually  left 
it.  Thus  the  deepening  of  their  river-mouths  is  become  a  most  important 
question  in  some  sea-coast  towns.  If  they  could  only  succeed  in  doing 
away  with  the  bar,  these  towns  would  increase  suddenly  in  wealth,  popu- 
lation, and  importance.  If  the  bank  of  sand  must  remain  fixed  across  the 
outlet  of  the  river,  the  city  is  on  its  way  to  certain  ruin.  Every  engineer 
recommends  his  own  special  plan  as  being  adapted  to  avert  the  danger; 
each  promises  that  he  will  correct  those  river-outlets  which  Vauban  char- 
acterized as  "incorrigible."  But  only  too  frequently,  operations  are  un- 
dertaken without  taking  account  of  the  numerous  causes  which  determine 
the  formation  and  fluctuations  of  the  bar.  Amongst  all  the  immense 
works  which  have  been  carried  out  at  the  mouths  of  rivers,  many  have 
become  useless,  or  even  absolutely  injurious  to  navigation.  Millions  and 
millions  of  money  have  been  thus  cast  into  the  ocean  and  purely  wasted. 

The  most  simple  means,  and  that,  indeed,  which  is  always-  resorted  to 
in  the  first  place,  is  dredging  y  but  this  plan  is  evidently  merely  provi- 
sional, and  in  the  present  state  of  science  can  scarcely  be  considered  as  a 
remedy  of  a  lasting  character.  Moving  an  obstacle  is  not  doing  away 
with  it;  besides,  the  flotilla  of  dredgers  which  can  be  employed  on  a  bar 
in  removing  the  alluvium  is  always  insufficient  in  number.  Even  if  they 
were  constantly  at  Avoi'k,  there  would  be  little  or  no  result,  for  the  inex- 
haustible ocean  would  take  up  the  task  of  providing  the  alluvium  and 
raising  the  bar;  the  obstacle  would  be  merely  shifted  in  place. 

Instead  of  moving  the  mud,  the  more  simple  plan  has  often  been  tried 
of  sending  it  into  the  current  by  keeping  the  water  in  a  constant  state  of 
agitation.  For  a  length  of  time  it  has  been  a  recognized  fact  that,  aftei- 
the  passage  of  several  ships,  there  is  an  increased  depth  of  water  on  bars 
composed  of  mud  and  fine  sand :  the  particles  stirred  up  by  the  keels  are 
carried  away  by  the  current.  This  phenomenon  may  readily  be  produced 
by  artificial  means.  More  than  a  century  back  a  French  company  ap- 
plied this  remedy  in  the  principal  channel  of  the  Mississippi,  by  causing 
heavy  iron  harrows  to  be  dragged  over  the  shifting  bed  of  the  river.  Re- 
cently, in  1852,  the  same  plan  was  applied,  and  the  federal  government 
employed  on  the  bar  a  certain  number  of  steam-boats,  which  kept  the 
mud  on  the  bottom  incessantly  in  motion  by  means  of  drags  or  harrows, 
and  thus  prevented  its  precipitation.     According  to  a  popular  tradition, 


£AItS  OF  RIVERS.  367 

mentioned  by  M.  Engelhardt,  a  Turkish  pacha  formed  the  same  idea  as 
the  American  engineers.  He  obliged  every  vessel  which  left  the  Danube 
to  drag  astern,  while  crossing  the  bar,  a  harrow  attached  to  a  heavy  chain. 
In  both  cases  tlie  agitation  of  the  water  seems  to  have  produced  a  favor- 
able result.  The  pacha  succeeded  in  maintaining  a  channel  of  about  13 
feet  deep  through  the  Soulina  bar,  where  formerly  it  was  not  above  half 
this  depth.  By  the  same  plan  the  American  engineers  obtained  nearly 
20  feet  of  water  in  the  southwest  channel.  In  a  similar  way,  in  order  to 
force  the  torrents  to  deepen  their  beds,  the  inhabitants  of  the  Piedmontese 
Alps  used  to  plow  up  the  tracts  of  pebbles  which  were  brought  down  by 
the  floods.* 

Unfortunately,  this  simple  method  of  improving  the  condition  of  the 
bar  produces  no  lasting  result,  and  the  work  always  has  to  be  begun  over 
again  ;  for  the  bank  forms  again  whenever  the  drags  allow  a  moment's  res- 
pite to  the  sediment  held  in  suspension  by  the  water.  Besides,  when  the 
water  is  low  in  the  river,  the  operations  must  be  suspended,  or  the  sea 
would  drive  back  all  the  sediment  in  an-  up-stream  direction,  and  thus 
contribute  to  the  silting  up  of  the  river-bed.  It  must  also  be  remarked 
that  measures  of  this  kind  are  only  practicable  in  rivers  where  the  bar  is 
composed  of  small  particles,  and  is  not  subject  to  all  the  fury  of  the  wind 
and  the  billows.  At  the  mouth  of  the  Adour,  for  instance,  what  immense 
harrows  it  would  be  necessary  to  use  to  move  the  beds  of  shingle  driven 
up  by  the  storms ! 

A  system  of  moles  and  jetties  is,  therefore,  the  plan  that  has  generally 
been  resorted  to  by  engineers  in  the  improvement  of  the  mouths  of  riv- 
ere.  This  plan  is  somewhat  similar  to  that  of  the  embankments  which 
have  been  employed,  with  various  degrees  of  success,  on  the  middle 
courses  of  rivers ;  but  the  marine  dikes  have  not  always  produced  favor- 
able results,  and  a  great  many  experiments  which  seemed  to  offer  good 
chances  of  success  have  entirely  failed.  Among  the  undertakings  of  this 
kind  which  have  been  the  most  costly  and  the  most  useless,  we  may  men- 
tion those  which  have  been  carried  out  in  the  delta  of  the  Rhone.  It  was 
hoped  that,  by  confining  the  mass  of  water  in  a  narrower  channel,  and 
compelling  it  to  run  into  the  sea  through  a  single  outlet,  a  current  would 
be  produced  which  would  be  strong  enough  to  clear  out  the  passage  to  a 
considerable  depth,  and  thus  to  allow  ships  of  a  deep  draught  of  water  to 
enter  the  river.  In  1852,  Surell,  the  engineer,  closed  up  the  various 
graiis\  through  which  the  water  of  the  Rhone  found  lateral  outlets,  and 
lengthened  the  two  banks  of  the  principal  mouth  by  means  of  dikes  con- 
verging one  upon  another,  thus  doubling  the  force  of  the  current.  The 
water  of  the  river  did,  in  fact,  accomplish  the  work  of  erosion,  and  cleared 
out  the  channel ;  but  fresh  alluvium  being  incessantly  brought  down  by 
the  flow  of  the  Rhone,  and  thrown  up  by  the  waves  of  the  sea,  a  new  bar 

*  Chabrol,  Statistique  du  iMpartenient  fie  Montenotte. 

t  From  the  Latin  yradus,  a  step,  passage.  In  the  south  of  France  this  nnme  is  given  to 
the  outlets  of  rivers,  which  connect  the  shore  lakes  with  the  sea  and  the  mountain  defiles. 


358  '^^^  EARTH. 

formed  across  the  mouth  outside.  Before  the  operations  of  banking  were 
begun,  the  average  depth  of  the  channel  was  5  feet  10  inches;  at  the  pres- 
ent time  it  is  the  same,  after  having  varied  from  13  feet  to  6^  feet,  and 
3  feet  8  inches,  accoi'ding  to  the  quantity  of  water  sent  down  by  the 
current.* 

A  similar  undertaking,  attempted  in  1857,  in  the  southwest  channel  of 
the  Mississippi,  had  not  a  more  favorable  result,  a  curvilineal  jetty  1849 
yards  in  length  having  been  carried  away  by  a  tempest.  However,  the 
commissioner  appointed  by  the  federal  government  to  study  the  course 
of  action  of  the  delta  of  the  Mississippi  recommended  the  reconstruction 
of  convergent  jetties  as  being  a  plan  which  was  likely  to  keep  the  chan- 
nel clear.  Looking  forward  to  the  constant  increase  of  the  alluvium  of 
the  river  in  the  now  contracted  channel,  they  advised,  besides,  as  an  indis- 
pensable matter,  that  the  jetties  should  be  lengthened  about  245  yards 
every  year,  leaving  it  open  to  abandon  a  channel  and  choose  a  fresh  one 
when  the  dikes  of  the  first  outlet  should  have  attained  any  immoderate 
length.f  These  operations  would  be  enormous  in  their  character;  but  if, 
as  was  hoped,  they  would  result  in  maintaining  a  depth  of  more  than  19 
feet  in  the  channel,  a  tax  might  be  imposed  every  year  on  the  immense 
commerce  of  the  Lower  Mississippi  which  would  be  amply  sufficient  to  de- 
fray the  costs  of  construction. 

The  Adour,  which  does  not  carry  down  to  its  mouth  such  lai*ge  quanti- 
ties of  alluvium  as  the  Rhone  and  the  Mississippi,  is  one  of  those  few  riv- 
ers where  engineers  have  obtained,  at  least  temporarily,  favorable  results. 
Besides,  it  must  be  confessed  that  the  works  undertaken  for  the  improve- 
ment of  the  bar  have  lasted  for  a  good  many  years;  for  it  was  in  1694 
that  Ferry,  the  engineer,  constructed  at  the  southern  point  a  jetty  which 
was  to  fix  and  deepen  the  channel,  and  since  this  date  there  has  been  no 
cessation  in  this  interminable  labor.  The  lateral  dikes  have  been  carried 
on  to  the  sea,  either  in«rock-work  or  by  means  of  piles,  and  tending  in  va- 
rious directions,  which  were  adopted,  in  despair,  after  each  successive  fail- 
ure. Finally,  from  1855  to  1860,  the  jetties  of  the  two  points  were  slight- 
ly bent  round  to  the  north,  and  continued,  to  an  equal  distance  into  the 
sea,  to  a  point  550  yards  from  the  shore.  The  northern  jetty,  resting  upon 
a  base  of  rocks  hidden  under  the  water,  is  constructed  with  openings  along 
all  its  length,  and  allows  the  current  to  flow  between  the  piles.  The 
southern  jetty,  which  was  to  prevent  the  mouth  from  bending  round  to 
the  south,  is  solid  for  a  length  of  220  yards,  and  keeps  the  bar  tending  in 
a  direction  leading  to  the  coast.  Since  these  operations  were  finished,  the 
condition  of  the  river-mouth  has  been  subject  to  much  change.  In  Febru- 
ary, 1 862,  when  the  level  of  the  water  was  very  low,  a  bank  of  sand  form- 
ed exactly  across  the  mouth,  and  compelled  the  water  of  the  Adour  to  es- 
cape laterally  through  the  openings  between  the  dikes.  Nevertheless,  the 
general  state  of  the  channel  exhibits  a  considerable  improvement.     The 

*  Minard,  Des  Embouchures  des  Rivieres  Navigable^. 

t  Humphreys  and  Abbot,  Report  on  the  Mississippi  River. 


SABS  OF  RIVERS.  369 

cliaunel  has  taken  a  fixed  direction  toward  the  west,  and  no  longer  spreads 
out  to  the  south ; -the  bar  has  been  driven  far  out  to  sea,  but  the  average 
Uepth  of  water  oh  it  is  greater.  Before  the  improvements  were  begun,  at 
low  water  it  was  covered  with  only  5  feet  to  5  feet  10  inches  of  water; 
the  depth  is  now  as  much  as  10^  feet.  This  is  an  immense  result,  which, 
according  to  the  calculations  of  an  author  who  is  sufficiently  skeptical  in 
matters  of  this  kind,*  represents  a  clear  annual  gain  of  forty  thousand 
pounds  for  the  commerce  of  Bayonne.  If,  in  the  future,  the  bank  of  shin- 
gle should  attain  to  the  same  height  as  before,  it  would  be  necessary  to 
again  lengthen  the  jetties  of  the  Adour  for  several  hundred  yards  into  the 
gulf,  and,  by  means  of  the  experience  already  acquired,  the  engineering 
operations  woflld  again  produce  a  considerable  temporary  improvement. 
According  to  M.  Bouquet  de  la  Grye,  whose  opinion  is  a  very  valuable 
one,  it  would  be  a  very  useful  measure  if  the  barriers  were  curved  round 
in  a  southwesterly  direction,  so  that  the  waves  from  the  offing  should  not 
beat  directly  in  front  of  the  current  and  ebbing  tide.  But  the  chances  in 
favor  of  any  decisive  amelioration  of  the  bar  must  be  much  increased  in 
proj)ortion  as  the  jetties  are  lengthened.  When  these  artificial  promon- 
tories, like  headlands,  are  surrounded  by  a  deep  sea,  the  debris  which  the 
currents  and  waves  deposit  at  their  base  will  be  no  longer  incessantly  agi- 
tated by  the  breakers,  and  thus  raised  into  the  form  of  a  bar ;  they  will 
accumulate  but  slowly,  and  a  long  series  of  years,  or  even  centuries,  must 
elapse  ere  they  could  seriously  jnodify  the  submarine  features.f 

The  operations  undertaken  at  Soulina — one  of  the  mouths  of  the  Dan- 
ube— appear  to  have  met  with  great  success,  but  through  an  entirely 
special  cause.  Mr.  Charles  Hartley,  the  skillful  constructor  of  the  Soulina 
jetties,  has  taken  care  to  push  them  out  more  than  a  hundred  yards  into 
the  sea,  as  far  as  a  point  where  a  current  generally  passes  along  the  shore 
tending  from  north  to  south.  This  current  catches  hold  of  all  the  alluvi- 
um which  glides  down  over  the  bottom  of  the  bed  of  the  river,  and  thus 
hinders  the  formation  of  a  fresh  bar.|  The  average  depth  of  the  channel, 
which  was  only  9  feet  before  the  commencement  of  the  works,  is  now 
not  less  than  16^  feet  since  the  dikes  have  been  constructed.  It  is  cer- 
tainly a  fact  that  the  gradual  encroachments  of  the  whole  delta  of  the 
Danube  will  have  the  effect  of  pushing  the  current  itself  farther  out  to 
sea,  and  sooner  or  later  a  second  mound  of  sand  will  obstruct  the  mouth 
of  the  Soulina.  According  to  an  approximate  calculation,  based,  liowev- 
er,  on  plenty  of  hypotheses,  the  works  finished  in  1860  will  not  become 
completely  useless  until  the  year  1916.§ 

There  are  other  mouths  of  rivers,  espec^Uy  those  of  the  Oder  in  Prus- 
sia, and  the  MeUse  in  Holland,  which  have  been  permanently  improved 
by  engineering  operations ;  we  are  not,  therefore,  entirely  warranted  in 

*  Minard,  Des  Embouchures  des  Rivieres  Navigablea. 

+  Mongel-Bey,  Percement  de  risfhme  de  Suez. 

X  Zeilschrift  fur  Allyemeine  Erdkunde. 

§  Engelbardt,  Etudes  sur  les  Embouchures  du  Danube. 

Aa 


370 


THE  EARTH. 


ifM 


Fig.  146.  Months  of  the  Danube.    Arms  of  Kilia  an4  Sonlina. 

repeating  the  words  of  Vauban,  and  characterizing  all  the  bars  of  naviga- 
ble rivers  as  "  incorrigible."  The  results  obtained  on  the  Clyde,  in  Scot- 
land, may  especially  be  classed  among  the  most  important  triumphs  of 
engineering  art.  The  water  qf  that  river  was  once  so  very  shallow  that 
ships  of  a  deep  draught  of  water  were  compelled  to  stop  15-^  miles  below 
Glasgow,  and  the  merchandise  had  to  be  reshipped  in  barges ;  at  the  pres- 
ent time  great  three-masters  easily  come  up  close  to  the  quays.  Besides, 
in  a  great  many  cases  it  might,  perhaps,  be  possible  to  divert  the  mouth 
of  a  river  in  places  where  it  was  not  possible  to  force  a  passage,  and  thus, 
by  indirect  means,  to  obtain  the  depth  of  water  necessary  for  large  ships. 


BAItS  OF  RIVERS. 


371 


^  i 

^      I 
-9    ; 


Fig.  147.  Jetties  of  Soulina. 

A  deep  canal,  protected  against  alluvium  by  a  system  of  sluices,  would 
then  replace  the  natural  channel.  This  plan,  according  to  M.  Desjardins, 
is  that  which  was  adopted  by  the  ancients  in  the  case  of  the  Tiber  and 
the  western  branch  of  the  Nile,  which  was  diverted  toward  Alexandria. 
This  plan,  too,  has  been  proposed  by  several  American  engineers  for  insur- 
ing to  New  Orleans  a  magnificent  port  worthy  of  the  river  which  bathes 
its  quays.  Moreover,  a  work  of  this  kind  is  being  carried  out  at  the 
mouth  of  the  Rhone  by  the  digging  out  of  the  canal  of  St.  Louis.  This 
navigable  channel  is  2^  miles  long  and  66  yards  wide,  and  is  intended  to 
connect  the  river  with  the  Gulf  of  Fos — so  called  from  a  former  navigable 
canal  dug  out  by  Marius  {fossce  mariance).  Vessels  drawing  24  feet  of 
water  will  thus  be  able  to  ascend  as  far  as  the  port  of  Aries,  which  at  the 
present  day  has  been  almost  abandoned  by  commerce,  on  account  of  the 
deficiency  of  water  in  the  channels  of  the  Rhone.  If  the  excavation  of 
the  canal  of  St.  Louis  meets  with  success — which  scarcely  seems  a  doubt- 
ful point — this  great  undertaking  will  serve  as  a  model  for  the  subjection 
of  other  mouths  of  rivers,  which,  up  to  the  present  time,  have  continued 
rebellious  to  the  operations  of  engineei*s.' 


372  THE  EARTH. 


CHAPTER  LV. 

ALTERATION    IN    THE    POSITION    OF    WATER -COURSES    IN    CONSEQUENCE    OF 

THE    ROTATION   OF  THE   EARTH. MASSES   OF   WATER  BROUGHT  DOWN  TO 

THE   SEA  BY   RIVERS. — GENERAL   CONSIDERATIONS. 

The  sudden  changes  in  river-beds  produced  by  the  rupture  of  their 
dikes,  as  well  as  the  movements,  and  even  obliterations  of  their  mouths, 
constitute,  generally  speaking,  catastrophes  of  a  serious  character,  and  it 
may  readily  be  conceived  that  the  imagination  of  man  has  looked  upon 
these  incidents  as  among  the  most  important  facts  in  the  history  of  rivers. 
Yet  this  is  not  the  case.  However  great  may  be  the  influence  of  these 
sudden  modifications  in  the  action  of  water-courses,  they  are  but  phenom- 
ena of  a  secondary  class  in  comparison  with  those  more  durable  changes 
which  the  rotation  of  the  earth  brings  into  the  economy  of  every  river 
and  the  general  physiognomy  of  its  basin.  The  fact  is,  that  the  water  of 
rivers,  like  that  of  the  ocean  and  the  aerial  waveS,  is  subject  to  the  influ- 
ence of  all  the  great  astronomical  laws.  Rivers,  as  well  as  the  winds, 
have  a  natural  tendency  to  shift  their  course,  so  as  to  effect  an  arc  of  rev- 
olution round  the  planet. 

In  fact,  the  running  water  which  th6  earth  carries  round  in  its  diurnal 
movement  is  affected  differently  from  the  solid  bodies  which  lie  upon  the 
ground.  While  the  latter,  just  as  the  mere  inequalities  in  the  terrestrial 
surface,  describe  their  daily  orbit  round  the  central  axis,  the  fluid  parti- 
cles which  glide  over  the  rotundity  of  the  globe  traverse  in  succession 
various  latitudes,  and  their  movement  consequently  varies.  The  speed  of 
rotation  being  completely  nullified  at  the  mathematical  points  which  act 
as  poles,  and  increasing  gradually  as  far  as  the  equatorial  regions,  where 
it  exceeds  1470  feet  a  second,  every  thing  movable  which  tends  from  one 
of  the  poles  to  the  equator  must  necessarily  remain  in  the  rear  of  the  in- 
creasingly rapid  terrestrial  movement  which  carries  it  round,  and  must 
consequently  deviate  toward  the  west — that  is,  to  the  right  hand  in  the 
northern  hemisphere,  and  to  the  left  in  the  southern.  In  like  manner,  any 
movable  body  which  takes  its  course  from  the  equator  to  one  of  the  poles 
exceeds — owing  to  its  acquired  speed — the  angular  movement  of  the  globe, 
and  inevitably  deviates  to  the  east ;  that  is,  to  the  right  in  the  northern 
hemisphere,  and  to  the  left  in  the  southern.  These  facts  have  been  ren- 
dered perceptible  by  the  celebrated  experiments  of  M.  Foucault  on  the 
pendulum  of  the  Pantheon;  and  they  can  easily  be  verified  by  every  one 
by  causing  the  rotation  of  two  suspended  globes,  and  by  allowing  some 
colored  liquid  to  glide  over  their  surfaces.*  The  trade  winds  and  all  at- 
*  A.  Herschel,  Intellectual  Observer,  November,  1865. 


DIRECTION  OF  RIVES-  CO  URSES.  373 

mospheric  currents  obey  this  law  of  deviation,  as  well  as  the  Guli  Stream 
and  the  other  flows  of  the  ocean.  Even  balls  rushing  from  the  mouth  of 
a  cannon  are  subject  to  this  law ;  and  sometimes  the  locomotives  on  our 
railroads,  when  they  run  off  the  lines.  This  law  applies  equally  to  all 
water-courses,  and — provided  that  the  configuration  of  the  ground  allows 
it,  and  that  the  oscillations  of  the  terrestrial  surface  do  not  hinder  it — it 
causes  running  water  to  deviate  regularly  to  the  right  in  the  northern 
hemisphere,  and  to  the  left  in  the  southern.  With  regard  to  those  rivers 
which  flow  in  a  line  parallel  to  the  equator,  there  is  no  force  which  com- 
pels them  to  eat  away  either  one  or  the  other  of  their  banks ;  but  they 
are  retarded  in  their  course  if  they  flow  to  the  east,  and  are,  on  the  con- 
trary, accelerated  if  they  run  toward  the  west. 

This  is  the  law  which,  for  some  time  past,  several  geographers  have 
pointed  out;  which,  however,  M.de  Baer  has  had  the  honor  of  completely 
bringing  to  light.  The  only  difficulty  is  to  make  a  choice  among  the  nu- 
merous rivers  which  may  be  mentioned  as  examples  of  water-courses  mod- 
ifying their  course  in  the  direction  presupposed  by  this  theory.  South  of 
the  equator  there  are  the  affluents  of  the  gigantic  Rio  de  la  Plata,  which, 
after  having  watered  on  the  west  the  extent  o^  the  pampas^  are  incessantly 
wearing  away  their  left  banks.  In  the  northern  hemisphere  there  is  the 
Euphrates,  which  endeavors  to  pour  itself  bodily  into  the  bed  of  the  Hin- 
diah,  to  the  right  of  its  own  course  ;*  there  is  also  the  Ganges,  which  aban- 
dons the  town  of  Gour,  in  the  midst  of  the  jungles,  and  shifts  in  its  delta 
four  or  five  miles  to  the  west.f  There  is  the  Indus,  wearing  away  the 
stony  hills  of  its  western  bank,  so  as  to  move  its  delta  for  more  than  600 
miles  in  that  direction.  There  is  the  Nile,  leaving  its  ancient  bed  in  the 
Libyan  desert,  in  order  to  carry  its  waters  by  the  side  of  the  Arabian 
chain  of  mountains.  In  like  manner,  in  Europe,  the  Gironde,  the  Loire, 
and  the  Elbe  wear  away  the  escarpments  of  their  right  bank ;  and  the 
Vistula  deepens  its  eastern  mouth  at  the  expense  of  that  to  the  left.  The 
Rhine,  in  the  plains  of  Alsace,  is  gradually  increasing  its  distance  from  the 
base  of  the  Vosges,  and  is  approaching  the  mountains  of  the  Black  Forest ; 
and  so  long  as  its  course  was  not  fixed  by  the  continuous  rampart  of  its 
embankments,  it  constantly  gained  on  the  territory  of  Baden,  and  bent 
round  to  the  west  of  the  hills,  along  the  foot  of  which  it  had  previously 
flowed.^  A  still  more  remarkable  fact  is  exemplified  by  the  Danube, 
which  passes  in  succession  through  a  series  of  defiles,  and  always  develops 
its  windings  toward  the  right  below  each  gate  of  rocks  through  which  it 
has  to  pass.  The  river  shifts  its  place  under  the  influence  of  the  move- 
ment of  terrestrial  rotation  in  the  same  way  that  a  cord  fastened  at  cer- 
tain points  would  bend  under  the  influence  of  a  current.§  Thus,  when 
entering  the  plains  of  Hungary,  which  were  once  a  vast  lake,  the  Danube, 

*  Mittheiluntjen  von  Pc<i»r»innn,  vol.  xi..  1862. 
t  Fergtison,  Zeitxrhrift  fur  Erdkunde.  April,  1 864. 
X  Bonrlot.  Variations  de.  lAilifufle  et  de  Climat. 
§  Von  Siiss,  Der  Boden  der  Sladt  IVien. 


374 


THE  EARTH. 


instead  oi  crossing  diagonally  the  level  tract  bathed  by  its  waters,  bends 
suddenly  to  the  south,  and  then  to  the  east,  so  as  to  take  the  course  of  the 
great  central  depression  round  the  high  ground  on  its  right. 

In  European  and  Asiatic  Russia  the  normal  displacement  of  rivers  affords 
an  especial  opportunity  for  most  interesting  studies.     In  these  countries, 


Fig.  14&  Middle  Coarse  of  the  Volga. 


in  fact,  all  those  conditions  are  united  which  are  most  favorable  to  the 
gradual  encroachment  of  the  rivers  on  their  right  banks ;  they  have  a 
very  considerable  length  of  course,  and  the  liquid  masses  are  powerful 
enough  to  readily  clear  away  any  obstacles;  there  are  enonnous  floods 
which  periodically  increase  the  force  of  erosion  in  the  currents,  and  the 


DIRECTION  OF  RIVER-  CO  URSES.  375 

• 
olitFs  are  composed  of  friable  rocks ;  lastly,  the  sharp  curvature  of  the 
globe  is  the  cause  of  a  rapid  change  in  the  speed  of  rotation  in  the  vari- 
ous latitudes.  Two  centuries  ago,  the  principal  mouth  of  the  Volga  flowed 
directly  to  the  east  of  Astrakhan;  since  that  time  the  great  current  has 
successively  hollowed  out  for  itself  fresh  beds,  tending  more  and  more  to 
the  right ;  and  at  the  present  day  the  branch  navigated  by  vessels  turns 
to  the  south-southwest.  Above  the  delta  the  river  has  every  where  shifted 
its  bed  toward  the  west,  and  opposite  Tchernoi-Iar,  the  Achtouba,  the 
former  bed  of  the  Volga,  now  lies  12^  miles  from  the  principal  current. 
The  twenty-three  towns  which  have  been  built  on  the  western  bank,  also 
called  the  upper  bank  on  account  of  its  high  cliflfs,  have  been  almost  all 
demolished  in  detail,  house  by  house,  and  street  by  street,  and,  being  thus 
undermined  on  one  side,  they  have  been  compelled  to  advance  on  the  other 
into  steppe-land.  On  the  east,  the  plains  once  washed  by  the  river  are 
scarcely  raised  above  the  average  level  of  the  water :  during  inundations 
they  are  converted  into  perfect  seas ;  therefore  the  people  have  not  been 
able  to  build  more  than  three  towns  on  the  eastern  bank.  One  of  these 
towns — Kasan — was  once  situated  at  the  confluence  of  the  Kasanka  and 
the  Volga,  but  is  now  two  miles  from  the  latter  river ;  it  has,  so  to  speak, 
traveled  to  the  east.  In  Siberia  the  water-courses  move  to  the  right  still 
more  rapidly.  The  modern  towns  of  Yakutsk,  Tobolsk,  Semipalatinsk, 
and  Xarym  have  already  been  partially  rebuilt.  Along  these  water- 
courses, the  right  bank,  which  is  undermined  by  the  current,  is  almost  in- 
variably higher  than  the  left  bank  bordering  on  the  tovndras,  which  once 
served  as  the  bed  of  the  river.  This  is  a  fact  of  such  a  general  nature 
that  map-designers  admit  it  as  an  axiom,  and  never  fail  to  draw  the  right 
bank  as  being  the  highest  and  the  most  escarped. 

A  large  number  of  rapids  and  cataracts — among  others,  the  magnificent 
falls  of  Trolhata — also  afford  examples  of  a  continuous  displacement  jjro- 
duced  by  the  rotation  of  the  globe.  Similar  phenomena  arc  likewise  ob- 
served in  those  river-like  arms  of  the  sea  which  are  formed  by  the  sea- 
water  passing  through  a  narrow  channel ;  thus  the  force  of  the  current 
is  exercised  mostly  on  the  right-hand  side  in  the  Straits  of  Kertch  and 


Fig.  14'.),  Lcfi  and  Hight  Uiver-banks. 

the  Bosphorus,  and  the  greatest  amount  of  erosion  takes  place  on  this 
side.  The  law  is  of  general  effect,  and  applies  to  all  the  rivers  which  flow 
on  the  surface  of  the  earth.  The  great  rushes  of  water  in  former  geolog- 
ical periods  have  likewise  in  their  flow  worn  away  the  ground  on  the 


376 


THE  EARTH. 


right-hand  side.  In  the  north  of  the  Pyrenees,  the  gaves^  which  radiate 
so  remarkably  round  the  plateaux  of  Louvdes  and  Lannemezan,  all  flow- 
through  valleys  of  erosion,  commanded  on  the  east  by  high  clifis  worn 
away  at  their  base,  and  on  the  west  by  long  slopes  of  easy  access,  on 
which  the  debris  are  deposited.* 


Fig.  150.  Radiation  of  the  " Gaves,"  Noiih  Pyrenees. 


Among  the  important  rivers  which,  in  consequence  of  local  circum- 
stances, seem  to  contradict  this  law  of  the  displacement  of  running  water, 
we  may  mention  the  Mississippi  and  the  Rhone.  Instead  of  gaining  on  its 
right  bank,  and  eroding  the  base  of  the  heights  which  rise  on  the  west, 
the  great  American  river  impinges  in  fifteen  places  against  the  cliffs  of 
the  eastern  plateau,  and,  throughout  the  whole  of  its  course,  constantly 
tends  toward  the  left.  As  soon  as  it  enters  the  marshy  plain  of  its  delta 
at  a  point  below  Baton  Rouge,  it  flows  almost  in  a  straight  line  toward 
the  southeast,  to  form  the  remarkable  peninsula  of  mud  through  which  it 
falls  into  the  sea.  It  must  be  remarked  that  the  direction  taken  by  the 
water  of  the  current  of  the  Mississippi  is  exactly  the  same  as  that  of  all 
the  rivers  which  run  into  the  Gulf  of  Mexico — the  Rio  Grande  and  its  af- 
fluents,  the  Rio  Pecos,  the  Nueces,  the  Colorado  of  Texas,  the  Brazos,  the 

*  Levmerie. 


DIRECTION  OF  RIVER-COURSES.  377 

Tiiuity,  the  Neches :  these  rivers,  which  uniformly  tend  toward  the  south- 
east, are  parallel  to  the  ridges  of  the  Rocky  Mountains.  If  it  is  a  fact, 
as  many  geologists  seem  to  have  established,  that  the  western  chains  of 
North  America  are  undergoing  a  movement  of  upheaval,  while  the  Caro- 
linas,  Georgia,  and  other  neighboring  regions  are  gradually  subsiding,  it 
might  vjery  well  be  the  case  that  the  lower  course  of  the  Mississippi  and 
all  the  Texan  rivers  tends  to  the  east,  in  consequence  of  the  slow  move- 
ments of  elevation  and  depression  to  which  the  North  American  continent 
is  subjected.* 

With  regard  to  the  Rhone,  the  mouth  of  which  likewise  flows  in  a  south- 
east direction,  instead  of  tending  to  the  right,  as  it  once  did,  and  follow- 
ing the  vast  bed  now  adopted  by  the  smaller  Rhone,  it  is  possible  that  its 
course  may  have  been  modified  during  historic  periods  by  the  impetuosity 
of  the  Mistral.  However  strange  an  assertion  of  this  kind  may  appear 
at  first  sight,  it  perhaps  merits  the  attention  of  geographers.  In  fact,  it 
seems  a  matter  beyond  all  doubt  that,  in  consequence  of  the  gradual  cut- 
ting down  of  the  woods  of  the  Cevennes  and  the  central  plateau  of  France, 
the  Mistral  has  continued  to  increase  in  violence  since  the  ages  of  the  Ro- 
man occupation.  If  this  be  so,  this  turbulent  wind  must  necessarily  impel 
the  waters  of  the  Rhone  toward  the  left  bank  in  the  direction  they  are 
taking  at  the  present  day.  The  aerial  current  beating  down  from  the 
Cevennes  on  the  marshes  of  the  Camargue  must  necessarily  have  pressed 
upon  the  current  of  the  river,  and  marked  out  for  it  the  line  which  it  had 
to  follow  in  hollowing  out  for  itself  a  fresh  bed.  Every  thing  in  nature 
takes  its  share  in  effecting  modifications ;  every  feature  in  the  planet  owes 
its  form  to  the  breath  of  the  winds,  the  currents  of  the  waters,  and  the 
movements  of  the  soil,  quite  as  much  as  to  the  motion  of  the  globe  in  space. 

Rivers,  taken  as  a  whole,  being  merely  the  arterial  system  of  continents, 
renewing  the  liquid  mass  of  the  seas,  whence  the  waters  return  again  to 
the  interior  of  the  land  in  the  form  of  clouds  and  rain,  it  is  important  to 
know,  at  least  approximately,  the  quantity  of  river-water  which  is  flowing 
on  the  surface  of  the  globe.  For  many  years  back,  various  hypotljpsea 
have  been  regarded  on  this  point;  but  any  very  precise  data  are  still 
wanting,  and  nothing  but  observations  taken  for  a  series  of  years  will 
render  it  possible  to  arrive  at  any  accurate  knowledge  of  this  hydrologic- 
al  fact,  so  important  in  the  economy  of  the  globe.  Buflbn  supposed  that 
the  mass  of  water  emptied  out  by  the  whole  of  the  rivers  running  into  the 
sea  would  represent,  in  812  years,  a  quantity  of  water  equal  to  that  of  the 
ocean ;  but  the  data  on  which  he  based  his  supposition  are  not  of  sufficient 
authority  to  render  it  of  much  use  to  discuss  his  opinion  at  the  present  day. 
Among  the  most  important  calculations  which  have  been  recently  made, 
taking  as  thrir  starting-point  the  quantity  of  rain  falling  annually  on  the 
earth,  we  must  mention  that  of  Metcalfe.  He  estimates  the  total  mass  of 
water  brought  down  by  the  rivers  at  176,000,000,000  of  cubic  yards  of 
water  every  day.  Keith  Johnston  considers  that  the  daily  average  dis- 
*  Vide  the  chapter  on  "  Upheavals  and  Depressions." 


378  ^-S^  EARTH. 

charge  of  the  rivers  of  the  earth  is  229,000,000,000  of  cubic  yards,  or 
more  than  2.620,000  cubic  yards  a  second. 

This  estimate  is  certainly  much  too  high,  for,  by  adopting  another  meth- 
od, more  in  conformity  to  the  rules  of  direct  observation,  and  consequently 
more  scientific — that  is,  by  adding  up  the  masses  of  water  rolled  down  by 
the  rivers  which  have  been  already  gauged  in  various  parts  of  the  world 
by  engineers  and  geographers — we  find  that  the  total  discharge  of  a  col- 
lection of  river-basins  comprehending  an  area  of  4,246,000  square  miles 
does  not  exceed  a  little  more  than  72,000  cubic  yards  a  second.  Now 
these  basins,  which  are  those  of  the  principal  rivers  of  Western  Europe, 
including  the  Danube,*  as  well  as  those  of  the  Nile,  the  Chat-el-Arab,  the 
Ganges,  the  Hoangho,  the  Mississippi,  and  the  Atrato,  form  a  tenth  part 


§       ^  t  III 

i    i        i        S    I    I 


hi 


Pig-.  151.  Diagram  shomng  the  Comparative  Discharge  of  Rivers,  in  Cubic  Yards. 

of  the  terrestrial  surface,  the  waters  of  which  flow  down  to  the  ocean. 
If,  therefore,  the  proportion  of  water  which  runs  from  the  surface  of  the 
ground  into  the  sea  were  every  where  the  same,  the  liquid  mass  of  fresh 
water  combining  with  the  salt  waves  would  not  be  more  than  850,000 
cubic  yards  a  second.  We  must,  however,  take  into  account  the  enor- 
mous quantity  of  water  discharged  by  certain  rivers  in  the  tropical  zone, 
and  especially  the  Amazon,  the  delivery  of  which  is  probably  100,000  to 
130,000  cubic  yards.f  If,  therefore,  we  add  a  third  to  the  total  river-dis- 
charge obtained  by  the  previous  calculations,  we  shall  have  for  the  whole 
mass  a  maximum  of  over  1,100,000  cubic  yards  a  second.  This  is  a  quanti- 
ty which  represents  an  average  fall  of  about  1 1  inches  of  rain  over  the  en- 
tire surface  of  each  basin,  an  average  much  larger  than  that  of  most  of  the 
rivers  which  have  been  studied  up  to  the  present  time.  If  we  admit  that 
the  average  depth  of  the  seas  is  5400  yards,  the  quantity  of  water  which 
flows  down  the  surface  rivers  of  the  Continent  would  not  equal  that  which 
fills  up  the  abysses  of  the  ocean  until  after  a  lapse  of  fifty  millions  of  years. 
This  is  evidently  nothing  but  a  provisional  calculation,  which  will  be 
gradually  rectified  as  the  facts  relative  to  the  hydrology  of  the  globe  be- 

*  The  discharge  attrihated  to  the  Danube  is  probably  too  great ;  according  to  M.  Hartley, 
the  real  discharge  is  only  11,123  cubic  yards  a  second. 

t  At  the  defile  of  Obydos,  the  section  of  water  which  flows  every  second  to  the  sea  is,  ac- 
cording to  Spix  and  Martius,  23,113  cubic  yards  at  low-water  time ;  in  floods,  says  Ave-Lal- 
lemant,  it  is  319,476  yards  at  the  same  spot. 


SEDIMENT  OF  RIVERS.  379 

come  better  known.  When  the  mean  discharge  of  all  visible  water- 
courses is  accurately  gauged,  when  the  force  of  subterranean  streams  has 
been  disclosed  by  the  investigations  of  meteorologists  as  to  the  fall  and 
evaporation  of  rain,  then  it  will  be  more  easy  to  calculate,  within  a  few 
millions,  the  total  mass  of  liquid  which  is  annually  poured  into  the  sea  by 
the  rivers  of  the  continents.  No  doubt,  within  a  period  not  very  distant, 
the  measures  which  have  been  adopted  with  so  much  precision  as  regards 
the  Mississippi,  the  Po,  the  Rhone,  and  the  Nile,  will  be  applied  with  equal 
care  to  the  other  river-mouths. 

The  investigations  which  have  been  simultaneously  made  as  to  the  pro- 
portion of  sediment  which  exists  in  suspension  in  rivers  will  enable  us  also 
to  resolve  the  often-discussed  question  as  to  the  actual  importance  of  the 
alluvium  of  rivers.  Without  mentioning  here  the  streams  which  are  lit- 
erally liquid  mud,  or  sometimes  even  avalanches  of  mud,  there  are  some 
rivers,  like  the  Missouri,  the  waters  of  which  are  so  charged  with  sediment 
that  the  drift-wood,  being  completely  penetrated  with  muddy  particles,  is 
ultimately  entirely  submerged,  and  covers  the  bottom  of  the  river.*  There 
are,  on  the  contrary,  other  rivers,  such  as  the  St.  Lawrence,  which  send 
down  to  the  ocean  water  which  is  generally  pure  and  transparent.  Dur- 
ing floods  the  Durance  holds  in  suspension  as  much  as  21  thousandths  of 
mud;f  the  Garonne  sometimes  contains  10  thousandths  ;J;  the  Rhine  6 
thousandths  only.§  It  will  be  readily  understood  that  the  quantity  of 
alluvium  held  in  suspension  must  necessarily  vary  in  different  rivers,  ac- 
cording to  the  more  or  less  compact  nature  of  the  soils  through  which  they 
pass ;  thus  observations  made  on  any  particular  water-course  have  noth- 
ing more  than  a  local  value.  The  estimations  made  by  various  geogra- 
phers as  to  the  average  quantity  of  alluvium  contained  in  running  water 
differ  prodigiously  one  from  another.  In  the  last  century,  Eustache  Man- 
fredi,  who,  taking  account  of  the  enormous  deposits  produced  by  the  Po, 
exaggerated  the  work  of  this  kind  accomplished  by  other  rivers,  and  esti- 
mated the  average  proportion  of  muddy  matter  at  -j-fs  of  the  liquid  mass 
of  rivers.  But  in  this  estimate  he  doubtless  included  the  sand  and  mud 
which  are  impelled  by  the  cuiTent  along  the  bottom  of  the  bed,  the  bulk 
of  which  is  probably  twice  as  large  as  that  of  the  floating  matter.  Ilart- 
soeker,  in  his  Traite  de  Physique^  admitted  that  the  proportion  of  alluvi- 
um was  -rlrr »  while  another  author  of  the  same  epoch,  the  writer  of  the 
RecJierches  Philosophiques  sur  les  Americains,  was  led  by  his  observations 
and  calculations  to  fix  the  amounts  of  debris  existing  in  the  water  of  riv- 

<-^rs  at  TT.iwII 

Tlie  differences  between  the  various  estimates  are  naturally  quite  as 
great  when  an  endeavor  is  made  to  reckon  approximately  the  time  that  it 

•  Continental  Monthli/,  Jane,  ISGi. 

*■  Payen.     The  average  for  the  whole  of  the  year  is  not  more  than  one  thousandth. 

♦  Banmgarten.  §  Payen. 

II  This  question  is  treated  on  in  detail  in  Von  Hoff's  work,  Veranderungen  derErdoberJidche, 
vol.  i. 


380  ^^^  EARTH. 

would  take  for  the  alluvium  emptied  out  at  the  mouths  of  rivers  to  raise 
the  level  of  the  ocean  to  a  given  point.  Manfredi  supposes  that  the  de- 
tritus carried  down  to  the  sea  would  be  suflScient  to  raise  its  bed  a  yard 
in  3300  years.  Tyler  thinks  himself  warranted,  by  his  calculations  as  to 
the  alluvium  of  the  Mississippi,  in  asserting  that  the  deposits  of  rivers 
would  elevate  the  level  of  the  ocean  only  two  inches  in  10,000  years,  or 
about  a  yard  in  180,000  years.  These  are  estimates  of  a  very  different 
character ;  but  when  one  reflects  on  the  greatness  of  the  sea,  and  on  the  lit- 
tleness of  rivers  compared  with  the  immense  reservoir,  even  the  last-named 
estimate  seems  too  high.  If  we  admit  that  the  average  proportion  of  the 
earthy  matter  carried  down  into  the  sea  is  about  ;g-(nnr  of  the  entire  liquid 
mass  of  rivers,  and  if  we  adopt,  as  the  total  discharge  of  running  water,  the 
approximate  quantity  to  which  the  critical  examination  of  the  known  facts 
of  fluviatile  hydrography  has  led  us,  we  shall  find  that  the  mass  of  allu- 
vium deposited  every  second  at  the  mouths  of  rivers  would  be  equivalent 
in  bulk  to  436  cubic  yards,  or  every  year  a  body  of  matter  equal  to  4000 
square  miles  in  area,  and  a  yard  thick.  Tliis,  however,  would  be  an  al- 
most infinitesimal  quantity  in  comparison  with  the  enormous  abysses  of 
the  ocean. 

Yet  the  earth  belongs  to  all  time,  and  during  the  course  of  ages  any 
geological  work  must  ultimately  be  accomplished.  These  rivers,  almost 
imperceptible,  so  to  speak,  in  comparison  with  the  ocean,  are  gradually 
eating  away  mountains  and  plateaux,  and  filling  up  the  abysses  of  the  sea 
with  their  accumulated  debris.  These  deposits  have  the  efiect  of  raising 
the  average  level  of  the  waters  of  the  ocean,  and  of  causing  them  to  cover 
low  shores.  There  is,  therefore,  a  double  cause  operating  in  the  modifica- 
tion of  the  relief  and  outline  of  continental  masses.  If  the  only  force  in 
action  on  the  surface  of  the  globe  was  that  of  running  waters,  the  elevated 
parts  of  the  earth  would  be  constantly  becoming  lower,  the  sea  would  in- 
cessantly encroach  on  the  coasts,  and,  sooner  or  later,  the  planet  would 
become  an  immense  globe,  covered  with  a  thin  sheet  of  water.  Owing, 
however,  to  the  geological  movements  of  the  earth's  strata,  a  tiansforma- 
tion  of  this  kind  is  not  to  be  dreaded  ;  but  still,  from  the  action  of  the  wa- 
ter of  rivers,  continents  and  seas  are  undergoing  changes  of  the  very  high- 
est geographical  importance.  The  Baltic  Sea  has  already  become  some- 
thing between  an  inland  sea  and  a  chain  of  fresh-water  lakes.  The  liquid 
mass  poured  into  it  by  rivers  continues  always  the  same,  while  the  area 
and  depth  of  its  basin  are  constantly  diminishing.  In  the  long  course  of 
ages,  its  water  will  ultimately  become  perfectly  fresh,  and  the  straits  of 
the  Sound  will  be  only  the  European  St.  Lawrence. 

Some  day,  Bory  de  Saint  Vincent  tells  us,  the  Mediterranean  itself  will 
become  nothing  more  than  a  chain  of  lakes,  and  then  a  gigantic  river. 
The  Sea  of  Azof  is  already  being  gradually  converted  into  a  stream,  as  its 
shores  are  getting  nearer  and  nearer  together,  while  its  bed  remains  per- 
ceptibly the  same.*    The  tracts  of  water  which  extend  from  the  mouth 

*  Zeitschriftfiir  £rdkunde,  May,  1862. 


VALUE  OF  RIVERS.  3S1 

of  the  Don  to  the  Straits  of  the  Dardanelles  might  be  compared  to  the 
Lakes  Superior,  Huron,  and  Mich*gan ;  the  isles  of  the  Archipelago  will 
some  day  overlook  a  labyrinth  of  lagoons  similar  to  those  which  border 
the  Baltic  Sea;  the  Gulf  of  Venice  will  be  only  an  elongation  of  the  val- 
ley of  the  Po ;  and  the  two  great  basins  of  the  Mediterranean,  separated 
by  the  Siculo- African  bar,  will  become  two  lakes  of  increasingly  contract- 
ed dimensions,  the  waters  of  which  will  feed  the  greatest  river  in  4,he 
world.  Then  the  Dnieper,  the  Danube,  and  the  Po  will  be  but  mere  trib- 
utaries. Perhaps  even  the  Nile,  which  is  now  of  no  great  size  at  its  mouth, 
may  lose  all  its  water  by  means  of  evaporation  before  it  reaches  the  Med- 
iterranean Sea,  and  will  become  nothing  but  a  water-course  of  an  entirely 
continental  character,  such  as  the  Chary,  the  Houach,  and  the  Jordan. 

Certainly' it  would  be  difficult  to  exaggerate  the  importance  of  the  part 
played  by  rivers  in  the  history  both  of  the  earth  and  mankind.  They  dis- 
tribute uniformly  the  snow  and  rain  which  fall  at  the  various  points  of 
their  basins,  and  fertilize  the  whole  territories  by  their  innumerable  rami- 
tications.  They  powder  up  the  rocks  of  the  mountains,  and  spread  the 
matter  which  results  in  fertile  alluvium  over  the  plains,  forming  also  new 
tracts  of  land  at  their  mouths.  They  equalize  climates.  Rivers  coming 
from  the  south  warm  with  their  vapor  northern  districts,  while  rivers 
flowing  in  a  contrary  direction  moderate  the  heat  in  more  southera  lati- 
tudes. Added  to  this,  water-courses,  those  powerful  workers,  do  not  limit 
themselves  to  carrying  down  water,  alluvium,  and  climate  ;  they  also  roll 
down  in  their  flow  the  history  and  life  of  nations.  The  course  of  the  riv- 
er's current  is  the  path  down  which  descended  the  canoe  of  the  savage 
warrior,  and  is  now  the  highway  for  the  fleets  of  commerce  bearing  peace 
and  comfort.  Steam  has  converted  rivers  into  roads,  which  can  be  trav- 
ersed both  in  a  downward  and  upward  direction,  and  a  floating  popula- 
tion is  constantly  pervading  their  surface.  Far  from  forming  a  barrier  to 
nations,  rivers  are  the  means  of  mobilizing  them  :  they  are  continents  set 
in  motion.  Aided  by  rivers,  the  mountaineers  of  the  Alps  and  Pyrenees 
make  their  way  to  the  Atlantic  and  the  Mediterranean,  while  the  inhab- 
itants of  the  sea-coast  ascend  to  the  elevated  districts  in  the  interior  of 
the  continent. 

In  the  present  day  water-courses  no  longer  assume,  in  the  history  of  civ- 
ilization, the  high  importance  they  once  possessed,  for  now  they  are  not 
the  only  ways  of  communication  between  nations.  No  river  can  now  be 
all  that  the  Nile  was  to  the  Egyptians,  at  once  their  father  and  their  god, 
the  cause  from  which  sprung  both  a  race  of  husbandmen  and  also  the 
harvests  which  they  gathered  on  the  river-mud,  warmed  by  the  rays  of 
the  sun.  Another  Ganges,  with  its  sacred  waves,  will  never  again  flow 
over  the  surface  of  the  earth,  for  man  is  no  longer  the  slave  of  nature. 
He  can  now  develop  artificial  roads,  which  are  shorter  and  more  speedy 
than  the  roads  formed  by  nature ;  and  this  second,  and  even  more  vital 
nature,  which  he  has  created  by  the  labor  of  his  own  hands,  supersedes 
his  adoration  of  that  first  nature  which  he  has  succeeded  in  rcsculatingr. 


.  382 


THE  EARTH. 


Nevertheless,  rivers  will  be  more  important  as  servants  than  they  have 
ever  been  as  gods.  They  bear  upon  their  waters  ships,  and  the  products 
with  which  they  are  freighted,  and  serve  as  arteries  to  vast  organisms  of 
mountains,  valleys,  and  plains,  which  are  sprinkled  over  with  thousands 
of  towns  and  millions  of  inhabitants.  They  vivify  the  earth  by  their  mo- 
tion, carve  it  out  afresh  by  their  erosions,  and  add  to  it  by  their  ever-in- 
craising  deltas.  Some  day,  when  the  hand  of  man  will  be  enabled  to 
guide  rivers  and  to  trace  out  for  them  their  beds,  he  will  employ  these 
potent  workmen  to  carve  out  a  nature  in  harmony  with  his  own  will;  wa- 
ter-courses will  wear  away  the  hills,  fill  up  lakes,  and  throw  out  promon- 
tories into  the  sea  in  obedience  to  his  orders:  their  eternal  and  mighty 
vitality  will  become  the  complement  of  ours. 


FORMATION  OF  LAKEH,  383 


CHAPTER  LVL 

LAKES.  —  FORMATION  OF  LAKES.  —  THEIR  INCREASE  AND  DIMINUTION. — 
THEIR  FORM  AND  THEIR  DEPTH. — LAKES  LYING  IN  SUCCESSIVE*  GRADA- 
TIONS  OP   ELEVATION. 

Collections' of  water — ponds,  pools,  lakes,  or  inland  seas — are  formed 
in  every  depression  of  the  ground  which  receives  a  larger  quantity  of  liq- 
uid, either  from  rivei-s  or  directly  from  the  clouds,  than  it  can  get  rid  of 
through  its  affluents,  or  transfer  to  the  atmosphere  in  the  form  of  vapor. 
Hence  arises  that  infinite  variety  of  lacustrine  sheets  of  water  which  gives 
so  much  grace  or  grandeur  to  landscapes,  and  exercises  such  a  considera- 
ble influence  on  the  action  of  rivers,  on  climates,  on  the  productions  of  the 
soil,  and  consequently  on  the  development  of  mankind. 

The  liquid  mass  contained  in  any  basin  on  the  surface  of  the  earth  does 
not  increase  to  an  indefinite  extent,  even  when  considerable  quantities  of 
water  are  constantly  being  poured  into  it  by  its  tributaries.  Either  the 
basin  completely  fills  up,  and  the  ovei-flow  is  emptied  out  through  the  low- 
est depression  in  its  rim,  or  the  lacustrine  sheet,  gradually  enlarging  in 
area,  ultimately  presents  a  surface  sufficiently  extensive  for  evaporation 
to  establish  an  equipoise  to  the  supply  of  water. 

Perfect  equality  between  the  mass  of  water  received  and  that  which  es- 
capes does  not,  however,  exist  in  any  lake,  and,  consequently,  the  level 
never  ceases  to  fluctuate ;  sometimes  it  rises  and  sometimes  it  sinks,  accord- 
ing to  the  various  seasons  and  years.  After  heavy  falls  of  rain,  or  at  the 
time  of  the  melting  of  the  snow,  some  pools  are  changed  into  perfect  lakes, 
in  the  same  way  as,  during  l«ng  periods  of  drought,  some  lacustrine  basins 
entirely  dry  up.  The  great  phenomena  of  the  vitality  of  the  globe — such 
as  the  upheavals  and  sinkings  of  the  ground,  the  growth  of  mountain-ridg- 
es, the  encroachments  or  retirement  of  the  shores  of  continents,  the  alter- 
nations of  the  winds  and  rains,  land-slips,  and  the  rupture  of  natural  dikes 
— all  have  the  efiect  of  either  giving  rise  to  and  increasing,  or  of  doing 
away  with  or  diminishing,  the  masses  of  water  which  are  collected  in  the 
interior  of  continents.  Like  every  thing  else  which  exists  on  the  surface 
of  the  globe,  lakes  have  their  periods  of  increase  and  decrease,  and  even 
within  the  limited  period  during  which  man  has  begun  to  record  the  an- 
nals of  his  .planet  numbers  of  fresh  lakes  have  made  their  appearance, 
while  many  othere  have  entirely  dried  up,  or  have  considerably  dimin- 
ished in  extent. 

In  mountainous  regions  it  is  a  well-known  fact  that  the  fall  of  rocks  and 
the  advance  of  glaciers  have  often  caused  the  formation  of  considerable 
lakes.    In  like  manner,  some  of  the  large  lakes  of  the  Landes  have  appear- 


384  ^^^  EARTH. 

ed  since  the  Middle  Ages,  owing  to  the  cutting  down  of  the  trees  upon  the 
dunes,  and  the  shifting  of  the  latter  toward  the  east.*  On  the  other  hand, 
instances  of  lakes  which  have  disappeared  owing  to  natural  causes,  with- 
out being  subjected  to  any  human  labor  in  the  process  of  their  exhaustion, 
are  likewise  very  numerous. 

Thus  the  plain  of  Oisans,  in  the  Alps  of  Dauphiny,  having  been  sudden- 
ly closed  up  in  1181  by  a  downfall  of  rocks  which  came  from  the  sides  of 
the  Voiviene,  the  waters  qf  the  Ronianche,  the  Olle,  and  the  V6neon  accu- 
mulated above  the  obstacle,  and  spread  out  into  a  lake  of  6-^  miles  in 
length.  Villages,  vast  plains,  and  whole  forests  were  swallowed  up  under 
a  liquid  sheet  of  an  average  depth  of  33  feet,  and  the  loCal  employment 
gradually  became  that  of  fishing.  The  lake  existed  for  thirty-eight  years, 
and  then  the  barrier  of  debrk  suddenly  yielded  under  the  pressure  of  the 
water,  and  the  body  of  liquid  rushed  like  a  deluge  over  Grenoble,  and  all 
the  towns  and  plains  on  the  banks  of  the  Isere.  At  the  commencement 
of  the  fourteenth  century,  the  former  lake,  which  had  received  the  name 
of  the  Lake  of  St.  Laurent,  was  completely  dried  up. 

The  formation  of  lakes  of  this  kind  above  some  dam  of  rubbish,  and  their 
disappearance  when  these  dams  are  broken  down,  may,  however,  be  con- 
sidered as  accidental  phenomena,  and  not  dependent  directly  upon  climate. 
In  this  latter  respect,  the  changes  in  level  which  are  exhibited  by  some 
great  lacustraL  sheets,  such  as  the  lakes  ofTiticaca  and  Van,  are  much 
more  remarkable  facts.  Travelers  assert  that  the  area  of  the  immense 
Bolivian  lake  has  always  been  diminishing  since  the  commencement  of  the 
historical  period.  Its  water  once  bathed  the  walls  of  Tia-Huanacu,  one  of 
the  principal  cities  of  the  Incas;  but  this  locality  is  now  situated  12^  miles 
from  the  lake,  and  more  than  130  feet  above  the  level  of  its  water.  This 
would  be  a  remarkable  proof  of  the  increase  of  dryness  on  the  high  pla- 
teaux ofBolivia.f  On  the  other  hand,  the  height  of  the  Lake  of  Van  con- 
tinues to  increase — a  fact  which  is  confirmed  by  travelers  every  year. 
The  inhabitants  on  its  shores  are  frequently  obliged  to  turn  the  sea-shore 
roads  farther  inland;  ancient  villages  have  been  swallowed  up,  and  in 
some  spots  the  ruins  buried  by  the  water  are  still  visible.  Finally,  the 
town  of  Erdjisch,  which  was  once  separated  from  the  lake  by  a  great  plain, 
is  nowadays  invaded  by  the  water,  and  the  city  of  Van  itself,  which  was 
once  far  from  the  shore,  is  now  quite  close  to  it.  A  legend,  which  ex- 
plains in  its  own  way  the  constant  swelling  of  the  water,  relates  that  some 
capricious  nomads,  having  obstructed  an  outflow  of  the  lake,  afterward 
made  useless  efforts  to  re-establish  the  former  outlet ;  but,  since  this  date, 
the  irritated  lake  has  never  left  off"  covering  a  fresh  extent  of  plain  every 
year.t 

As  a  simple  process  of  reasoning  must  point  out,  lakes  are  most  numer- 
ous and  most  extensive  in  those  countries  where  rain  falls  in  considerable 
quantities,  and  the  surface  of  which,  although  but  slightly  undulated,  is 

*  Vide  the  chapter  on  "Dunes."  t  Pentland;  BoWaert,  Antiqicities. 

i  Otto  Blau,  Mittheilunrjen  von  Fetermann,  vol,  fii.,  1863. 


FORMATION  OF  LAKES. 


385 


nevertheless  formed  of  compact  rocks  which  do  not  allow  the  water  to  flow 
away  into  the  depths  below,  and  retain  it  as  if  in  natural  basins.  Of  this 
kind  are  the  regions  of  North  America,  in  which  lies  the  fresh-water  Med- 
iterranean crossed  by  the  St.  Lawrence,  the  Winnipeg,  Winnipegoos,  Bear 
and  Slave  Lakes,  and  several  other  sheets  of  water  of  less  extent.  In  these 
districts  there  is  certainly  less  rain  than  in  the  tropical  zone,  and  even  than 
in  most  of  the  countries  of  the  temperate  zone ;  for  the  depth  of  rain  and 
snow  water  does  not  attain  to  more  than  three  feet  in  a  year.  But  the 
granitic  soil  retains  in  the  shallower  depressions  the  moisture  which  falls 
from  the  atmosphere ;  evaporation  does  not  take  place  actively,  and  the 
slopes  toward  the  diflerent  seas  are  not  sufficiently  inclined  for  the  numer- 
ous rivers  to  be  able  to  pour  down  to  the  ocean  all  the  surplus  waters. 

The  island  of  Newfoundland  is  also  in  great  part  granitic,  and  is  like- 
wise covered  by  lakes  maintained  by  the  constant  humidity  which  pre- 
vails in  those  parts  of  the  sea.  In  like  manner,  in  Europe,  the  eastern  val- 
leys of  the  Scandinavian  mountains  and  the  plains  of  Sweden  exhibit  a 
perfect  labyrinth  of  lakes,  some  of  which  are  very  small,  while  others 
stretch  away  and  are  lost  on  the  distant  horizon,  save  where  they  are  dot- 
ted over  with  archipelagoes,  rocks,  and  islets,  like  the  Lake  of  Malar,  which 


Fig.  152.  Lakes  of  Finland. 

contains  no  less  than  1260  islands.     On  the  other  side  of  the  Gulf  of  Both- 
nia, the  granite  plains  of  Finland  are  sprinkled  still  thicker  with  lakes  than 

B  B 


386 


THE  EARTH. 


those  of  Scandinavia  itself,  so  that  the  whole  country  may  be  considered 
as  an  immense  sheet  of  water  intersected  by  innumerable  isthmuses  cross- 
ing one  another  in  every  direction. 

Labyrinths  of  lakes  of  an  altogether  similar  character  are  also  found  in 
countries  where  the  soil,  although  not  rocky,  lies  on  a  clayey  or  ochreous 
subsoil,  which  is  entirely  impervious  to  water.  Thus  there  used  to  exist 
in  the  French  landes  a  great  number  of  pools  which  the  bed  of  alios  re- 
tained on  the  surface  ;*  these  are  at  the  present  time  mostly  dried  up.  In 
the  same  way  Sologne,  Brenne,  and  some  other  solitudes  in  central  France 
were  dotted  over  with  shallow  pieces  of  water.     La  Dombes,  a  plateau  of 


Fig.  163.  The  Dombes. 

about  300  feet  in  height,  which  extends  to  the  northeast  of  Lyons,  between 
the  Rhone,  the  Saone,  the  Veyle,  and  the  Ain,  is  also  covered  with  a  mul- 
titude of  pools,  occupying  altogether  an  area  of  more  than  47,000  acres. 
It  is  a  feet  that  in  this  part  of  France  man  has  unfortunately  lent  his  aid 

*  Vide  above,  p.  83. 


DLMSN8I0NS  OF  LAKES. 


387 


to  the  work  of  nature.  Most  of  the  pools  of  the  Dombes  are  of  artificial 
origin,  and  their  being  laid  dry  would  cost  even  less  than  their  construc- 
tion. They  serve  as  fish-ponds  for  the  wretched  inhabitants  of  the  neigh- 
boring villages,  and  then,  being  emptied  and  cultivated  for  cereals,  they 
are  again  filled  up  and  stocked  with  fish. 

The  form  of  a  lake  always  beai*s  some  relation  to  the  general  relief  of 
the  ground  in  the  depression  of  which  its  water  is  contained ;  its  outline 
and  the  profile  of  its  bed  harmonize  perfectly  with  the  continental  archi- 
tecture. The  water  of  alluvial,  oozy  soil  is  spread  out  in  vast  marshes,  in 
which  it  is  diflScult  to  point  out  the  precise  spot  where  the  dry  ground 
ends  and  the  water  begins.  The  liquid  sheets  of  low  plains,  deserts,  and 
level  plateaux  present  generally  more  sharply-defined  outlines ;  but  their 
depth  is  but  slight  in  comparison  to  their  extent,  and  the  least  fluctuation 
in  level  considerably  modifies  the  line  of  their  banks.  The  lakes  of  more 
undulating  regions  are  in  general  tolerably  deep  in  proportion  to  their  ex- 
tent, and  present  bays  and  promontories  of  a  more  varied  and  picturesque 


,i6a> 


Li3to 


Annge 


IMS 


Genera 


133o 


f  MS 

,  A*    I.0*«l  of  fli»  Sea 


eS3 


Cdmo 


beo 


SSoFe«t 
-990 

tSba 


1S1»' 


Fig.  154.  Altitudes  and  Depths  of  Lakes  In  Italy  and  Savoy. 


character  than  the  sheets  of  water  in  the  plains.  But  the  place  where 
lakes  exhibit  all  their  beauty  is  round  the  bases  oflofty  mountains.  There 
torrents  run  down  into  them,  falling  over  in  rapids  and  cascades ;  green 
glens  slope  down  to  their  very  margin ;  the  spurs  of  the  mountain  plunge 
straight  down  into  their  waters,  and  the  shores  between  the  headlands 
are  traced  out  in  gracefully-curved  bays.  By  the  harmony  and  variety 
of  lines  presented  by  their  outline,  these  lakes  seem  almost  a  necessary 
feature  of  the  landscape,  and  their  horizontal  surface,  by  the  contrast 
which  it  affords,  gives  a  more  noble  appearance  to  the  surrounding  moun- 
tains. 

Lakes,  like  seas,  are  in  general  all  the  deeper  as  the  cliffs  which  over- 
hang them  are  the  more  steeply  escarped ;  indeed  the  cavities  which  are 


388 


THE  EARTH. 


filled  up  by  the  water  seem  to  correspond  in  their  dimensions  to  the  height 
of  the  upheaved  masses.  Thus,  to  bring  forward  no  other  instances  than 
those  of  the  Alpine  lakes,  the  deepest  of  these  lakes  are  found  at  the  south- 
em  base  of  the  Alps,  which  on  this  side  present  their  steepest  slopes. 
Lake  Maggiore,  the  level  of  which  is  652  feet  above  the  Adriatic,  is  no  less 
than  2800  feet  in  depth;  the  Lake  Como  is  1981  feet  deep  in  the  lowest 


Thunn         Bnci» 
ITbrat         Biemte         ^^S^'        P^     luoeme 


...V  Wofflmstodt 


Sea  level 


Fig.  155.  Altitudes  and  Depths  of  Lakes  in  North  Switzerland. 

part  of  its  basin.  The  Lakes  of  Garda  and  Iseo  are  not  so  deep,  but  still 
deep  enough  to  descend  far  below  the  level  of  the  sea.  If  we  could  sup- 
l)ose  the  whole  body  of  the  Alps  cut  down  to  the  level  of  the  sea,  the 
abysses  of  the  water  in  the  Lakes  of  Maggiore,  Como,  Garda,  and  Iseo  would 
still  be  respectively  2149, 1318,  518,  and  426  feet  in  depth  ;  while,  on  the 
other  side  of  the  Alps,  the  only  lake  which  has  a  bed  below  the  level  of 
the  sea-water  is  perhaps  that  of  Brienz,  if  it  be  true,  as  Saussure  asserts, 
that  it  is  1968  feet  in  depth.*  The  two  annexed  plates  represent  the  re- 
spective altitudes  of  the  principal  lakes  of  the  Central  Alps  in  comparison 
with  the  level  of  the  sea.  The  results  depicted  in  these  plates  have,  how- 
ever, unfortunately  only  an  approximate  value ;  for  in  the  Alps,  which 
are,  nevertheless,  visited  and  studied  by  so  many  scientific  men,  accurate 
sounding  operations  have  not  yet  been  made  in  some  of  the  most  impor- 
tant lakes.  In  each  of  these  plates  the  depth  has  been  exaggerated  a  hun- 
dred-fold in  comparison  with  the  breadth.  In  order  that  a  clear  idea  may 
be  formed  of  the  shape  of  the  Alpine  lakes,  it  is  necessary  to  annex  here 
the  actual  outline  of  the  depression  of  Lake  Maggiore,  the  deepest  of  all 
the  lacustral  basins  in  the  Alps,  and  of  the  Lake  of  Neuchatel,  the  prin- 
cipal sheet  of  water  in  the  Jura. 


.  158.  Lake  Maggiore. 

Glancing  at  a  map  of  the  Alps,  it  is  impossible  to  avoid  remarking  at 
first  sight  that  the  lakes  are  distributed  in  a  certain  oider  as  regards 
*  Desor,  Schweitzer  Seen,  in  the  Album  de  Combe-Varin. 


LAKE     GAR  DA 


PL.  XVI 1 1 


Dra»m  by    AVuillrinin    alter      5c!ii  .■.. 

PIAF.PEA  Sc  BROTHERS    >'EW  YORK 


£ng^  by  ErKard 


LAKES  OF  THE  ALPS  AND  JURA.  389 

the  great  groups  of  mountains.  Thus  the  Maritime  Alps,  those  of  Viso, 
Provence,  and  Dauphiny,  and  also  the  Mont-Blanc  group,  have  but  a  very 
small  number  of  lakes,  and  even  these  better  deserve  the  name  of  ponds. 
On  the  east  of  Switzerland  the  various  ranges  of  the  Alps,  which  extend 
as  far  as  Turkey,  are  likewise  almost  devoid  of  lakes,  except  in  Southern 
Bavaria  and  the  districts  of  Salzburg,  where  several  masses  of  water  fill 
up  some  narrow  valleys  which  open  nearly  uniformly  from  south  to  north 
between  parallel  chains  of  mountains.     The  noble  lakes  which  form  the 


Fig.  15T.  Lake  of  Neachiitel. 

glory  of  the  Alps  are  all  situated  round  the  central  group  (of  which  the 
Saint  Gothard  occupies  the  middle),  and  in  the  valleys  and  plains  which, 
under  various  names,  form  the  western  limit  of  the  parallel  ridges  of  the 
Jura. 

These  lakes,  which  evidently  owe  their  origin  to  the  star-like  form  of 
the  chains  which  radiate  round  the  Saint  Gothard,  and  to  the  intersection 
of  the  Alpine  system  by  that  of  the  Jura,  have  in  general  elongated  ba- 
sins, tending  either  from  southwest  to  northwest,  or,  perpendicularly  to 
this  direction,  from  southeast  to  northwest.  The  waters  of  the  valleys  of 
the  Jura — for  instance,  the  Lakes  of  Joux  and  Saint  Point — lie  in  the  for- 
mer direction,  likewise  the  great  bodies  of  water  situated  at  the  base  of 
the  limestone  mountains — the  Lakes  of  Neuchatel,  Bienne,  and  Morat.  The 
Alpine  lakes  of  Brienz,  Sarnen,  and  those  of  Engadine  also  lie  in  this  di- 
rection ;  and  even  the  lakes  on  the  Italian  side,  Maggiore  and  Garde,  are 
nearly  parallel  to  the  lacustral  basins  and  mountainous  ridges  of  the  Jura. 
On  the  other  hand,  the  great  Alpine  lakes  of  Constance,  Zurich,  Semijach, 
Zug,  and  Thun  all  stretch  in  a  contrary  direction  to  those  above  named. 
With  regard  to  the  two  magnificent  inland  seas  of  Switzerland,  the  lakes 
of  Geneva  and  Lucerne,  they  owe  their  admirable  shape  to  a  combination 
of  the  two  types.  The  Leman  is  a  lake  of  the  Jura  in  its  lower  part,  and 
an  Alpine  lake  in  its  upper  part;  toward  the  middle  the  two  sheets  meet 
and  cross  one  another.  Li  the  Lake  of  Lucerne  the  two  basins  cross  one 
another  at  right  angles,  and  thus  give  to  the  whole  body  of  water  the 
shape  of  a  cross. 

It  must  likewise  be  remarked  that  the  largest  lakes  are  found  on  the 
courses  of  the  most  plentiful  rivers,  which  goes  to  prove  that  the  same  ge- 
ological laws  have  presided  in  the  formation  of  the  valleys  and  in  hollow- 
ing out  the  lacustral  basins.  The  Lake  of  Constance,  the  largest  of  all, 
receives  the  Rhine,  the  largest  river  in  Switzerland.  The  Leman  is  cross- 
ed by  the  Rhone;  the  Aar  flows  into  the  two  lakes  of  Brienz  and  Thun; 
the  Renss  enters  the  Lake  of  Lucerne,  the  Linth  that  of  Zurich.  An  ar- 
rangement of  this  kind  can  hardly  be  fortuitous,  but  must  depend  on  the 
general  structure  of  the  great  groups  of  the  Alps. 


390 


THE  EARTH. 


In  those  mountains  which  possess  an  architecture  of  almost  perfect  reg- 
ularity, as,  for  instance,  those  of  the  Jura,  it  is  easy  to  classify  the  various 
lakes  according  to  the  form  of  the  depression  which  is  filled  by  their  wa- 
ters. Thus  the  lacustral  sheets  which  spread  out  in  a  valley  between  two 
parallel  ridges  of  mountains  generally  exhibit  outlines  which  are  scarcely 
at  all  broken  and  disposed  in  a  regular  oval ;  the  slopes  of  the  bed  are 
gently  inclined  toward  the  central  part,  the  average  depth  of  which  is  not, 
however,  very  great.  Here  and  there,  and  especially  at  the  two  ends,  the 
banks  are  marshy,  and  it  is  difficult  to  determine  the  exact  spot  at  which 
the  firm  ground  begins.  Among  these  valley  lakes  we  may  mention  those 
of  Joux,  Saint  Point,  and  Bourget. 


Fig.  15S.  Valley. 

In  a  similar  way,  the  combes  and  duses  which  serve  as  reservoirs  to  the 
lakes  confer  on  the  water  which  they  contain  special  characteristics  very 
different  from  those  of  the  lacustrine  basins  in  valleys.  Thus  the  lakes  in 
duses,  lying  crosswise  to  a  chain  of  limestone  mountains,  are  generally 
narrow,  and  the  escarpments  of  the  high  cliffs  which  command  them  de- 
scend to  a  great  depth  below  the  surface  of  the  water.  With  regard  to 
the  lakes  in  combes,  the  amphitheatre-like  reservoirs  which  contain  them 
give  to  the  surroundings  of  each  basin  a  magnificent  aspect  of  grandeur 
and  majesty.  The  water  in  them  is  deeper  than  that  of  the  valley  lakes, 
but  not  so  deep  as  that  of  the  lakes  in  cluses  /  and  it  is  just  in  the  lower 
portion  of  the  lacustrine  cavity  that  the  section  of  water  presents  the 
greatest  thickness. 

It  is,  however,  but  seldom  that — in  the  Swiss  Alps  and  other  moun- 
tainous countries  with  a  deeply  indented  vertical  outline — we  do  not  find 
lakes  which  present  characteristics  of  all  the  different  types.  In  some 
parts  of  their  basins  they  are  lakes  of  the  valley,  and  in  others  they  are 
lakes  like  those  contained  in  cluses  or  combes.  For  this  reason,  what  a  di- 
versity of  appearance  they  present  in  their  shores,  what  picturesque  beau- 
ty in  the  windings  of  their  bays  and  the  succession  of  their  headlands ! 

Between  mountain  ridges  which  are  not  arranged  in  long  parallel  lines 
like  those  of  the  Jura,  valley  lakes  are  not  mere  oval  sheets  of  water ;  they 
extend  in  long  windings  Tike  the  Lakes  Maggiore,  Como,  and  Lugano ;  or 
in  those  valleys  in  which  basins  and  contractions  alternate  in  succession, 
the  lakes  spread  out  and  become  narrow  alternately.  Numerous  instances 
of  this  may  be  seen  in  the  Scandinavian  mountains.  In  a  general  way, 
however,  these  lakes  are  cut  up  into  several  pieces  of  water  lying  in  gra- 
dation, one  above  the  other,  as  if  on  enormous  steps,  and  are  connected  by 


FORMS  OF  LAKES. 


391 


narrow  defiles,  down  which  the  water  of  a  torrent  pours  in  cascades. 
These  lakes,  lying  on  graduated  levels,  are  found  in  the  high  valleys  of 
almost  every  mountainous  country.     In  Switzerland,  the  three  lakes  of 


hi-.  l(il.  Stages  of  Lakes  iu  the  Valley  ofOo. 


Lungern,  Sarnen,  and  Alpnach,  which  are  travei^sed  by  the  River  Aar, 
may  be  mentioned ;  in  the  Pyrenees,  the  mountain  lakes  of  Oo  and  La  Tet, 


392 


THE  EARTH. 


and  the  lakes  of  the  valleys  of  Couplan,  Aygues-Cluses,  and  Estom  Sou- 
biran,  belong  to  the  same  class  of  lacustrine  basins.  In  the  Carpathians 
they  form  those  charming  little  pools  of  Avater  to  -which  the  name  of 


Fig.  162.  Lakes  of  Mors  Elf 


"  meeraugen^''  (eyes  of  the  sea)  has  been  given ;  lastly,  in  Scandinavia, 
lakes  situated  on  graduated  levels  may  be  reckoned  by  hundreds. 


FORMATION  OF  LAKES. 


393 


Laca 
dTstom  Soabip&d 


slalotn*^ 


Fig.  163.  Lake-stages  ofKstom  Soubiran  aud  Estom. 

There,  all  the  rivers,  almost  without  exception,  are,  from  their  source 
to  their  mouth,  nothing  but  chains  of  lakes  connected  with  one  another 
by  rapids  and  cascades.  They  are,  in  fact,  water-courses  in  process  of 
formation,  which  have  not  as  yet  hollowed  out  for  themselves  regular 
beds,  but  flow  in  all  the  natural  depressions  of  the  soil  through  narrow 
channels  which  have  been  opened  since  the  ground  itself  has  risen  above 
the  level  of  the  sea.  The  land  of  Scandinavia  having  risen  only  at  a  re- 
cent epoch  by  a  gradual  movement  of  emergence,  which  at  the  present 
time  is  still  continuing,  the  rivers  have  not  yet  had  time  either  to  fill  up 
with  debris  the  lakes  that  they  meet  with  in  their  course,  or  to  pierce 
wide  valleys  through  the  rocks.* 

*  Vide  the  chapter  on  "  Upheavals  and  Depressions," 


394  ^'JKB  EARTH. 


CHAPTER  LVII. 

VARIOUS  PHENOMENA   IN  LAKES. — COLOR    OF  THEIR   WATERS. — SEICHES. — 
CURRENTS   AND  TIDES. — FORMATION   OP   ICE    IN  LAKES. 

Lakes  are  not  only  distinguished  from  each  other  by  their  shape  and 
the  depth  of  their  basin,  they  also  vary  in  the  appearance  of  their  water, 
and  even  in  this  respect  the  diversity  of  the  matters  held  in  suspension  or 
solution  in  the  liquid  mass  is  not  always  sufficient  to  explain  the  remark- 
able contrast  presented  by  adjacent  sheets  of  water.  The  color  and  trans- 
parency of  the  liquid  differ  astonishingly  in  most  mountain  lakes.  Some 
are  of  an  emerald  green,  others  of  a  sapphire  blue,  a  few  even  have  a 
milky  shade.  There  are  some,  indeed,  the  water  of  which  is  transparent, 
that  have  a  brown  or  yellowish  color.  In  every  ease,  whatever  may  be 
the  natural  hue  of  each  of  these  lakes,  they  incessantly  vary  on  account 
of  the  reflection  of  the  rays  of  the  sun,  the  clouds,  or  the  color  of  the  sky 
and  the  refraction  of  the  light.  One  lake,  the  water  of  which,  not  far  from 
the  bank,  is  of  a  yellowish-green,  owing  to  the  rocky  bottom  just  visible 
below  the  undulations  of  the  surface,  is  of  a  deep  blue  above  the  invisible 
abysses  of  its  central  portion.  Another  lake  presents  a  well-defined  dif- 
ference of  color  between  the  tranquil  water  of  its  basin  and  that  which  is 
brought  in  by  the  rapid  current  of  the  river  which  crosses  it.  In  other 
places,  again,  the  eddies  light  up  the  surface  with  reflections  of  a  bronzed 
or  greenish  hue ;  even  the  particles  of  sand  or  ooze,  as  well  as  the  chem- 
ical substances  dissolved  in  the  water,  must  necessarily,  however  infinites- 
imal their  tenuity  may  be,  tinge  the  liquid  sheet  with  various  shades. 
Vegetable  mould  gives  to  lakes  a  color  more  or  less  shaded  with  red  or 
brown ;  clay  gives  them  a  yellowish  tinge.  As  to  the  debris  of  rocks  and 
pebbles,  these,  according  to  Tyndall,  are  the  agents  which  confer  on  the 
Lake  of  Geneva  and  other  mountain  lakes  their  lovely  azure  color.  The 
most  wonderfully  transparent  water,  which,  too,  is  the  most  devoid  of  all 
impurity,  is  in  general  a  sea-green  hue.  It  is  said  that  objects  are  some- 
times visible  in  it  at  a  depth  of  80  and  even  100  feet. 

All  long  and  narrow  lakes,  over  which  atmospheric  variations  often  take 
effect  in  a  sudden  and  violent  manner,  frequently  exhibit  abrupt  oscilla- 
tions of  level,  which  can  only  be  explained  by  a  difference  in  the  pressure 
of  the  air.  Such  are  t\\e  seiches  of  the  Lake  of  Geneva  and  the  liuhssen 
of  the  Lake  of  Constance,  which  are  noticed  sometimes  at  one  point,  some- 
times at  another.  In  these  purely  local  swellings  of  the  water,  the  latter 
may  rise  all  at  once  some  inches  or  even  a  yard  above  the  level  of  the  sur- 
7'ounding  surface.  The  outbreak  of  subterranean  tributaries  can  not  be 
taken  as  an  explanation  of  the  cause  of  this  sudden  rise,  for  it  takes  place 


SEICHES  AND  LA!KES.  395 

It  the  foot  of  mountains  of  a  compact  formation,  which  certainly  do  not 
conceal  any  considerable  streams  in  the  depths  of  their  rocks.  Added  to 
this,  on  the  surface  of  many  lakes  and  inland  seas  the  phenomena  of  seiches 
have  been  observed  around  islets  and  mere  rocks. 

Schulten  has  proved  that  the  seiches  of  the  Baltic,  which  are  in  every 
respect  similar  to  those  of  the  Lake  of  Geneva,  are  in  direct  connection 
with  the  height  of  the  barometrical  column.  When  the  pressure  of  the 
air  diminishes  the  water  begins  to  swell,  and  when  the  barometer  again 
rises  up  the  surface  of  the  sea  sinks,  only  the  movements  of  the  water  are 
always  a  few  minutes  earlier  than  those  of  the  instrument,  on  account  of 
the  greater  mobility  of  the  aqueous  particles.  Now,  as  the  total  varia- 
tion between  the  difterent  heights  of  the  barometrical  column  at  the  level 
of  the  sea  corresponds  to  a  variation  of  about  a  yard  in  a  column  of  water, 
it  follows  that  the  most  considerable  seiches  can  not  exceed  this  height. 
This  has,  in  fact,  been  verified  by  observations  in  the  Baltic  as  well  as  in 
,  the  Lake  of  Geneva,  and  in  the  great  lakes  of  North  America.  In  the 
midst  of  the  open  sea  seiches  would  likewise  be  produced,  especially  during 
hurricanes ;  but  the  liquid  mass  being  at  full  liberty,  and  able  to  spread 
out  freely  all  round  the  rising  of  the  wave,  the  phenomena  is  there  more 
difficult  to  notice  than  in  narrower  lakes.*  It  is  probable  that  the  phe- 
nomenon known  by  the  Sicilians  by  the  name  of  marubia  (from  mare  ebri- 
uco, "  drunken  sea")  is  also  a  swelling  of  the  water  accompanied  by  the 
barometrical  depression.  It  is  obsei'ved  on  all  the  coasts  of  Sicily,  but 
especially  off  Mazzara,  at  the  precise  spot  where  the  Mediterranean,  con- 
tracting into  the  form  of  a  strait,  is  severed  into  two  basins  by  a  subma- 
rine ledge  which  approaches  the  surface.  Daubeny  considei-s  that  these 
movements  of  water  are  a  sign  of  some  volcanic  vibration  of  the  soil;  yet 
the  description  which  he  himself  gives  of  the  movements  seems  to  indi- 
cate that  they  are  seiches  similar  to  those  in  the  Lake  of  Geneva  and  the 
Baltic.  When  the  mantbia  occurs  the  air  is  calm  and  the  horizon  misty ; 
suddenly  the  water,  stirred  up  in  short  waves,  raises  its  level  about  23 
inches,  and  then,  after  an  interval  of  from  half  an  hour  to  two  hours,  the 
south  wind  begins  to  blow,  and  a  heavy  storm  rises. 

Lakes,  moreover,  which  are,  indeed,  inland  seas  of  fresh  or  salt  water, 
must  exhibit  phenomena  similar  to  those  of  the  ocean.  Lacustrine  sheets 
of  water  have  also  their  tempests,  their  swells,  their  breakers,  ahd  their 
bores ;  and  certain  bays  of  Lakes  Superior,  Ladoga,  and  Baikal  arc  not 
less  dangerous  than  the  Black  Sea  and  the  Bay  of  Biscay.  The  waves 
raised  by  the  wind  in  the  more  confined  areas  of  lakes  are  neither  so  high 
nor  so  rapid  as  those  of  the  sea,  because  they  have  not  so  vast  a  field  on 
which  they  can  spread  out,  and  because  they  do  not  move  over  a  suffi- 
ciently great  depth  of  water.  They  are  short,  compact,  and  "  chopping," 
and  from  this  very  fact  they  are  more  formidable  to  any  ship  against 
which  they  incessantly  dash.  Added  to  this,  the  water  of  most  lakes  being 
fresh,  and  in  consequence  lighter  than  that  of  the  ocean,  it  is  also  more 
*  Anton  von  Etzel,  Die  Ostsee. 


396  *  ^^^  EARTH. 

readily  stirred  up,  and  the  wind  has  scarcely  commenced  to  blow  before 
the  surface  of  the  lake  is  roughened  with  foaming  billows. 

AYith  regard  to  the  currents,  it  is  evident  that  in  lakes  they  can  not  be 
developed  with  the  same  regularity  as  in  great  seas  which  lie  open  and 
exposed  from  the  poles  to  the  equator ;  but  currents  are  nevertheless  pro- 
duced in  every  spot  where  any  perceptible  difterence  in  temperature  exists 
between  two  adjacent  regions  on  the  surface  of  the  sea.  There  is,  of  ne- 
cessity, a  flow  of  cold  water  toward  the  sides  of  the  lake  whenever  the 
superficial  liquid  layers,  heated  by  one  cause  or  another,  are  comparatively 
lighter,  and  sufier  a  greater  loss  from  evaporation.  Besides  these  lateral 
currents,  which  are  sometimes  difticult  to  be  certain  about,  there  are  also, 
in  lakes  as  in  the  sea,  interchanging  currents  flowing  between  the  upper 
sheet  of  water  and  the  masses  underneath.  Moreover,  all  the  rivers  which 
cross  an  open  lake  or  fall  into  a  closed-up  lake,  like  the  Rhone,  the  Rhine, 
the  Reuss,  and  the  Jordan,  determine  the  formation  of  local  currents,  from 
each  side  of  which  the  water  of  the  basin  flows  back  in  a  contrary  direc- 
tion. Lastly,  lacustrine  basins  also  have  their  tides,  although  these  phe- 
nomena are  generally  nearly  imperceptible,  and  are  only  discovered  by  a 
long  and  attentive  series  of  observations  of  the  oscillations  of  the  level. 
In  Lake  Michigan  the  height  of  the  tide  reaches  to  about  3  inches. 

One  of  the  most  curious  phenomena  in  the  lakes  of  the  northern  tem- 
perate and  polar  zones  is  that  of  the  formation  of  ice.  In  winter,  when 
the  sheet  of  water  is  perfectly  still,  needles  of  ice,  radiating  one  from  the 
other  at  angles  of  from  60  to  120  degrees,  appear  on  the  surface;  then, 
joining  their  net-work  together,  they  soon  form  a  level  sheet  of  ice.  On 
the  contrary,  when  the  water  is  violently  agitated  by  a  storm,  the  first 
needles  of  ice,  being  incessantly  bruised  and  rubbed  against  each  other, 
agglomerate  in  disks  rounded  by  the  friction,  and  the  whole  of  the  con- 
gealed mass  ultimately  presents  an  uneven  surface  like  that  of  rivers  with 
a  rapid  and  violent  current.  The  ice  of  lakes  i&  generally  much  more  reg- 
ular and  transparent  than  that  of  water-courses,  in  which  the  process  of 
crystallization  is  nearly  always  being  disturbed.  When  a  prism  of  this 
pure  ice  is  exposed  to  the  influence  of  a  ray  of  the  sun  concentrated  upon 
it  by  a  lens,  a  multitude  of  little  corollas,  with  six  sepals  arranged  round 
a  glittering  point,  suddenly  appear  in  the  thickness  of  the  prism.  This  is 
one  of  the  most  charming  sights  which  the  beauties  of  nature  can  j^resent 
to  the  eyes  of  an  observer.* 

When  the  whole  extent  of  the  covering  of  ice  is  solidified  over  the 
water,  it  does  not  remain  immovable  until  the  thaw ;  on  the  contrary,  it  is 
constantly  agitated  by  various  movements,  according  to  the  state  of  the 
atmosphere  and  the  phenomena  which  are  going  on  in  the  liquid  mass  be- 
neath. If  the  temperature  diminish,  the  lower  side  of  the  frozen  crust  is 
immediately  increased  by  a  fresh  layer  of  ice  more  expanded  than  the 
water;  the  sheet  must  therefore  necessarily  rise  and  form  a  somewhat 
curved  surface.  If  the  cold  become  less  intense,  the  solid  mass  conse- 
*  Tyndall,  Glaciers  of  the  Alps. 


THE  ICE  OF  LAKES.  397 

quently  grows  thinner,  and  forms  hollows  in  some  places.  "When  the  level 
of  the  lake  rises,  owing  to  any  larger  quantity  of  water  being  poured  into 
it  by  its  affluents,  the  arch  of  ice  is  upheaved  unequally  by  the  liquid, 
sheets  which  How  beneath  it.  If  the  supply  of  water  diminish,  and  tlie 
level  of  the  lake  consequently  sinks,  the  solid  cover  simultaneously  gives 
way,  owing  to  its  own  weight,  and  splits  up  so  as  to  follow  the  downward 
movement  of  the  water.  Lastly,  the  long  undulations  which  are  produced 
in  the  liquid  mass  by  shocks  received  on  the  surface,  the  large  quantity 
of  air  which  makes  its  way  under  the  sheet  of  ice  either  in  considerable 
bodies  or  isolated  bubbles,  even  the  gas  incessantly  being  evolved  by  the 
respiration  of  the  fish,  all  combine  in  producing  the  same  result — that  is, 
the  upheaval  of  .the  ice.  The  comparatively  thin  crust  which  separates 
the  hidden  water  from  the  great  atmospheric  ocean  is  constantly  being 
drawn  sometimes  in  one  direction,  sometimes  in  another.  Enormous  crev- 
ices, generally  tending  in  the  direction  of  the  greatest  length  of  the  lake, 
open  suddenly  with  a  terrible  crash ;  the  roaring  of  the  air  wliich  penetrates 
under  the  icy  layer,  or  which  escapes  from  it,  is  mingled  with  the  cjack- 
ling  of  the  breaking  crystals ;  we  have  simultaneously  noises  like  the  roll- 
ing of  thunder  and  the  rattling  of  musketry.  On  that  part  of  the  Lake 
of  Constance  which  is  called  the  Untersee,  M.  Deiche  has  noticed  cracks 
in  the  ice  which  were  six  miles  long  and  13  to  16  feet  wide. 

In  the  great  lakes  of  North  America,  and  also  in  those  of  Siberia,  espe- 
cially in  Lake  Baikal,  the  phenomenon  of  the  formation  of  ice  takes  place 
in  the  most  magnificent  way.  During  thi*ee  months  of  winter,  the  mighty 
Baikal,  the  inland  sea  in  which  seals  live  and  coral-stems  grow  as  in  tlie 
ocean,  is  covered  by  a  field  of  ice,  presenting  in  some  places  a  thickness  of 
6  to  9  feet.  The  vast  sheet  of  water,  extending  over  an  area  of  more  than 
1400  square  miles,  and  surrounded  by  mountains  as  high  as  the  Alps,  and 
glittering  with  glaciers,  is  nothing  but  a  solid  mass,  on  which  caravans  of 
travelers  venture  without  fear.  Sometimes,  when  the  ice  begins  to  form, 
a  sudden  tempest  reduces  it  to  fragments,  which,  under  the  pressure  of 
fresh  pieces  of  ice,  brought  by  the  waves  and  currents,  are  piled  up  one 
on  the  other,  intermingling  in  a  kind  of  chaos  which  calls  to  mind  the 
aeracs  of  the  Alpine  glaciers.  Subsequently,  when  the  water  is  entirely 
covered  with  its  heavy  shell,  the  latter  is  occasionally  rent  asunder,  and 
shrill  whistlings,  dull  cracking  noises,  prolonged  thunder-like  rumblings, 
mingled  with  innumerable  partial  crepitations,  are  heard  while  the  ice  is 
bending  and  breaking.  The  water  springs  out  from  the  fissure  in  vertical 
sheets,  and,  falling  down  again  on  the  surface,  forms  risings  on  each  side 
of  the  crack  which  is  sometimes  more  than  a  yard  wide.  Sometimes  a 
fragment  of  the  broken  layer  of  ice  sinks  below  the  general  level;  anoth- 
er piece,  being  pressed  on  in  every  direction  by  the  frozen  masses,  curves 
perceptibly  in  the  middle.  All  these  movements  of  the  solid  crust  pro- 
duce long  undulations  in  the  water  beneath.  Travelers,  borne  along  rap- 
idly in  their  sledges  over  the  ice  of  the  lake,  feel  distinctly  the  shock  of 
the  waves  breaking  against  the  lower  side  of  the  trembling  floor  beneath 


398  "^^^  EARTH. 

them.  On  the  sides  of  the  cliffs  which  border  on  the  lake  may  be  noticed 
heaps  of  solidified  flakes,  sometimes  resembling  a  cascade ;  this  is  the  foam 
which  is  jetted  out  at  the  time  of  the  violent  rupture  of  the  ice,  and  has 
hardened  upon  the  rocks  before  it  had  time  to  fall.*  In  a  general  way. 
Lake  Baikal  freezes  so  rapidly  that,  according  to  the  statement  of  the  na- 
tives, the  ice  begins  by  adhering  to  the  bottom  of  the  lake,  from  which  it 
afterward  becomes  detached  with  a  terrible  noise,  and  rises  to  the  surface.f 
But  this  fact,  which  could  not  take  place  unless  the  temperature  of  the 
deep  water  was  much  lower  than  that  of  the  surface  which  is  traversed  by 
freezing  winds,  has  not  yet  been  scientifically  verified.  It  is,  on  the  con- 
trary, very  probable  that  the  water  on  the  bottom  remains  constantly  liq- 
uid. At  the  temperature  of  39°  Fahr.  the  aqueous  particles  acquire  their 
greatest  density,  and  consequently  their  heaviest  specific  gravity.  In  obe- 
dience to  the  law  of  gravity,  the  layers  which  are  at  39°  Fahr.  of  temper- 
ature are  those  which  must  lie  upon  the  bottom  of  the  lake,  and  therefore 
ice  can  only  be  formed  on  the  surface.  The  direct  observations  which 
have  been  made  as  to  the  temperature  of  the  Swiss  lakes  confirm  this  the- 
ory. In  the  Lake  of  Geneva,  the  effects  of  meteorological  variations  are 
not  felt  below  a  depth  of  236  feet,  and  deeper  still  the  constant  temper- 
ature is  42°  Fahr.  In  the  Lake  of  Constance  the  temperature  is  lower ; 
there  it  is  only  39°  Fahr,,  and  in  the  Lake  of  Lausanne  39°  12'  Fahr. ;  this 
comparatively  slight  excess  of  heat  is  probably  owing  to  the  natural 
wai'mth  of  the  ground.  J  Added  to  this,  in  the  environs  of  Boston,  where 
all  the  small  lakes  are  regularly  worked  during  winter,  and  furnish  for  the 
demands  of  commerce  more  than  200,000  tons  of  ice  a  year,  the  solid  layer 
of  ice  has  never  been  noticed  to  form  in  the  first  place  at  the  bottom  of 
the  basin. 

*  Russell-Killough,  Seize  Mille  Liettes.  t  Carl  Bitter,  Erdkunde. 

%  Buff,  Physik  der  Erde. 


BEQ  ULA  TING  A  CTION  OF  LAKES.  399 


CHAPTER  LYIil. 

LAKES     ACTING    AS    REGULATORS    OF    THE     RIVERS    WHICH    PASS    THROUGH 
THEM. — FRESH-WATER  AND  SALT-WATER  LAKES. — ^THB   CASPIAN  SEA, 

Those  lakes  which  receive  a  superabundant  quantity  of  water — and 
these  constitute  the  most  numerous  class — give  rise  to  a  river  which  car- 
ries off  the  surplus  of  the  liquid  mass  poui'ed  into  the  basin  by  the  upper 
affluents.  These  lacustrine  reservoirs  may  then  be  considered  as  expan- 
sions, to  some  extent,  of  the  fluviatile  valley ;  in  this  point  of  view,  the 
Lake  of  Geneva  would  be  the  Rhone,  and  become  a  hundred  times  wider 
and  deeper.  The  Lake  of  Constance  would  be  an  immense  hollow  of  the 
Rhine,  containing  in  its  reservoir  nearly  a  hundred  times  as  much  water 
as  all  the  rest  of  the  river.  In  like  manner,  the  great  inland  lakes  of  North 
America — Superior,  Michigan,  Huron,  Erie,  and  Ontario — form  the  first 
part  of  the  course  of  the  St.  Lawrence,  a  river  of  such  slight  importance 
in  comparison  to  the  vast  basins  which  feed  it. 

The  large  basins  in  which  the  water  of  a  river  is  spread  out  before  it 
again  takes  its  course  down  to  the'  ocean,  regulate  the  discharge  of  their 
out-flows  all  the  more  efficiently  the  more  extensive  the  area  over  which 
they  extend.  Very  considerable  inundations  in  a  stream  produce  com- 
paratively but  a  slight  rise  in  the  level  of  a  lake,  because  the  water  has  to 
be  diffused  over  the  whole  surface  of  the  basin,  and  loses  in  depth  all  that 
it  gains  in  breadth.  During  the  season  when  the  ice  is  melting — that  is, 
in  spring  and  summer — the  Lake  of  Geneva  rises  on  the  average  six  feet 
above  the  low-water  of  winter,  and  consequently  contains  a  surplus  mass 
of  1,572,000,000  cubic  yards  of  water.  The  gauges  used  at  Geneva  estab- 
lish the  fact  that  the  discharge  of  the  Rhone  at  its  issue  from  the  lake  is 
at  its  maximum  753  cubic  yards ;  now,  as  the  various  affluents  of  the  lake 
supply  more  than  1400  cubic  yards  during  their  highest  floods,  it  is  evi- 
dent that  the  Lake  of  Geneva  acts  as  a  complete  regulator.  It  keeps 
back  at  least  one  half  of  the  inundation-water,  which  it  subsequently  emp- 
ties down  gradually  when  its  tributaries  have  retired  to  their  usual  level. 
It  is  certain  that,  owing  to  the  regulating  actiflfn  exercised  over  the  dis- 
charge of  the  river,  the  plains  on  the  banks  of  the  middle  course  of  the 
Rhone,  from  Geneva  to  Lyons,  are  comparatively  protected  against  floods. 
The  equilibrium  in  the  action  of  the  river  would  be  still  more  complete  if 
a  dam  were  constructed  at  Geneva,  with  flood-gates  to  regulate  at  will 
the  discharge  of  the  water.* 

Lakes  which  are  crossed  by  rivers  must  be,  almost  without  exception, 
fresh-water  basins,  as  the  saline  particles  which  are  carried  into  the  basin 
*  L.  L.  and  E.  Vallee,  Du  Barrage  de  Geneve. 


400  T^^  EABTH. 

by  one  or  more  affluents  are  conveyed  out  of  it  with  the  surphis  water. 
Still,  lakes  of  no  great  area,  which  are  mostly  fed  by  salt  springs,  discharge 
brackish  water  through  their  out-flows.  As  regards  lakes  without  any 
outlet,  it  is  evident  that  the  saline  particles  brought  into  them  by  tribu- 
taries can  not  make  their  escape,  and  must  consequently  be  deposited  on 
the  edges,  or  must  more  and  more  saturate  the  liquid  mass.  Except  they 
are  fed  by  affluents  entirely  devoid  of  saline  matter,  lakes  which  are  with- 
out any  communication  with  the  sea  must  therefore  more  or  less  resem- 
ble the  ocean  in  the  composition  of  their  waters.  Almost  all  the  lakes 
without  outlet  are  filled  with  water  more  or  less  saline.  It  must,  how- 
ever, be  understood  that  the  proportion  of  salt  varies  in  all  inland  basins, 
and  the  transition  is  most  gradual  between  the  condition  of  water  called 
fresh,  and  that  of  brackish  or  salt  water. 

The  largest  inland  sea  devoid  of  any  outlet — the  Caspian — is  the  re- 
mains of  that  great  central  sea  which  once  extended  from  the  Euxine  to 
the  Frozen  Ocean.  It  is  probable  that  the  slow  upheaval  of  Siberia  and 
Tai'tary  has  gradually  separated  the  Caspian  from  the  Gulf  of  Obi  and  the 
Sea  of  Aral,  and  that  subsequently  the  rupture  of  the  Bosphorus,  by  low- 
ering the  level  of  the  water  of  the  Black  Sea,  has  laid  dry  the  Ponto-Cas- 
pian  isthmus,  which  is  now  traversed  by  the  waters  of  the  Manytch.  Be 
that  as  it  may,  it  is  certain  that  by  remaining  isolated  in  the  middle  of 
the  land,  the  Caspian  has  lost  by  evaporation  a  larger  quantity  of  water 
than  is  supplied  to  it  by  its  tributary  "rivers;  for  it  has  gradually  dimin- 
ished in  extent,  and  its  level  has  sunk  more  than  80  feet  below  that  of  the 
Black  Sea.  If  the  Caspian  was  again  to  fill  up  the  whole  concavity  of  its 
basin  to  a  height  corresponding  to  that  of  the  adjacent  open  seas,  it  wonld 
inundate  the  whole  plain  of  the  Volga  below  Saratov,  and  would  cover  the 
surface  of  the  steppes  for  an  area  of  several  hundred  thousand  square  miles. 

The  Caspian  Sea  is  divided  into  thi*ee  distinct  parts.  The  northern  por- 
tion— the  bottom  of  which  continues  the  almost  imperceptible  slope  of  the 
steppe — is  a  vast  marsh,  which  is  nowhere  more  than  48  to  50  feet  deep, 
which,  too,  several  rivers  are  constantly  engaged  in  filling  up  with  their 
alluvium.  In  the  southern  part  of  this  sea  of  steppes  lies  the  central  ba- 
sin of  the  Caspian,  which  is  bounded  on  the  south  by  the  promontory  of 
Apcheron,  a  prolongation  of  the  Caucasus.  The  southern  basin,  mostly 
surrounded  by  high  mountains,  the  escarpments  of  which  extend  beneath 
the  water,  is  also  the  deepest.  In  some  spots  soundings  have  been  made 
ofl7V2  and  2953  feet.       • 

The  saltness  of  the  water  is  very  unequal  in  different  parts  of  the  Cas- 
pian. On  the  north,  the  Terek,  the  Oural,  and  especially  the  Volga,  bring 
down  to  the  sea  an  enormous  liquid  mass,  so  much  so  that  the  total  salt- 
ness is  only  from  15  to  16  ten  thousandths,  and  at  many  of  the  post  sta- 
tions, where  there  is  a  deficiency  of  springs,  they  drink  the  sea-water  with- 
out either  dislike  or  danger.  The  central  and  southern  basins,  on  the  con- 
trary, contain  water  which  is  completely  salt.  It  is  proved  by  the  exper- 
iments of  M.  de  Baer  that  the  average  saltness  is  about  nine  thousandths : 


CASPIAN  SEA. 


401 


this  is  a  degree  of  saltness  about  one  third  of  that  of  the  waters  of  the  At- 
lantic Ocean. 


Fig.  164.  Caspian  Sea. 


Is  the  saturation  of  the  Caspian  diminishing  during  the  course  of  ages, 
or  is  it,  on  the  contrary,  in  process  of  increase  ?  At  first  sight  one  is 
•  Co 


402  ^^-^  EABTH. 

tempted  to  admit  the  fact  of  the  increase  of  the  saltness  as  an  evident 
matter,  since  the  soil  of  the  surrounding  steppes  is  gradually  yielding  up 
to  the  sea  the  salt  which  it  contains.  The  rain  and  snow  water,  when 
penetrating  through  the  surface  layer  of  sand,  carry  with  them  the  saline 
particles,  and  concentrate  them  in  the  clayey  subsoil.  In  every  place 
where  the  ground  is  hollowed  out  by  the  ravines,  so  numerous  on  the 
steppes,  the  saline  clay  is  washed  away  by  the  water,  and  carries  the  mat- 
ter with  which  it  is  charged  into  the  Caspian  Sea,  either  directly  or  through 
the  bed  of  a  river.  It  appears,  then,  that  the  waters  of  the  Caspian  ought 
to  present  an  increasingly  large  proportion  of  salt. 

Yet  M.  de  Baer,  who  has  devoted  more  study  to  this  inland  sea  than  any 
other  savant,  does  not  believe  in  any  increase  in  the  degree  of  saltness  in 
the  waters  of  the  Caspian;  and,  in  his  idea,  if  the  proportion  of  salt  be  un- 
dergoing any  change  at  all,  it  is  diminution.  In  fact,  in  the  plains  aban- 
doned by  the  sea,  banks  of  shells  are  here  and  there  to  be  met  with  which 
are  identically  similar  to  those  of  the  shell-fish  which  now  inhabit  the  Cas- 
pian. The  dimensions  of  these  shells,  being  always  proportional  to  the 
quantity  of  salt  contained  in  the  water,  ought  to  indicate  the  degree  of 
saltness  of  the  former  sea,  and  thus  give  a  point  of  comparison.  Now  the 
shells  which  are  picked  up  in  the  vicinity  of  the  Lake  of  Elton,  more  than 
200  miles  from  the  present  sea-shore,  are  as  large  as  those  of  the  molluscs 
which  now  inhabit  the  open  Caspian  at  a  point  60  miles  from  the  mouth 
of  tbe  Volga.  Near  Astrakhan,  where  the  sea-water,  being  mingled  with 
that  of  the  river,  must  be  comparatively  fresh,  the  shells  left  by  the  retire- 
ment of  the  sea  indicate  a  degree  of  saltness  equivalent  to  that  of  the  wa- 
ter in  the  central  basin.  Moreover,  in  the  environs  of  Baku,  on  the  sides 
of  the  hills  which  overlook  the  water,  amid  the  rocks,  shells  of  molluscs 
are  found  which  are  much  larger  than  those  of  the  same  species  now  swim- 
ming in  the  sea  some  yards  lower  down.  This  fact  alone  is  sufficient  to 
afford  considerable  probability  to  M.  de  Baer's  hypothesis  as  to  the  de- 
crease of  saltness  in  the  waters  of  the  Caspian.  The  Black  Sea,  however, 
with  which  the  great  inland  sea  of  Russia  formerly  communicated,  con- 
tains prop'ortionately  twice  the  amount  of  salt. 

How  can  this  decrease  be  possible  ?  How  is  it  that  the  salt  brought 
down  by  the  rivers  and  rivulets  is  able  to  escape  from  the  vast  basin  which 
has  received  it,  and  to  separate  itself  from  the  sea-water  with  which  it  is 
mingled?  Nothing  can  be  more  simple;  by  the  regular  movements  of  its 
waves,  the  Caspian — the  same  as  all  other  seas — throws  up  banks  of  sand 
in  front  of  the  shallow  bays  of  its  shores,  and  thus  converts  gulfs  and 
creeks  into  lagoons,  into  which  the  sea-water  runs  only  through  a  narrow 
channel.  Evaporation,  which  is  very  active  in  these  regions  bordering  on 
the  burning  desert,  is  constantly  tending  to  sink  the  level  of  these  basins, 
while  the  sea-water,  charged  with  salt,  flows  in  without  intermission  to 
maintain  the  equilibrium ;  in  this  way  are  formed  perfect  magazines  of 
salt,  which  are  incessantly  being  increased.  When,  after  heavy  storms  or 
a  lono-  continuation  of  dry  weather,  the  channel  which  communicates  be- 


CASPIAN  SEA.  403 

tween  the  sea  and  the  lagoon  ultimately  becomes  dried  up,  the  sheet  of 
water,  now  completely  isolated,  diminishes  rapidly  in  area,  or  is  even  com- 
pletely absorbed  by  the  atmosphere,  nothing  being  left  of  it  but  a  layer  of 
salt  of  variable  thickness,  which  is  formed  at  the  expense  of  the  sea.  Thus 
it  is  that  the  lagoons  recover  from  'the  Caspian  the  salt  which  the  rivers 
of  the  steppes  carry  down  to  it.  The  only  question  is  to  know  if  equality 
exists  between  the  incomings  and  the  outgoings,  or  if,  in  conformity  to 
M.  de  Baer's  theory,  the  loss  6f  salt  is  more  considerable  than  the  gain. 
A  long  series  of  accurate  observations  could  alone  solve  this  problem. 

The  formation  of  these  salinofi'eservoirs  may  be  studied  all  round  the 
circumference  of  the  Caspian  Sea.  A  former  bay,  situated  not  far  from 
Novo-Petrosk,  on  the  eastera  coast,  is  nowadays  divided  into  a  large  num- 
ber of  basins,  which  present  every  degree  of  saline  concentration.  One 
basin  still  occasionally  receives  water  from  the  sea,  and  has  deposited  on 
its  banks  only  a  very  thin  layer  of  salt.  A  second,  likewise  full  of  water, 
has  its  bottom  hidden  by  a  thick  crust  of  rose-colored  crystals  like  a  pave- 
ment of  marble.  A  third  exhibits  a  compact  mass  of  salt,  in  which  glitter 
here  and  there  pools  of  water,  situated  more  than  a  yard  below  the  level 
of  the  sea.  Lastly,  another  has  lost  by  means  of  evaporation  all  the  water 
which  once  filled  it,  and  the  strata  of  salt  which  cai-pet  its  bed  are  partly 
covered  by  sand.  The  same  facts  are  found  existing  farther  to  the  south, 
in  the  environs  of  the  Bay  of  Alexander,  and  also  quite  at  the  extremity 
of  the  northern  basin,  at  the  point  where  the  arm  of  the  sea  lies,  which  is 
known  under  the  name  of  Karasu  (black  water).  The  saltness  of  the  Ka- 
rasu  exceeds  that  of  the  Gulf  of  Suez,  the  saltest  of  all  the  seas  which  com- 
municate with  the  ocean ;  in  this  part  of  the  Caspian  the  proportion  of 
marine  salt  rises  to  nearly  4  hundredths,  and  all  the  salts  combined  form 
57  thou^ndths  of  the  water;  animal  life,  therefore,  must  there  be  almost, 
if  not  entirely  suppressed. 

Among  the  thousands  of  bays  and  lagoons  in  which  the  salts  of  the 
Caspian  are  stored  up,  none  is  more  remarkable  than  the  Karaboghaz,  a 
kind  of  inland  sea  which  probably  connected  the  Hyrcanian  Sea  with  the 
Lake  of  Aral,  and  into  which  perhaps  the  Oxus  emptied  itself  when  this 
river  was  still  a  tributary  of  the  Caspian.  This  vast  gulf  communicates 
with  the  sea  by  a  narrow  mouth,  which,  in  its  most  contracted  part,  is  from 
150  to  160  yards  wide  ;  the  bar  will  not  allow  vessels  to  enter  which  draw 
more  than  5  feet  of  water.  A  current  coming  from  the  open  sea  is  always 
running  through  the  strait  with  a  speed  of  three  knots  an  hour.  The  west 
winds  accelerate  it,  and  the  winds  which  blow  in  an  opposite  direction  re- 
tard it,  but  it  never  flows  with  less  rapidity  than  a  knot  and  a  half.  All 
the  navigators  of  the  Caspian,  and  all  the  Turkoman  nomads  who  wander 
on  its  shores,  have  been  struck  with  the  unswerving,  inexorable  advance 
of  this  river  of  salt  water,  rolling  over  the  shoals  toward  a  gulf  which  even 
recently  none  had  ever  ventured  to  navigate.  In  the  view  of  the  natives 
this  inland  sea  could  be  nothing  but  an  abyss,  a  "black  gulf,"  as  is  express- 
ed by  the  name  Karaboghaz,  into  which  the  waters  of  the  Caspian  dive 


404  ^^^  EARTH. 

down  in  order  to  flow  through  subterranean  channels  into  the  Persian 
Gulf  or  the  Black  Sea.  It  is,  perhaps,  to  some  vague  rumors  as  to  the  ex- 
istence of  the  Karaboghaz  that  we  must  attribute  the  statements  of  Aris- 
totle about  the  strange  gulfs  in  the  Euxine,  in  which  the  waters  of  the 
Hyrcanian  Sea  bubble  up  after  having  flowed  hundreds  of  miles  through 
the  realms  of  Pluto. 

The  existence  of  this  current,  which  conveys  the  salt  waves  of  the  Cas- 
pian into  the  vast  Gulf  of  Karaboghaz,  is  nowadays  most  satisfactorily 
explained.  In  this  basin,  exposed  as  it  is  to  every  wind  and  the  most  in- 
tense summer  heat,  the  evaporation  is  considerable;  the  water  is  there- 
fore constantly  diminishing,  and  the  deficit  can  only  be  supplied  by  a 
continual  fresh  flow.  Investigations,  which  can  readily  be  made  in  the 
narrow  and  shallow  channel  of  the  Karaboghaz,  have  failed  to  ascertain 
the  existence  of  a  submarine  counter-current  conveying  back  to  the  Cas- 
pian the  Salter  water  of  the  gulf.  It  is  therefore  very  probable  that  it  is 
the  atmosphere  only  which  absorbs  the  water  brought  by  the  Caspian 
current;  but,  though  deprived  of  its  water  by  evaporation,  the  immense 
marsh  retains  the  salt ;  the  saline  matter  is  more  concentrated  in  it,  and 
the  water  is  moi*e  and  more  saturated  with  it  every  day.  Already,  it  is 
said,  no  animal  can  live  in  it ;  seals  which  used  to  frequent  it  are  no  longer 
found  there,  and  even  its  banks  are  devoid  of  all  agitation.  Layers  of 
salt  begin  to  be  deposited  on  the  mud  at  the  bottom,  and  the  sounding- 
line,  when  scarcely  out  of  the  water,  is  covered  with  saline  ciystals.  M. 
de  Baer  has  made  the  attempt  to  calculate  approximately  the  quantity  of 
salt  of  which  the  Caspian  is  every  day  deprived  for  the  benefit  of  the 
"black  gulf."  Taking  only  the  lowest  estimates  of  the  degree  of  saltness 
of  the  Caspian  water,  the  width  and  depth  of  the  channel,  and  the  speed 
of  the  current,  he  has  pi'oved  that  the  Karaboghaz  receives  daily  350,000 
tons  of  salt — that  is,  as  much  as  is  consumed  in  the  whole  Russia"  empire 
during  a  period  of  six  months.  If,  in  consequence  of  violent  storms,  or 
the  slow  action  of  the  sea,  the  bar  should  close  up  between  the  Caspian 
and  the  Karaboghaz,  the  latter  would  quickly  diminish  in  extent;  its 
banks  would  be  converted  into  immense  fields  of  salt,  and  the  sheet  of 
water  which  might  remain  in  the  centre  of  the  basin  would  become  only 
a  marsh.  Perhaps,  indeed,  it  would  disappear  altogether,  like  that  sea 
which  used  to  lie  between  Lake  Elton  and  the  River  Oural,  the  former 
existence  of  which  is  made  known  only  by  a  depression  in  the  ground  of 
about  79  feet  below  the  level  of  the  Caspian,  and  151  feet  below  that  of 
the  Black  Sea.  Like  a  tree  letting  fall  its  fruit  upon  the  ground,  the  Rus- 
sian Mediterranean  detaches  from  its  bosom  the  bays  and  gulfs  on  its 
coasts,  and  scatters  them  over  the  steppe  in  the  form  of  lakes  and  pools. 

The  comparative  observations  which  have  been  made  as  to  the  average 
level  of  the  Caspian  Sea  are  not  yet  numerous  enough  to  warrant  us  in 
admitting,  with  certain  geographers,  as  a  proved  fact,  that  there  is  a  con- 
stant diminution  of  the  water  in  this  inland  sea.  We  are  likewise  ignorant 
what  foundation  there  may  be  for  the  opinion  of  some  of  the  inhabitants 


THE  BUGORS  OF  THE   CASPIAN   SEA 


PL.  XIX. 


V>'  ^.un   of  Pan'« 


\ 


'-■:&.■      -ASTRAKHAN 


^^_,- --ysc- 


So 


of 


^ 


x>* 


^ 


iaf,^  bjr  fo-h«rd . 


HARPER  &c  BROTHERS.  NEW  YORK. 


•Bertfi 


afier  Ber  jdr&sio'. 


CASPIAN  SEA.  405 

of  the  coasts,  mentioned  by  Humboldt  in  his  Asie  Centrale^  according  to 
which  the  Caspian  Sea  experiences  a  succession  of  rises  and  falls  every 
twenty-five  Jo  forty-five  yeai*s.  It  seems,  however,  probable  that  the 
oscillations  in  its  level  are  of  no  great  importance,  and  that  the  quantity 
of  water  removed  by  evaporation  is  on  the  average  exactly  replaced  by 
the  liquid  mass  accruing  from  rivers  and  rain.  An  eqifilibrium  is  nearly 
established  between  the  supply  and  the  loss. 

There  is  one  point  which  is  certain,  that  at  the  epoch  when  the  Caspian 
Sea  was  separated  from  the  Euxine,  its  level  sank  in  a  comparatively 
rapid  way  on  account  of  the  excess  of  the  evaporation.  A  proof  of  this 
fact  may  be  seen  on  the  sides  of  the  rocks  which  were  once  washed  by  the 
waves  of  the  Caspian.  At  the  height  of  65  to  80  feet  above  the  present 
level,  of  the  water,  these  former  shoal-rocks  have  been  furrowed  out  into 
tooth-shaped  points  and  needles;  lower  down,  on  the  contrary,  the  rocks 
bear  no  trace  of  the  erosive  action  of  the  water,  evidently  because  the 
level  of  the  sea  sank  too  rapidly  to  allow  the  waves  sufficient  time  to  at- 
tack successfully  the  cliff  walls. 

The  innumerable  indentations  which  cut  into  the  shore  between  the 
mouths  of  the  Kouma  and  those  of  the  Oural,  and  principally  south  of  the 
Volga,  constitute  another  striking  instance  of  the  rapidity  with  which  the 
level  of  the  Caspian  must  have  sunk  after  the  sill  of  the  Isthmus  of 
Manytch  emerged  from  the  water.  For  a  space  of  more  than  248  miles 
the  shore  is  gashed  with  very  long  and  narrow  channels,  twelve,  twenty, 
and  even  thirty  miles  in  length,  and  throws  out  into  the  sea  a  multitude 
of  peninsulas,  which  are  prolonged  for  a  great  distance  into  the  water  by 
isles  likewise  disposed  in  parallel  ranges  and  separated  by  long  channels. 
These  tongues  of  land  form  a  kind  of  chain,  which  is  interrupted  here  and 
there  by  the  sea-water,  and  sink  by  successive  falls  from  isle  to  islet,  and 
from  islet  to  marsh.  The  thousands  of  channels  which  separate  these 
narrow  embankments  of  land  are  an  immense  labyrinth,  unexplored  even 
by  fishermen ;  it  requires  a  map  of  the  most  detailed  character  to  give 
any  idea  of  this  strange  swarm  of  isles,  islets,  channels,  and  bays. 

Tlie  bagors^  or  chains  of  hillocks  which  run  between  the  parallel  bays, 
and  farther  inland,  are  connected  with  the  level  ground  of  the  steppes, 
are  in  general  very  narrow,  their  length  varying  from  a  hundred  yards  to 
three  or  even  four  miles.  They  usually  rise  to  the  unpretending  eleva- 
tion of  26  to  30  feet ;  but  some  attain  double  this  height.  Seen  from  a 
balloon,  the  ensemble  of  the  b^igors  would  resemble  a  tract  of  marshy  land 
turned  up  by  a  gigantic  plowshare.  Immediately  to  the  west  of  the 
Volga,  the  limans,  or  furrows  which  separate  the  bugors,  are  always 
changed  into  rivers.  During  the  inundation  of  the  river,  the  current 
pours  into  these  channels  the  overflow  of  its  waters  charged  with  mud ; 
then,  after  the  flood  is  over,  the  sea  again  penetrates  them,  and  there  is 
thus  produced  in  these  channels  a  constant  backward  and  forward  motion 
between  the  sea  and  the  Volga.  Farther  to  the  south,  the  narrow  valleys 
of  the  limatis,  not  being  so  oflen  filled  up  by  the  flood-waters,  do  not,  in 


406  THE  EARTH. 

general,  present  a  continuous  sheet  of  water,  but  only  a  chain  of  lakes, 
separated  from  each  other  by  sandy  isthmuses. 

If  we  compare  the  whole  of  these  ranges  of  hillocks  to  a  border  of  fringe 
attached  to  the  continent,  we  shall  observe  that  these  fringes  spread  out 
somewhat  like  a  fan,  on  one  side  toward  the  north,  on  the  other  toward 
the  south.  They*  are  like  the  extremities  of  radii  diverging  from  a  com- 
mon centre  which  would  lie  in  the  depression  of  Manytch,  on  the  ledge 
which  separates  the  slopes  of  the  two  seas.  How  can  this  arrangement 
be  explained  except  by  the  fact  of  the  rapid  sinking  of  the  level  of  the 
Caspian  waters  hollowing  out  in  the  soft  soil  the  narrow  furrows  which  so 
astonish  us  ?  Thus,  on  the  muddy  banks  of  a  reservoir  when  the  sluice- 
gate is  opened,  small  limans  are  formed,  separated  by  bugors  in  miniature. 
A  very  remarkable  fact,  which  again  tends  to  confirm  the  result  of  M.  de 
Baer's  investigations,  is  that  all  the  bugors  of  the  Caspian  shore  are  strati- 
fied, and  the  superimposed  beds  assume  the  form  of  concentric  arches. 
The  strata  of  the  strongest  clay  ^re,  as  it  were,  the  nuclei  round  which 
are  deposited  the  earth  that  is  more  mingled  with  sand.  This  distribu- 
tion of  the  strata  is  owing  to  the  action  of  the  currents  of  water  which 
gave  to  the  bugors  their  present  appearance.  It  may,  in  fact,  be  readily 
understood  that  the  strata  of  clay  and  sand,  being  undermined  laterally  by 
the  water  running  down  the  channels,  bent  over  on  both  sides  toward  the 
currents  which  washed  their  bases ;  hence  arise  these  stratifications  in  the 
form  of  an  arch. 


DEAD  SEA.  407 


CHAPTER  LIX. 

THE    DEAD   SEA. — THE   SALT   LAKES   OF   ASIA   MENOB   AXD   THE    RUSSIAN 
feTEPPlES. — THE    GBEAT   SALT   LAKE. — THE   HELR'iR. 

Although  the  Caspian  is  the  largest  of  all  the  inland  seas,  the  Asphal- 
tite  Lake  is  in  some  respects  the  most  curious  on  account  of  its  position  in 
a  deep  fissure  of  the  earth,  many  hundreds  of  feet  below  the  level  of  the 
Mediterranean,  Since  Schubert  discovered,  at  the  beginning  of  the  cen- 
tury, this  single  instance  of  a  similar  depression,  it  has  been  ascertained  by 
exact  measurements  that,  over  an  area  of  nearly  186  miles,  the  whole  val- 
ley ascending  toward  the  base  of  Lebanon  and  lying  parallel  to  the  sea- 
shore of  Palestine  is  lower  than  the  ocean.  Below  the  small  Lake  of 
Ilouleh,  the  River  Jordan,  which  traverses  the  valley,  flows  into  a  cavity 
which  deep*ens  by  quickly  recurring  steps  below  the  ideal  sea-line.  The 
level  of  Lake  Asphaltites,  in  which  the  waters  of  the  river  are  lost,  is  1286 
feet  lower  than  that  of  the  sea.  The  greatest  depth  reached  by  the 
sounding-line  exceeds  984  feet,  and  is,  therefore,  2270  feet  below  the  level 
of  the  Mediterranean.  Thus  the  depression  into  which  the  Jordan  falls  is 
deeper  than  the  whole  extent  of  the  Adriatic  and  several  other  marine 
basins  in  communication  with  the  ocean.  Lake  Asphaltites,  however, 
does  not  merit  the  name  of  sea  from  its  depth  and  its  intense  saltness 
only ;  it  also  possesses  its  principal  current,  flowing  from  north  to  south, 
and  continuing  the  course  of  the  Jordan,  and  its  counter-currents  flowing 
on  both  sides  parallel  to  the  shore.*  The  surface  OT  the  Dead  Sea  exceeds 
460  square  miles ;  but,  a§  is  proved  by  the  horizontal  layers  of  gypseous 
marl  and  the  beds  of  salt  deposited  in  stages  on  the  slopes  of  the  sur- 
rounding mountains,  the  level  of  the  lake  was  formerly  much  higher  than 
it  is  at  present;!  ^^^  probably  the  water  filled  all  the  elongated  space 
comprehended  between  the  foot  of  Lebanon  and  the  entrance  to  Arabah 
at  the  north  of  the  Red  Sea.  The  drying  up  of  the  ancient  sea  of  the  Sa- 
hara, and  the  consequent  diminution  of  rains  and  increase  of  evaporation 
is,  perhaps,  the  cause  which  gradually  lowered,  century  after  century,  this 
ancient  sea,  called  so  appropriately  to  this  day,  the  "Dead  Sea." 

In  fact,  the  landscape  thoroughly  presents  an  aspect  of  death.  The 
rocks  are  bare;  nearly  every  spot  on  the  shores  is  sterile;  the  waters 
themselves  nourish  with  difficulty  but  a  few  living  beings  of  the  lowest 
order ;  the  fish,  crustaceans,  and  insects  brought  down  by  the  Jordan  and 
the  surrounding  mountain  torrents  immediately  die ;  aquatic  plants  are 
unable  to  grow.     Off  the  mouth  of  a  rivulet,  the  Wady-Mojeb,  small  fish 

*  Vignes,  Voyage  d Exploration  a  la  Mer  Mortc. 

t  Jj&rtet,  Bulletin  de  la  Sociiti  G^ologique  de  France,  vol.  xxii. 


408 


THE  EARTH. 


are  carried  as  far  as  a  point  in  the  lake  where  the  density  of  the  water  is 
1-115,  but  beyond  this  spot  they  inevitably  perish.     The  only  animals  that 


wT^^n^    T 


-r~i — z — » 


Fig.  165.  The  Dead  Sea  aud  the  Jordan. 


have  been  found  in  the  mud  at  the  bottom  are  some  species  of  foraminifera, 
classified  by  Eh renberg,  the  mici-ographer.  This  almost  complete  absence 
of  living  organisms  was  formerly  attributed  to  the  enormous  proportion 


DEAD  SEA.  409 


of  soa-salt  which  is  found  in  the  watei*  of  the  Dead  Sea.  This  proportion 
is,  in  fact,  very  considerable,  for  it  is  twice  as  great  as  that  in  the  Mediter- 
ranean ;  but  there  is,  on  the  border  of  the  lake,  a  small  pond,  the  water  of 
which  is  not  less  salt  than  that  of  the  Dead  Sea,  and  yet  a  large  quantity 
of  small  fish  live  in  it,  which  are  immediately  killed  by  an  immersion  for 
a  few  moments  in  Lake  Asphaltites.*  It  is,  then,  probably  chloride  of 
magnesium  and  bromine  which  render  the  waters  of  this  inland  sea  so 
sompletely  destructive  to  animal  life. 

Chemical  analyses  have  shown  that  the  matters  contained  in  the  Dead 
Sea  differ  greatly  from  those  of  sea-water,  not  only  in  proportion,  but  also 
in  number.  Thus  chloride  of  magnesium  is  found  in  this  lake  in  much 
greater  abundance  than  sea-salt  itself;  the  proportion  of  bromine  is  also 
most  extraordinary,  as  it  varies  from  less  than  15  to  more  than  67  thou- 
sandth parts  of  the  water.  On  the  other  hand,  iodine,  a  substance  the 
presence  of  which  is  so  characteristic  of  the  waters  of  the  ocean,  appears 
to  be  completely  wanting  in  the  water  of  the  Dead  Sea ;  neither  are  phos- 
phorus, silver,  caesium,  rubidium,  nor  lithium  found  in  its  water.  It  must 
be  concluded  that  the  Lake  Asphaltites  has  never,  since  its  formation,  con- 
stituted a  part  of  the  sea,  and  that  it  is  not,  as  was  long  supposed,  an  an- 
cient prolongation  of  the  Red  Sea,  separated  from  the  rest  of  this  gulf  by 
the  npheaving  of  the  entrance  of  Arabah.  Ehrenberg,  however,  had  al- 
ready come  to  this  conclusion  by  ascertaining  that  not  one  of  the  forami- 
nifera  found  in  the  mud  of  the  Dead  Sea  belongs  to  any  species  discovered 
in  the  lied  Sea.  M.  Lartet  thinks  that  the  chemical  substances  contained 
in  the  water  of  Lake  Asphaltites  proceed  from  thermal  springs  spouting 
out  on  the  shores,  and  especially  from  the  bed  of  the  lake.  One  fact  which 
tends  to  confirm  this  hypothesis  is,  that  the  quantity  of  bromine  increases 
with  the  depth  of  the  water;  it  is  at  984  feet  from  the  surface  that  the 
largest  proportion  of  this  substance  is  found.  The  fragments  of  bitumen 
which  float  on  the  surface  of  the  water,  and  have  gained  for  the  basin  the 
name  of  Lake  Asphaltites,  also  proceed  from  the  springs  in  its  bed.  As 
regards  the  saltness  properly  so  called,  it  must  have  naturally  Increased 
by  the  gradual  concentration  of  the  water.  When  the  latter  extended 
over  a  larger  surface  of  the  country,  the  proportion  of  sea-salt  dissolved  in 
*  .lArtet,  Bulletin  de  la  Sori€t€  G€olo<jique  de  France,  vol.  xxiii. 


410  THE  EARTH. 

the  liquid  mass  must  have  been  much  less.  When  the  sea  retires,  it  of 
course  leaves  a  saline  sediment;  but  this  sediment  is  conveyed  into  it 
partly  by  streams  and  by  the  Jordan  itself,  which  empties  into  the  lake 
about  90  cubic  yards  of  water  a  second  (?),  containing  6^  bushels  of  sea- 
salt.  At  the  present  time  the  water  of  the  Dead  Sea,  the  specific  gravity 
of  which  is  in  some  places  from  1"230  to  1'250,  has  almost  reached  the 
point  of  saturation  ;  it  deposits  saline  crystals  at  the  bottom,  and  only  dis- 
solves to  a  very  trifling  extent  the  base  of  a  clifl"  of  rock-salt  which  over- 
looks the  western  coast. 

All  the  great  lakes  of  Asia  Minor,  situated  at  different  altitudes  be- 
tween the  two  great  depressions  of  the  Dead  Sea  and  the  Caspian,  are 
likewise  rich  in  chemical  substances.  Lake  Van,  which  covers  an  area  of 
1544  square  miles,  especially  contains  sulphate  of  soda,  which,  during  the 
dry  season,  when  the  waters  are  low,  kills  all  the  fish  brought  into  it  by 
the  tributary  streams.  Lake  Urimiyeh,  still  more  extensive  than  Lake 
Van,  is  chiefly  remarkable  for  the  enormous  quantity  of  sea-salt  which  it 
holds  in  a  state  of  solution ;  in  this  respect  it  is  only  equaled  by  the  la- 
gunes  of  the  deserts  and  steppes,  where  the  salt  is  so  concentrated  that  it 
is  deposited  upon  the  bottom  in  thick  beds.  Of  this  kind  ts  Lake  Elton, 
to  the  northwest  of  the  Caspian.  The  bed  of  this  sheet  of  water  consists 
of  immense  layers  of  salt,  to  which  each  day  adds  a  fresh  sediment.  In 
winter,  the  rivulets  which  empty  themselves  into  this  small  closed  basin 
bring  a  certain  quantity  of  brine,  which  afterward  evaporates  during  the 
heat,  leaving  upon  the  soil  a  bed  of  crystals  several  inches  in  thickness. 
In  summer,  when  the  shores  are  not  covered  with  water,  they  appear  to 
extend  as  far  as  one  can  see,  like  an  immense  field  of  snow.  Every  year 
more  than  220,650,000  lbs,  of  salt  are  extracted  from  Lake  Elton,  and  yet 
the  saltness  of  its  waters  has  not  perceptibly  diminished. 

The  Great  Salt  Lake  of  America  is  another  Dead  Sea,  into  which  falls 
another  Jordan,  and,  by  a  strange  historical  coincidence,  the  Mormons 
have  established  themselves  upon  the  shores  of  this  very  lake ;  for  this 
sect  call  themselves  the  successors  of  the  Jews,  and  the  chosen  people  of 
the  New  World.  This  inland  sea,  the  real  shape  of  which  has  only  been 
known  since  1850,  by  means  of  the  explorations  of  Stansbury,  is  one  of  the 
most  remarkable  lacustrine  sheets  in  the  world;  it  is  not  less  than  248 
miles  in  cii'cumference,  but  its  depth  is  inconsiderable,  and  does  not  ex- 
ceed 32  feet ;  the  average  is  only  about  6  feet. 

The  degree  of  saltness  of  the  Great  Lake  varies  according  to  the  seasons 
and  the  duration  of  rains  and  drought ;  but  it  is  always  much  more  intense 
than  that  of  the  ocean.  In  fine  weather,  one  might  go  to  sleep  on  the 
waves  of  the  lake  without  fear  of  being  drowned ;  nevertheless,  it  is  very 
diflicult  to  swim  in  it  on  account  of  the  effort  which  must  necessarily  be 
made  in  order  to  keep  the  legs  below  the  surface.  A  single  droplet  fall- 
ing into  the  eye  causes  the  most  cruel  suffering,  and  the  water,  when  swal- 
lowed, causes  paroxysms  of  spasmodic  coughing.  Stansbury  doubts  if  the 
most  experienced  swimmer  could  escape  death  if  he  were  exposed  far 
from  the  shore  to  the  violence  of  the  waves  and  wind.     Although  the 


GREAT  SALT  LAKE.  411 

Great  Lake  only  contains  a  very  small  proportion  of  those  salts  s(f  destruc- 
tive to  animal  life  which  are  found  in  the  Dead  Sea,  yet  neither  fish  nor 
molluscs  exist  in  it ;  life  is  only  represented  by  sea-weed  of  the  Nostoc 
tribe,  and  by  a  small  worm  which  here  and  there  burrows  in  the  sand  of 
the  shores.  The  trout  which  are  carried  into  its  waters  by  the  Jordan 
perish  immediately.  Nevertheless,  the  surface  of  the  lake  affords  hospi- 
tality to  innumerable  flocks  of  gulls,  wild  geese,  swans,  and  ducks.  Whole 
armies  of  young  pelicans,  tended  by  their  old  lame  guardian-birds,  contem- 
plate the  waves  from  the  top  of  all  the  ledges  of  rock,  while  the  parents 
go  to  fish  in  the  Bear,  Weber,  and  Jordan  rivers,  all  of  which  abound  in 
|ish.  Not  a  tree  grows  upon  the  shores  of  the  lake  nor  in  the  adjacent 
plains;  the  only  vegetation  to  be  seen  far  and  wide  is  tufts  oi Artemisia,  and 
other  plants  which  delight  in  a  soil  impregnated  with  saline  substances. 

The  line  of  separation  between  the  water  and  dry  ground  is  generally 
undecided ;  it  is  impossible  to  tell  where  the  shore  begins  or  where  the 
lake  ends,  as  so  much  of  the  shore  presents  muddy  banks  upon  which  the 
water  spreads  in  thin  sheets  and  drifts  about  its  flaky  foam.  Higher  up 
the  shore  the  mud  dries  in  the  sun  and  peels  off  in  scales,  which  have  the 
appearance  of  leather ;  sulphureous  exhalations  escape  from  cracks  in  the 
soil,  and  diffuse  an  intolerable  odor  in  the  air.  On  the  western  side,  vast 
plains,  nearly  as  level  as  the  surface  of  the  water,  extend  between  the  lake 
and  a  range  of  distant  mountains.  During  some  of  the  summer  months, 
these  plains,  which  are  crossed  by  rivulets  loaded  with  chemical  substances, 
are  covered  by  an  immense  sheet  of  crystalline  salt  split  up  into  innumer- 
able furrow^produced  by  contraction  of  the  soil.  Whenever  rain  falls,  or 
even  when  the  air  is  simply  charged  with  moisture,  the  salt  becomes  deli- 
quescent, and  nothing  is  to  be  seen  but  an  expanse  of  blackish  clay,  into 
which  beasts  of  burden  sink  at  every  step  they  make. 

Formerly  the  Great  Salt  Lake,  like  all  other  inland  seas  saturated  with 
salt,  spread  over  a  much  more  considerable  area.  The  parallel  basins  of 
the  plateau  of  Utah,  and  the  lateral  valleys  which  run  into  them,  were  the 
gulfs,  bays,  and  straits  of  the  inland  sea.  At  a  great  height  above  the 
present  level  of  the  lake,  the  former  alluvial  shores  and  cliffs  surround  the 
valleys  with  their  concentric  rings  traced  upon  the  sides  of  the  mountains. 
Even  in  the  plains  some  distance  off,  the  surface  of  which  exhibits  a  thin 
bed  of  vegetable  earth,  the  substratum  is  lake-clay  saturated  with  sea-salt 
and  the  sulphates  of  lime  and  magnesia.  Agriculture,  therefore,  is  nearly 
impossible  upon  these  ancient  lacustrine  beds.  In  the  earliest  years  of 
colonization  the  damp  and  virgin  earth  still  produced  crops  to  some  ex- 
tent, but  subsequently  the  vegetable  soil  has  lost  its  nutritive  elements, 
and  the  clayey  substratum,  coming  in  contact  with  the  roots  of  the  plants, 
withers  them  up  by  means  of  its  acrid  properties. 

Similar  causes  to  those  which  led  to  the  contraction  of  the  Caspian  and 
the  Dead  Sea  have  const-antly  tended  to  diminish  the  waters  of  Lake  Utah, 
and  also  to  saturate  them  with  an  enormous  quantity  of  salt.  The  Great 
Basin  is  separated  from  the  Pacific  by  high  mountains  of  comparatively 
recent  formation,  which  arrest  the  progress  of  the  clouds,  and  prevent  them 


^12  THE  EABTH. 

from  pouring  upon  tlie  plateau  the  moisture  derived  from  the  sea.  On 
the  other  hand,  the  evaporation  is  very  considerable  upon  these  high, 
rocky,  and  bare  plains,  and  the  winds  which  traverse  them  are  but  little 
impeded  from  carrying  the  vapors  outside  the  basin  of  Utah.-  In  conse- 
quence of  this  constant  loss,  the  level  of  the  Great  Lake  is  become  lower, 
the  streams  are  dried  up,  the  spi'ings  are  exhausted,  and  the  salt  has  con- 
centrated more  and  more  in  the  water.  It  is  probable  that,  at  the  present 
time,  an  equilibrium  is  at  length  established  between  the  annual  fall  of 
snow  and  rain  and  the  mists  which  rise  from  the  surface  of  the  diminished 
lake.  Since  the  establishment  of  the  Mormons  in  the  territory  of  Utah, 
the  level  of  the  lake  has  alternately  risen  and  sunk.* 

The  various  phenomena  which  take  place  in  the  waters  of  the  Great  Salt 
Lake,  as  well  as  in  those  of  the  Caspian,  Lake  Urimiyeh,  and  the  Dead  Sea, 
are  also  produced  in  a  multitude  of  other  lacustrine  basins  of  less  impor- 
tance, with  all  the  variations  caused  by  the  difference  of  climate,  the  na- 
ture of  the  soil,  and  the  composition  of  the  water.  But  as  a  great  num- 
ber of  these  lakes  are  situated  in  regions  destitute  of  rain,  and  owe  their 
saltness  to  the  copious  evaporation  which  has  abstracted  so  large  a  part 
of  their  waters,  they  are,  in  consequence  of  this  diminution,  of  very  small 
area,  and  have  become  converted  into  lagoons  and  marshes.  Sometimes, 
indeed,  they  are  reduced  to  surfaces  which  are  alternately  muddy  and 
white  with  salt,  when  they  have  been  either  wetted  by  some  casual  rains 
or  dried  up  by  the  solar  rays.  As  a  type  of  these  salt-tracts  may  be  men- 
tioned the  steppes  of  Huiduck  in  the  Ponto-Caspian  isthmus,  and  the  Chott 


880.000  ^^^Sa 


s       IS 


Fig.  ICT.  Lakes  of  Huiduck. 

Melr'ir,  a  range  of  marshes  which  stretch  from  east  to  west,  over  a  length 
of  more  than  186  miles  to  the  south  of  Djebel  Aouress,  formerly  commu- 
nicating with  the  Gulf  of  Great  Syrtes  by  the  Strait  of  Gabes,  at  present 
choked  up  by  sand.f  These  marshes  are  separated  one  from  another  by 
isthmuses  and  islets  of  dry  ground,  and  extend  at  unequal  levels  to  95, 
118, 128,  213,  249,  and  even  279  feet  below  the  sea.J  During  the  rainy 
season  they  ai-e  sheets  of  shallow  water,  which  spread  far  and  wide  into 
the  plains;  during  the  dry  season  they  are  fields  of  salt,  over  which  the 
mirage  throws  its  illusions. 

*  Fremont,  Stansburv,  Jules  Remy,  Engelmann. 

t  Vide  below,  the  chapter  on  "  Ujiheavals  and  Depressions." 

X  Duboeq.  Memoire  sur  le  Zihan  et  tOtted-R'ir. 


MARSHES,  413 


CHAPTER  LX. 

MARSHES. — SWAM^    OP   NORTH    AMERICA. — PEAT-BOGS.  —  UNHEALTHINESS 

OF   MARSHES. 

Marshes  proper  are  shallow  lakes,  the  waters  of  which  are  either  stag- 
nant or  actuated  by  a  very  feeble  current;  they  are,  at  least  in  the  tem- 
perate zone,  filled  with  rushes,  reeds,  and  sedge,  and  are  often  bordered  by 
trees,  which  love  to  plunge  their  roots  into  the  muddy  soil.  In  the  trop- 
ical zone  a  large  number  of  marshes  are  completely  hidden  by  multitudes 
of  plants  or  forests  of  trees,  between  the  crowded  trunks  of  which  the 
black  and  stagnant  water  can  only  here  and  there  be  seen.  Marshes  of 
this  kind  are  inaccessible  to  travelers,  except  where  some  deep  channel, 
Avinding  in  the  midst  of  the  chaos  of  verdure,  allows  boats  to  attempt  a 
passage  between  the  water-lilies,  or  under  some  avenue  of  great  trees  with 
their  long  garlands  of  creepers  waving  in  the  shade.  Whatever  may  be 
the  climate,  it  would,  however,  be  impossible  to  draw  any  distinction,  even 
the  most  vague,  between  lakes  and  marshes,  as  the  level  of  these  sheets  of 
water  oscillates  according  to  the  seasons  and  years,  and  as  the  greater 
number  of  lakes,  principally  those  of  the  plains,  terminate  in  shallow  bays 
which  are  perfect  marshes.  Some  very  important  lacustral  basins,  among 
others  Lake  Tchad,  one  of  the  most  considerable  in  all  Africa,  are  entirely 
surrounded  by  swamps  and  inundated  ground,  which  prohibit  access  to  the 
lake  itself,  and  prevent  its  true  dimensions  from  being  known. 

In  like  manner,  a  portion  of  the  course  of  many  rivers  traverses  low  re- 
gions in  which  marshes  are  formed,  either  temporary  or  permanent,  the 
uncertain  limits  of  which  change  incessantly  Avith  the  level  of  the  current. 
The  borders  of  great  water-courses,  when  left  in  their  natural  state,  are 
the  localities  in  which  these  marshy  reservoirs  principally  exist,  which,  in 
the  absence  of  basins  and  artificial  weirs,  are  of  very  great  importance  to 
the  regulation  of  the  fluviatile  discharge.  The  most  remarkable  marshes 
of  this  kind  are  perhaps  those  crossed  by  the  Paraguay  and  several  of  its 
tributaries ;  they  consist  of  wet  prairies  and  interminable  sheets  of  water, 
which  stretch  away  like  a  sea  from  one  horizon  to  the  other.  They  have 
received  the  names  of  Lakes  Xarayes,  Pantanal,  etc.  Farther  south,  cer- 
tain tributaries  of  the  Parana,  the  Maloya,  the  Batel,  and  the  Sarandi, 
which  cross  the  State  of  Corrientes  from  northeast  to  southwest,  are  noth- 
ing but  wide  marshes,  the  water  of  which  ovei-flows  slowly  across  the  grass 
on  the  irapei'ceptible  slope  of  the  territory.  There  is,  indeed,  one  of  these 
marshes,  the  Laguna  Bera,  which  drains  simultaneously  into  the  two  great 
rivers  of  Parana  and  Uruguay.  These  permanent  inundations,  however, 
can  not  fail  to  disappear,  sooner  or  later,  before  the  encroachments  of  cul- 
tivation. 


414 


THE  EARTH. 


Fig.  168.  Salt  Marshes  of  Paraguay. 

In  the  same  way  as  the  low  river-shores  are  frequently  converted  into 
marshes,  vast  extents  of  the  sea-coasts  when  but  slightly  inclined  are  also 
covered  over  by  marshes,  which  are  generally  separated  from  the  main  sea 
by  tongues  of  sand  gradually  thrown  up  by  the  waves.  In  these  marshes, 
most  of  which  once  formed  a  part  of  the  sea  and  still  mark  its  ancient  out- 
line, the  water  presents  the  most  varied  proportions  of  saline  admixture. 
In  some  places,  when  evaporation  is  very  active,  the  liquid  is  much  more 
salt  than  the  sea  itself;  but  in  other  spots  the  marsh,  fed  by  fresh  water 
which  comes  from  the  interior,  is  scarcely  brackish.  The  saltness  of  the 
water,  however,  constantly  changes  in  all  parts  o!  the  marsh,  according  to 
the  alternations  of  flow  and  ebb,  and  of  rainy  and  dry  weather.  These  half 
dried-up  bays  are  rarely  deep  enough  to  allow  of  large  vessels  sailing  in 
them,  and  their  banks  are  generally  overrun  by  the  most  luxuriant  veg- 
etation. The  shore  constantly  keeps  gaining  upon  them,  and  thus  tends 
to  the  increase  of  the  main  land. 

The  coasts  Avhich  surround  the  Caribbean  Sea  and  the  Gulf  of  Mexico, 
and  also  the  Atlantic  shores  of  North  America  from  the  point  of  Florida 
to  the  mouth  of  the  Chesapeake,  are  bordered  by  a  very  large  number  of 
marine  marshes,  forming  a  continued  series  over  hundreds  and  thousands 
of  miles  in  length.  In  this  immense  series  of  coast-marshes  all  kinds  of 
vegetation  seem  to  flourish,  and  threaten  to  get  the  better  of  the  mud 
and  water,  and  to  convert  them  into  terra 'Jirma.  To  the  south,  upon  the 
shores  of  Columbia  and  Central  America,  the  mangroves  and  other  trees 
of  like  species  plunge  the  terminal  points  of  their  aerial  roots  deep  into 
the  mud,  crossing  and  recrossing  in  an  arch-like  form,  and  retaining  all  the 
debris  of  plants  and  animals  under  the  inextricable  net-work  of  their  natu- 
ral scaffoldings.     The  shores  of  the  Gulf  of  Mexico,  in  Louisiana,  Georgia, 


SWAMFS.—QVAKIN6-B06S. 


415 


Fis.  109.  Marshes  of  Corrieutes. 


and  Floiida,  are  bordered  by  cypress  swamps,  or  forests  of  cypress  ( Cu- 
pressus  disticha) ;  these  strange  trees,  the  roots  of  which,  entirely  buried, 
throw  out  above  the  layer  of  water  which  covers  the  soil  multitudes  of 
little  cones,  the  business  of  which  is  to  absorb  the  air.  For  millions  of 
acres  nearly  all  the  marshy  belt  along  the  sea-shore  is  nothing  but  an  im- 
mense cypress  swamp,  with  trees  bare  of  leaves,  and  fluttering  in  the  wind 
their  long  hair-like  fibres  of  moss.  Here  and  there  the  trees  and  muddy 
soil  give  place  to  bays,  lakes,  or  quaking-meadows,  formed  by  a  carpet  of 
grass  lying  upon  a  soil  of  wet  mud,  or  even  upon  the  hidden  water.  In 
Brazil  these  ouoyant  beds  of  vegetation  are  frequently  met  with,  and  the 
significant  name  oitremendal  has  been  given  to  them :  in  Ireland  these  are 
calltMl  "  quaking-bog^."  The  least  movement  of  the  traveler  who  ventures 
upon  them  makes  the  soil  tremble  to  some  yards'  distance. 

To  the  north  of  Florida,  in  the  Carolinas  and  Virginia,  the  belt  of  cypress 
swamps  continue;  but  in  consequence  of  the  change  of  climate  and  vege- 
tation, the  quaking- meadows  are  gradually  converted  into  ])eat-mosses. 


416  THE  EARTH. 

Evaporation  being  much  less  active  in  these  countries  than  in  those  situ- 
ated farther  to  the  south,  and  the  dry  season  being  much  less  prolonged, 
the  water  arising  from  rain  and  inundation  remains — as  if  in  the  pores  of 
an  immense  sponge — in  all  the  interstices  of  the  entangled  mass  of  mosses, 
SpJiagnum^  Confervm^  and  other  aquatic  plants.  The  whole  marsh  swells 
toward  the  centre,  because  the  droplets,  divided  by  innumerable  stalks, 
can  not  spread  out  laterally,  and  are  drawn  by  capillary  attraction  into 
the  fresh  beds  of  plants  which  are  formed  above  the  older  ones.  The  sur- 
face of  the  marsh  is  incessantly  renewed  by  a  carpet  of  green  vegetation, 
while  below,  the  dead  plants,  deprived  of  air,  carbonize  slowly  in  the 
moisture  which  surrounds  them :  these  are  the  beds  of  peat  which  form 
upon  the  ground  just  as  the  layers  of  coal  were  formed  in  previous  geo- 
logical epochs. 

On  the  southern  side,  the  first  great  peat-bog  of  a  well-defined  character 
is  the  "  Dismal  Swamp,"  which  extends  along  the  frontiers  of  North  Car- 
olina and  Virginia.  This  spongy  mass  of  vegetation  rises  10  feet  above 
the  surrounding  land.  In  the  centre,  and,  so  to  speak,  upon  the  summit 
of  the  marsh,  lies  Lake  Drummond,  the  clear  water  of  which  is  colored 
reddish-brown  by  the  tannin  of  the  plants.  A  canal,  which  crosses  the 
Dismal  Swamp  to  connect  it  with  the  adjacent  streams,  is  obliged  to  make 
its  way  along  the  marsh  by  means  of  locks.  To  the  north  of  Virginia 
l^eat-bogs  proper  become  more  and  more  numerous ;  and  in  Canada,  Lab- 
rador, etc.,  they  cover  vast  expanses  of  country.  All  the  interior  of  the 
island  of  Newfoundland,  inside  the  inclosure  formed  by  the  forests  on  the 
shore,  is  nothing  but  a  labyrinth — a  great  part  of  which  is  still  unknown 
— of  lakes  and  peat-bogs;  even  on  the  sides  of  the  hills  there  are  marshes 
on  so  steep  an  incline  that  the  water  from  them  would  disappear  and  run 
off  in  a  stream  if  it  was  not  stopped  by  the  thick  carpet  of  plants  which  it 
saturates.  Many  a  large  peat-bog  w^ich  may  be  crossed  dry-shod  contains 
more  water  than  many  lakes  filling  a  hollow  of  the  valley  with  deep  water. 

Opposite  Newfoundland,  on  the  other  side  of  the  Atlantic,  Ireland  is 
hardly  less  remarkable  for  the  enormous  development  of  its  peat-mosses  or 
bogs.  These  tracts  of  saturated  vegetation,  in  which  Sjyhagnum  palustre 
predominates,  comprehend  nearly  two  and  a  half  millions  of  acres — the 
seventh  part  of  the  whole  island.  The  inhabitants  cpntinue  to  extract 
from  them,  every  year,  immense  quantities  of  fuel.  The  spaces  left  by  the 
spade  in  the  vegetable  mass  are  gradually  filled  up  again  by  new  layers. 
After  a  certain  number  of  years,  which  vary  according  to  the  abundance 
of  rain,  the  depth  of  the  bed  of  water,  the  force  of  vegetation,  and  the  slope 
of  the  soil,  the  turf  "  quarry"  is  formed  anew.  In  Ireland  it  generally 
takes  about  ten  years  to  entirely  fill  up  again  the  trenches,  measuring 
from  nine  to  thirteen  feet  in  depth,  which  are  made, in  the  bogs  on  the 
plains,  when  a  fresh  digging  of  turf  may  be  commenced.  In  Holland, 
crops  of  this  fuel  may  be  gathered,  on  an  average,  every  thirty  years. 
In  other  peat-moss  distiicts  the  period  of  regeneration  lasts  forty,  fifty, 
and  even  a  hundred  years.     In  France,  on  the  borders  of  the  Seugne 


PEATB008.  417 

(Charente-Inferieure),  it  has  been  ascertained  that  ditches  5  feet  deep  and 
nearly  7  feet  wide  are  completely  obstructed  by  vegetation  after  the  lapse 
of  twenty  years.  As  for  the  beds  of  peat  which  carpet  the  sides  of  moun- 
tains, they  take  centuries  to  form  afresh. 

As  every  thing  in  nature  is  continually  changing  and  modifying,  peaty 
marshes,  like  lakes,  are  all  either  in  a  period  of  increase  or  a  period  of 
decay — some  form  while  others  disappear.  Independently  of  the  action 
exercised  by  the  labor  of  man,  the  vegetation  of  peat-bogs  may  cease  to 
be  produced  in  any  basin  either  because  the  water  flows  away  naturally 
through  some  wide  outlet  'after  the  heavy  rains,  or  because  some  river,  by 
changing  its  course,  has  exhausted  or  immoderately  swollen  the  mass  of 
water  necessary  to  the  nourishment  of  the  peat ;  or,  again,  because  the 
rain,  becoming  either  more  rare  or  more  frequent,  has  dried  up  the  basin, 
or  converted  it  into  an  inundated  marsh ;  lastly,  the  sinking  or  upheaving 
of  the  soil  may  also,  according  to  the  various  conditions  of  the  relief  of 
the  country,  be  the  cause  of  the  disappearance  of  the  Flora  of  the  peat- 
bogs. The  same  causes,  acting  in  contrary  directions,  give  rise  to  and 
increase  these  enonj^ous  masses  of  plants  swollen  with  water.  In  Ireland, 
the  Low  Countries,  the  north  oFGermany  and  Russia,  heaps  of  trunks  of 
former  forest-trees — oaks,  beech,  alder,  and  other  trees — are  frequently  dis- 
covered, which  by  their  decay  have  made  way  for  the  peat-mosses.  The 
Sphagnum,  too,  often  takes  possession  of  ground  of  which  man  had  pre- 
viously made  himself  master,  and  in  many  places  roads,  remains  of  build- 
ings, and  other  vestiges  of  human  labor  are  found  below  the  modern  bed 
of  vegetation  by  which  they  are  now  covered.  Certain  peat-bogs  in  Den- 
mark and  Sweden  may  be  considered,  on  account  of  the  curiosities  which 
have  been  found  in  them,  as  perfect  natural  museums,  in  which  the  relk 
of  the  civilization  of  ancient  nations  have  been  preserved  for  the  save 
of  our  own  day.  ' 

The  air  above  the  peat-mosses  of  Ireland  and  other  countries  in  the  world 
is  not  often  unhealthy,  either  because  the  heat  is  not  sufficient  to  develop 
miasma,  or  else  because  the  vegetation,  by  absorbing  the  water  into  its 
spongy  mass,  impedes  the  corruption  of  the  liquid,  and  produces  a  consid- 
erable quantity  of  oxygen.  Farther  south,  the  peat-mosses,  which  are  in- 
termixed with  pools  of  stagnant  water,  and  especially  marshes  properly 
so-called,  generate  an  impure  air,  which  spreads  fever  and  death  over  the 
surrounding  country.  Unless  marshes  are  surrounded  with  dense  forests, 
which  arrest  the  dispersion  of  the  gases,  the  latter  exercise  a  most  injurious 
influence  on  the  general  salubrity  of  rtie  district;  for  during  dry  weather, 
a  vast  area  of  the  bed  of  the  marshes  becomes  exposed,  and  the  heaps  of 
organic  debris  lying  on  the  bottom  decompose  in  the  heat  and  infect  the 
whole  atmosphere.  The  average  of  life  is  much  shorter  in  all  marshy 
countries  than  in  the  adjacent  regions  which  are  invigorated  by  running 
water.  In  Brescia,  Poland,  in  the  marshes  of  Tuscany,  and  in  the  Roman 
plains,  the  wan  and  livid  complexion  of  the  inhabitants,  their  hollow  eyes, 
and  their  feverish  skin,  announce  at  first  sight  the  vicinity  of  some  centre 

Dd 


418  THE  EARTH. 

of  infection.  There  are  some  marshes  in  the  torrid  zone  where  the  de- 
composition of  organic  remains  goes  on  with  a  much  greater  rapidity 
than  in  temperate  climates ;  no  one  can  venture  on  the  edges  of  these 
districts  without  peril  to  his  life.  As  Frcebel  ascertained  in  his  journey 
across  Central  America,  the  miasma  is  occa'feionally  produced  in  such  abun- 
dance that  not  only  can  it  be  smelt,  but  a  distinct  impression  of  it  is  left 
upon  the  palate.  One  of  the  most  important  works  of  civilization  is  to 
deal  with  these  unwholesome  regions,  which  are  still,  as  it  were,  unde- 
cided between  land  and  water,  and  to  render  them  fit  for  cultivation  and 
to  be  the  abode  of  man. 


PART  IV. 
SUBTERRANEAN  FORCES. 


CHAPTER  LXL 

ERUPTION    OF    ETNA    IN    THE    YEAR    1865. — MUTUAL    DEPENDENCE    OF    ALL 
TERRESTRIAL   PHENOMENA. 

The  Greek  mythology,  harmonizing  in  this  i-espect  with  the  ideas  of 
most  nations  which  were  acquainted  with  volcanoes,  attributed  to  these 
mountains  an  origin  altogether  independent  of  the  forces  which  are  in  ac- 
tion on  the  surface  of  the  ground.  According  to  the  views  of  the  Hel- 
Jenes,  water  and  fii'e  were  two  distinct  elements,  and  each  had  its  separate 
domain,  its  genii,  and  its  gods.  Neptune  reigned  over  the  sea ;  it  was  he 
that  unchained  the  storms  and  caused  the  waves  to  swell.  The  tritons 
followed  in  his  train ;  the  nymphs,  sirens,  and  marine  monstere  obeyed 
his  orders,  and  in  the  mountain  valleys,  the  solitary  naiads  poured  out  t<) 
his  honor  the  murmuring  water  from  their  urns.  In  the  dark  depth  of 
unknown  abysses  was  enthroned  the  gloomy  Pluto;  at  his  side  Vulcan, 
surrounded  by  Cyclops,  forged  thunderbolts  at  his  resounding  anvil,  and 
from  their  furnaces  escaped  all  the  flames  and  molten  matter  the  appear- 
ance of  which  so  appalled  mankind.  Bet.ween  the  gods  of  water  and  of 
fire  there  was  nothing  in  common,  except  that  both  were  the  sons  of 
Chronos,  that  is,  of  Time,  which  modifies  every  thing,  which  destroys  and 
renews,  and,  by  its  incessant  work  of  destruction,  makes  ready  a  place  for 
the  innumerable  germs  of  vitality  which  crowd  on  the  threshold  of  life. 

Even  in  our  days,  the  common  opinion  is  not  much  at  variance  with  these 
mythological  ideas,  and  volcanic  phenomena  are  looked  upon  as  events 
of  a  character  altogether  different  from  other  facts  of  terrestrial  vitality. 
The  latter,  the  sudden  changes  of  which  are  visible  and  easily  to  be  ob- 
served, are  justly  considered  to  be  owing  principally  to  the  position  of  the 
earth  in  respect  to  the  sun  and  th^lternations  of  light  and  darkness,  heat 
and  cold,  dryness  and  moisture,  wmch  necessarily  result.  As  regards  vol- 
canoes, on  the  contrary,  an  order  of  entirely  distinct  facts  is  imagined, 
caused  by  the  gradual  cooling  of  the  planet. or  the  unequal  tides  of  an 
ocean  of  lava  and  fire.  Certainly,  the  eruptions  of  ashes  and  incandes- 
.  cent  matter  have  not  revealed  the  mystery  of  their  formation,  and  in 
this  respeq|  numerous  problems  still  remain  unsolved  by  scientific  men. 
Nevertheless,  the  facts  already  known  warrant  us  in  asserting  that  volcan- 


420  T^^  EARTH. 

ic  crises  are  connected,  like  all  other  planetary  phenomena,  with  the  gen- 
eral causes  which  determine  the  continual  changes  of  continents  and  seas, 
the  efosion  of  mountains,  the  courses  of  rivers,  winds,  and  storms,  the 
movements  of  the  ocean,  and  all  the  innumerable  modifications  which  are 
taking  place  on  the  globe.  If,  some  day,  we  are  to  succeed  in  pointing 
out  exactly  and  plainly  how  volcanoes  likewise  obey,  either  partially  or 
completely,  the  system  of  laws  which  govern  the  exterior  of  the  globe, 
the  first  and  most  important  requisite  is  to  observe  with  the  greatest 
care  all  the  incidents  of  volcanic  origin.  When  all  the  premonitory  signs 
and  all  the  products  of  eruptions  shall  have  been  perfectly  ascertained 
and  duly  classified,  then  the  glance  of  science  will  be  on  the  point  of  pen- 
etrating into,  and  duly  reading,  the  secrets  of  the  subterranean  abysses 
where  these  marvelous  convulsions  are  being  prepared. 

The  last  great  eruption  of  Etna,  that  central  pyramid  of  the  Mediterra- 
nean, which  the  ancients  named  the  "  Umbilicus  of  the  world,"  is  one  of 
the  most  magnificent  examples  which  can  be  brought  forward  of  volcanic 
phenomena ;  and  as  it  has,  moreover,  been  studied  most  precisely  and 
completely,  it  well  deserves  to  be  described  in  some  detail. 

The  explosion  had  been  heralded  for  some  long  time  by  precursory 
signs.  In  the  month  of  July,  1863,  after  a  series  of  convulsive  movements 
of  the  soil,  the  loftiest  cone  of  the  volcano  opened  on  the  side  which  facaP 
the  south.  The  incandescent  matter  descended  slowly  over  the  plateau 
on  which  stands  the  "  Maison  des  Anglais ;"  and  this  building  itself  was 
demolished  by  the  lumps  of  lava  which  were  hurled  from  the  mouth  of 
the  crater.  In  some  places  heaps  of  ashes  several  yards  thick  covered  the 
slopes  of  the  volcano.  After  t"his  first  explosion,  the  mountain  never  be- 
came completely  calm;  numerous  fissures,  which  opened  on  the  outer 
slopes  of  the  crater,  continued  to  smoke,  and  the  hot  vapor  never  ceased 
to  jet  out  from  the  summit  in  thick  eddies.  Often,  indeed,  during  the 
night,  the  reflection  of  the  lava  boiling  up  in  the  central  cavity  lighted 
up  the  atmosphere  with  a  fiery  red.  The  liquid,  being  unable  to  rise  to 
the  mouth  of  the  crater,  pressed  against  the  external  walls  of  the  vol- 
cano, and  sought  to  find  an  issue  through  the  weakest  point  of  the  crust 
by  melting  gradually  the  rocks  that  opposed  its  passage.  Finally,  in  the 
night  of  the  30th  to  the  31st  of  January,  1865,  the  wall  of  the  crater  yield- 
ed to  the  pressure  of  the  lava ;  some  subterranean  roaring  was  heai-d ; 
slight  agitations  aflTected  the  whole  of  the  eastern  part  of  Sicily,  and  the 
ground  was  rent  open  for  the  length  of  a  mile  and  a  half  to  the  north  of 
Monte  Frumento,  one  of  the  secondary  eones  which  rise  on  the  slope  of 
Etna.  Through  this  fissure,  which  opened  on  a  gently-inclined  plateau, 
the  pent-up  lava  violently  broke  through  to  the  surface. 

The  fissure  which  opened  on  the  side  of  the  mountain,  and  could  be 
easily  followed  by  the  eye  to  a  point  about  two-thirds  of  tlie  height  of 
Monte  Frumento,  in  the  direction  of  the  terminal  crater  of  ^tna,  seems 
to  have  vomited  out  lava  but  for  a  very  few  hours.  Being  somi  obstruct- 
ed by  the  snow  and  the  debris  of  the  adjacent  sloi)es,  it  ceased  to  retain 


EJiUmON  OF  ETXA  IN  1«65. 


421 


its  communication  with  the  interior  q^he  mountain,  and  now  resembled 
a  kind  of  furrow,  as  if  hollowed  out  by  the  rain-water  on  the  side  of  the 
cone.  On  the  Slst  of  January  all  the  volcanic  activity  of  the  crevice  was 
concentrated  on  the  gently  inclined  plateau  which  extends  at  the  base  of 
Monte  Frumento,  in  the  midst  of  which  several  new  hillocks  made  their 
appearance.  On  the  lower  prolongation  of  the  line  of  fracture,  all  the 
j)henomena  of  the  eruption  properly  so-called  were  distributed  in  a  per- 
fectly regular  way.  Six  principal  cones  of  ejection  were  raised  above  the 
crevice,  and  gradually  increased  in  size,  owing  to  the  debris  which  they 
threw  out  of  their  craters ;  these,  gradually  mingling  their  intervening 
slopes,  and  blending  them  one  with  another,  absorbed  in  succession  other 
smaller  cones  which  had  been  formed  by  their  sides,  thus  reaching  a 
lieight  of  nearly  300  feet.     Soon  after  the  commencement  of  the  eruption 


Fig.  no.  Coulie  of  Monte  Fnimento. 

the  two  upper  craters,  standing  close  together  on  an  isolated  cone,  vom- 
ited nothing  but  lumps  of  stone  and  ashes,  while  jets  of  still  liquid  lava 
were  emitted  by  the  lower  craters,  which  were  arranged  in  a  semicircle 
round  a  sort  of  funnel-shaped  cavity.  In  consequence  of  the  specific 
gravities  of  the  substances  evacuated,  a  regular  division  of  labor  took 
l)lace  between  the  various  points  of  the  crevice.  The  projectiles  which 
had  solidified  the  triturated  debris^  and  the  more  or  less  porous  frag- 
ments which  floated  on  the  top  of  the  lava,  made  their  escape  by  the 
liigher  orifices ;  but  the  liquid  mass,  being  heavier  and  more  compact, 
could  only  burst  forth  from  the  ground  by  the  mouths  opening  at  a  less 
elevation. 

Two  months  after  the  commencement  of  the  eruption,  the  cone  which 
was  the  nearest  to  Frumento  ceased  to  send  out  either  scorisB  or  ashes. 
The*pipe  of  the  crater  was  filled  up  with  debris,  and  the  internal  activity 
was  revealed  by  vapors  either  of  a  sulphurous  character  or  charged  with 


422  ^^^  EARTH. 

hydrochloric  acid.  These  rose  li|||  smoke  from  the  slope  of  the  hillock. 
The  second  cone,  situated  on  a  lower  part  of  the  fissure,  remained  in  di- 
rect communication  with  the  central  flow  of  lava;  but  it  was  not  in  a 
constant  state  of  eruption,  and  rested  after  each  efibrt  as  if  to  take  breatli. 
A  crash  like  that  of  thunder  was  the  forerunner  of  the  explosion ;  clouds 
of  vapor,  rolling  in  thick  folds,  gray  with  ashes,  and  furrowed  with  stones, 
darted  out  from  the  mouth  of  the  volcano,  darkening  the  atmosphere,  and 
throwing  their  projectiles  over  a  radius  of  several  hundreds  of  yards 
round  the  hillock.  Then,  after  having  discharged  their  burdens  of  debris, 
the  dark  clouds,  giving  way  before  the  pressure  of  the  winds,  mingled  far 
and  wide  with  the  mists  on  the  horizon.  The  lower  cones,  which  rose 
immediately  over  the  lava-source,  continued  to  rumble  and  to  discharge 
molten  matter  outside  their  cavities.  The  vapor  which  escaped  from  the 
seething  wall  of  lava  crowded  in  dark  contortions  round  the  orifice  of  the 
craters.  Some  of  it  was  red  or  yellow,  owing  to  the  reflection  of  the  red- 
hot  matter,  and  some  was  variously  shaded  by  the  trains  of  debris  ejected 
with  it ;  but  it  was  impossible  to  follow  them  with  the  eye,  so  rapid  was 
their  flight.  An  unintelligible  tumult  of  harsh  sounds  simultaneously 
burst  forth  ;  they  were  like  the  noises  of  saws,  whistles,  and  of  hammers 
falling  on  an  anvil.  Sometimes  one  might  have  fancied  it  like  the  roar- 
ing of  the  waves  breaking  upon  the  rocks  during  a  storm,  if  the  sudden 
dxplosiops  had  not  added  their  thunder  to  all  this  upi'oar  of  the  elements. 
One  felt  dismayed,  as  if  before  some  living  being,  at  the  sight  of  these 
groups  of  hillocks,  roaring  and  smoking,  and  increasing  in  size  every  hour, 
by  the  debris  which  they  vomited  forth  from  the  interior  of  the  earth. 
The  volcano,  however,  then  commenced  to  rest ;  the  erupted  matter  did 
not  rise  much  beyond  100  yards  above  the  craters,  while,  according  to  the 
statement  of  M.  Fouque,  at  the  commencement  of  the  eruption  it  had  been 
thrown  to  a  height  of  1850  to  1950  yards. 

During  the  six  first  days  the  quantity  of  lava  which  issued  from  the 
fissure  of  Monte  Frumento  was  estimated  at  117  cubic  yards  a  second, 
equivalent  to  a  volume  twice  the  bulk  of  the  Seine  at  low-water  time. 
In  the  vicinity  of  the  outlets  the  speed  of  the  current  was  not  less  than 
20  feet  a  minute ;  but  lower  down,  the  stream,  spreading  over  a  wider 
surface,  and  throwing  out  several  branches  into  the  side  valleys,  grad- 
ually lost  its  initial  speed,  and  the  fringes  of  scoriae,  which  were  pushed 
on  before  the  incandescent  matter,  advanced  on  the  average,  according  to 
the  slope  of  the  ground,  not  more  than  1^  to  6  feet  a  minute.*  On  the 
2d  of  February  the  principal  current,  the  breadth  of  which  varied  from 
300  to  550  yards,  with  an  average  thickness  of  49  feet,  reached  the  upper 
ledge  of  the  escarpment  of  Colla-Vecchia,  or  Colla-Grande,  three  miles 
from  the  fissure  of  eruption,  and  plunged  like  a  cataract  into  the  gorge 
below.  It  was  a  magnificent  spectacle,  especially  during  the  night,  to  see 
this  sheet  of  molten  matter,  dazzling  red  like  liquid  iron,  making  its  way, 

*  These  figures,  borrowed  from  the  account  of  the  Professor  Orazio  Silvestri,  are  the  re- 
sults of  measurements  made  by  Viotti,  the  engineer. 


ERUPTION  OF  ETNA  IN  1865.  423 

in  a  thin  layer,  from  the  heaps  of  brown  scoriae  which  had  gradually  ac- 
cumulated up  above ;  then,  carrying  with  it  the  more  solid  lumps,  which 
dashed  one  against  the  other  with  a  metallic  noise,  it  fell  over  into  the 
ravine,  only  to  rebound  in  stars  of  fire.  But  this  splendid  spectacle 
lasted  only  for  a  few  days ;  the  fiery  fall,  by  losing  in  height,  diminished 
gradually  in  beauty.  In  front  of  the  cataract,  and  under  the  jet  itself, 
there  was  formed  an  incessantly  increasing  slope  of  lava,  which  ultimately 
filled  up  the  ravine,  and,  indeed,  prolonged  the  slope  of  the  valley  above. 
From  the  reservoir,  which  was  more  than  160  feet  deep,  the  stream  con- 
tinued to  flow  to  the  east  toward  Mascali,  filling  up  to  the  brink  the 
winding  gorge  of  a  dried-up  rivulet. 

By  the  middle  of  the  month  of  February,  the  fiery  stream,  already  more 
than  six  miles  long,  made  but  very  slow  progress,  and  the  still  liquid  lava 
found  it  difficult  to  clear  an  outlet  through  the  crust  of  stones  cooled  by 
their  contact  with  the  atmosphere  ;  when,  all  of  a  sudden,  a  breaking  out 
took  place  at  the  side  of  the  stream,  at  a  point  some  distance  up,  not  far 
from  the  source.  Then  a  fresh  branch  of  the  burning  river,  flowing  to- 
ward the  plains  of  Linguagrossa,  swallowed  up  thousands  of  trees  which 
had  been  felled  by  the  woodman.  This  second  inundation  of  lava  did 
not,  however,  last  long.  The  villages  and  towns  situated  at  the  base  of 
the  mountain  were  no  longer  directly  menaced ;  but  the  disasters  caused 
by  the  eruption  were,  notwithstanding,  very  considerable.  A  number  of 
farm-houses  were  swept  away ;  vast  tracts  of  pasturage  and  cultivated 
ground  were  covered  by  slowly  hardening  rock,  and — a  misfortune  which 
was  all  the  worse  on  account  of  the  almost  general  deforesting  of  Sicily 
— a  wide  band  of  forest,  coniprising,  according  to  the  various  estimates 
that  were  made,  from  100,000  to  130,000  trees — oaks,  pines,  chestnuts,  or 
birches — was  conjpletely  destroyed.  When  seen  from  the  lower  part  of 
the  mountain,  all  these  burning  trunks  borne  along  upon  the  lava,  as  if 
upon  a  river  of  fire,  singularly  contributed  to  the  beauty  of  the  spectacle. 
As  is  always  the  case  in  the  events  of  this  world,  the  misfortune  of  some 
proved  to  be  a  source  of  gratification  to  others.  During  the  earliest  pe- 
riod of  the  eruption,  while  the  villagers  of  Etna  looked  at  it  with  stupor, 
and  were  bitterly  lamenting  over  the  destruction  of  their  forests,  hun- 
dreds of  curious  spectators,  brought  daily  by  the  steamboats  from  Cata- 
nia and  Messina,  came  to  enjoy  at  their  ease  the  contemplation  of  all  the 
splendid  horrors  of  the  conflagration. 

The  aspect  of  the  current  of  lava,  as  it  appeared  covered  with  its  en- 
velope of  scoriae,  was  scarcely  less  reraai'kable  than  the  sight  of  the  mat- 
ter in  motion.  The  black  or  reddish  aspect  of  the  cheire  was  all  rough- 
ened with  sharp-edged  projections,  which  resembled  steps,  pyramids,  or 
twisted  columns,  on  which  it  was  a  difficult  matter  to  venture,  except  at 
the  risk  of  tearing  the  feet  and  hands.  Some  months  after  the  commence- 
ment of  the  eruption,  the  onwai'd  motion  of  the  interior  of  the  molten 
stone,  which,  by  breaking  the  outer  crust  in  every  direction,  had  ulti- 
mately given  it  this  rugged  outline,  was  still  visibly  taking  place.     Here 


424  T^^  EARTH. 

and  there  cracks  in  the  rock  allowed  a  view,  as  if  through  an  air-hole,  of 
the  red  and  liquid  lava  swelling  up  as  it  flowed  gently  along  like  some 
viscous  matter.  A  metallic  clinking  sound  was  incessantly  heard,  pro- 
ceeding from  the  fall  of  the  scoriae,  which  were  breaking  under  the  press- 
ure of  the  liquid  matter.  Sometimes,  on  the  hardening  current  of  lava, 
a  kind  of  blister  gradually  rose,  which  either  opened  gently,  or  bursting 
with  a  crash  gave  vent  to  the  molten  mass  which  formed  it.  FumeroUes, 
composed  of  various  gases,  according  to  the  degree  of  heat  of  the  lava 
which  gave  rise  to  them,  jetted  out  from  all  the  issues.  Even  on  the 
banks  of  the  river  of  stone  the  soil  was  in  many  places  all  burning  and 
pierced  with  crevices,  through  which  escaped  a  hot  air  thoroughly  charged 
with  the  smell  of  burnt  roots. 

.  On  the  slopes  of  the  Frumento,  quite  cbse  to  the  upper  part  of  the  fis- 
sure, at  a  spot  where  the  liquid  mass  had  flowed  like  a  torrent,  M.  Fouque 
noticed  a  remarkable  phenomenon ;  sheaths  of  solidified  lava  were  sur- 
rounding the  trunks  of  pines,  and  thus  showing  the  height  to  which  the 
current  of  molten  stone  had  reached.  In  like  manner,  the  streams  of  ob- 
sidian which  flow  rapidly  from  the  basin  of  Kilauea,  in  the  isle  of  Hawaii, 
leave  behind  them  on  the  branches  of  the  trees  numerous  stalactites,  like 
the  icicles  which  are  formed  by  melting  snow  which  has  again  frozen. 
Below  the  escarpments  of  the  Frumento,  the  torrent,  which  was  there  re- 
tarded in  its  progress,  had  not  contented  itself  with  bathing  for  a  mo- 
ment the  trunks  of  the  forest  trees,  but  had  laid  them  low.  Great  trunks 
of  trees,  broken  down  by  the  lava,  lay  stretched  in  disorder  on  the  un- 
even bed  of  the  stream,  and,  although  they  were  only  separated  from  the 
molten  matter  by  a  crust  a  few  inches  thick,  numbers  of  them  were  still 
clothed  with  their  bark ;  several  had  even  j^reserved  their  branches.  At 
the  edge  of  the  cheire,  some  pine-trees,  which  had  perhaps  been  preserved 
from  the  fire  by  their  moisture  being  converted  by  the  heat  into  a  kind 
of  coating  of  steam,  were  surrounded  by  a  wall  of  heaped-up  lava,  and 
their  foliage  still  continued  green ;  it  could  not  yet  be  ascertained  if  the 
sources  of  the  sap  had  perished  in  their  roots. 

In  some  places,  rows  of  firs  very  close  together  were  suflficientto  change 
the  direction  of  the  flow,  and  to  cause  a  lateral  deviation.  Not  far  from 
the  crater  of  eruption,  on  the  western  bank  of  the  great  cheire,  a  trunk  of 
a  tree  was  noticed  which  by  itself  had  been  able  to  keep  back  a  branch 
of  the  stream,  and  to  prevent  it  from  filling  up  a  glen  which  opened  im- 
mediately below.  This  tree,  being  thrown  down  by  the  weight  of  the 
scoria?,  had  fallen  so  as  to  bar  up  a  slight  depression  in  the  ground  which 
presented  a  natural  bed  to  the  molten  matter.  The  latter  had  bent  and 
cracked  the  trunk,  but  had  failed  in  breaking  it,  and  the  stony  torrent 
had  remained  suspended,  so  to  speak,  above  the  beautiful  wooded  slopes 
which  it  threatened  to  destroy  completely. 

Round  the  very  mouth  of  the  volcano,  a  vast  glade  was  formed  in  the 
forest ;  the  ground  was  covered  every  where  with  ashes  which  the  wind 
had  blown  up  into  hillocks,  like  the  dunes  on  the  sea-coast ;  all  the  trees 


ERUPTIONS     OF      ETNA 


PL.X\. 


"Di-awTi  by    A  Vuillfinin     aft.'r  Sartonus  "JeWaheribausen. 

HARPER  &  BROTHERS.  HEW  YORK 


Eng'^ty  Erhard. 


ERUPTION  OF  ETNA  IN  1865.  425 

liad  been  broken  down  by  the  volcanic  projectiles,  and  burned  by  the 
scoriae  and  small  stones.  The  nearest  trees  that  were  met  with,  at  un- 
equal distances  from  the  mouths  of  eruption,  had  had  their  branches  torn 
off  by  the'  falling  lumps  of  stone,  or  were  buried  in  ashes  up  to  their  ter- 
minal crown.  A  spectator  might  have  walked  among  a  number  of  yel- 
low branches  which  were  once  the  tops  of  lofty  pines.  Thus,  on  the  pla- 
teau of  Frumento  and  the  lower  slopes,  every  thing  was  changed  both  in 
form  and  aspect ;  we  might  justly  say  that,  by  the  effects  of  the  erupted 
matter,  the  outline  of  the  sides  of  Etna  itself  had  been  perceptibly  modi- 
fied. 

And  yet  this  last  eruption,  one  of  the  most  important  in  our  epoch,  is 
but  an  insignificant  episode  in  the  history  of  the  mountain  ;  it  was  but  a 
mere  pulsation  of  Etna.  During  the  last  twenty  centuries  only,  more 
than  seventy-five  eruptions  have  taken  place,  and  in  some  of  them  the 
flows  of  lava  have  been  more  than  twelve  miles  in  length,  and  have  cov- 
ered areas  of  more  than  forty  square  miles,  which  were  once  in  a  perfect 
state  of  cultivation,  and  dotted  over  with  towns  and  villages.  In  former 
ages,  thousands  of  other  lava-flows  and  cones  of  ashes  have  gilidually 
raised  and  lengthened  the  slopes  of  the  mountain.  The  mass  of  Mount 
Etna,  the  total  bulk  of  which  is  three  or  four  thousand  times  greater  than 
the  most  considerable  of  the  rivers  of  stone  vomited  from  its  bosom,  is,  in 
fact,  from  its  summit  to  its  base,  down  even  to  the  lowest  submarine 
depths,  nothing  but  the  product  of  successive  eruptions  throwing  out  the 
molten  matter  of  the  interior.  The  volcano  itself  has  slowly  raised  the 
walls  of  its  crater,  and  then  extended  its  long  slopes  down  to  the  waters 
of  the  Ionian  Sea.  By  its  fresh  beds  of  lava  and  scoriae  incessantly  re- 
newed one  upon  the  other,  it  has  ultimately  reared  its  summit  into  the 
regions  of  snow,  and  has  become,  as  Pindar  called  it,  the  great  "  pillar  of 
heaven." 


426  ^^^^  EARTH. 


CHAPTER  LXII. 

SKA-COAST  LINE  OF  VOLCANOES. — THE  PACIFIC  "CIRCLE  OF  FIRE." — VOLCA- 
NOES OF  THE  INDIAN  OCEAN  ;  OF  THE  ATLANTIC ;  OF  THE  MEDITERRA- 
NEAN ;    OF  THE    CASPIAN ;   OF   CENTRAL   ASIA. 

The  earth  being  generally  looked  upon  as  immobility  itself,  it  is  a  very 
strange  thing  to  see  it  open  to  shoot  out  into  the  air  torrents  of  gas,  and 
shedding  forth  like  a  river  the  molten  rocks  of  its  interior.  From  what 
invisible  source  do  all  these  fluid  matters  proceed  which  spread  out  in 
sheets  over  vast  regions  ?  Whence  come  those  enormous  bodies  of  steam, 
extensive  enough  to  gather  immediately  in  clouds  round  the  loftiest  sum- 
mits, and  sometimes  indeed  to  fall  in  actual  rain-showers  ?  Science,  as  we 
have  already  said,  has  not  completely  answered  these  questions,  the  posi- 
tive solution  of  which  would  be  so  highly  important  for  our  knowledge 
of  the  globe  on  which  we  live. 

According  to  an  ancient  popular  belief,  Etna  merely  vomits  forth,  in  the 
shape  of  vapor,  the  water  which  the  sea  has  poured  into  the  gulf  of  Cha- 
rybdis.  This  legend,  although  clothed  in  a  poetic  garb,  has  in  fact  be- 
come the  hypothesis  which  is  thought  beyond  dispute  by  those  savants 
who  look  upon  volcanic  eruptions  as  being  a  series  of  phenomena  caused 
chiefly  by  water  converted  into  steam. 

The  remarkable  fact  that  all  volcanoes  are  arranged  in  a  kind  of  lino 
along  the  coasts  of  the  sea,  or  of  inland  lacustrine  basins,  is  one  of  the 
great  points  which  testify  in  favor  of  this  opinion  as  to  the  infiltration  of 
water,  and  give  to  it  a  high  degree  of  probability.  The  Pacific,  which  is 
the  principal  reservoir  of  tlie  water  of  our  earth,  is  circled  round  by  a  se- 
ries of  volcanic  mountains,  some  ranged  in  chains,  and  others  very  dis- 
tant from  one  another,  but  still  maintaining  an  evident  mutual  connec- 
tion,  constituting  a  "  circle  of  tire,"  the  total  development  of  which  is 
about  22,000  miles  in  length.  This  ring  of  volcanoes  does  not  exactly 
coincide  with  the  semicircle  formed  by  the  coasts  of  Australia,  the  Sunda 
Islands,  the  Asiatic  continent,  and  the  western  coasts  of  the  New  World, 
Like  a  crater  described  within  some  ancient  and  more  extensive  outlet 
of  eruption,  the  great  circle  of  igneous  mountains  extends  its  immense 
curve  in  a  westward  direction  across  the  waves  of  the  Pacific,  from  New 
Zealand  to  the  peninsula  of  Alaska ;  on  the  east,  it  is  based  on  the  coast 
of  America,  rising  in  the  south  so  as  to  form  some  of  the  loftiest  summits 
of  the  Andes. 

The  still  smoking  volcanoes  of  New  Zealand,  Tongariro  and  the  cone 
of  Whakari,  on  White  Island,  are,  in  the  midst  of  the  southern  waters  of 
the  Pacific  properly  so  called,  the  first  evidence  of  volcanic  activity.     On 


DISTRIBUTION  OF  VOLCANOES.  427 

the  north,  a  considerable  space  extends  in  which  no  volcanoes  have  yet 
been  observed.  The  group  of  the  Feejee  Islands,  at  which  the  volcanic 
ring  recommences,  presents  a  large  number  of  former  craters  which  still 
manifest  the  internal  action  of  the  lava  by  the  abundance  of  thermal 
springs.  At  this  point,  a  branch  crossing  the  South  Sea  in  an  oblique 
direction  from  the  basaltic  islands  of  Juan  Fernandez  as  far  as  the  active 
volcanoes  of  the  Friendly  group,  unites  itself  with  the  principal  chain 
which  passes  round,  in  a  northeast  direction,  the  coasts  of  Australia  and 
Xew  Guinea.  The  volcanoes  of  Abrim  and  Tanua,  in  the  New  Hebrides, 
Tinahoro,  in  the  archipelago  of  Santa  Cruz,  and  Semoya,  in  the  Salomon 
Isles,  succeeding  one  after  the  other,  connect  the  knot  of  the  Feejees  to 
the  region  of  the  Sunda  Islands,  where  the  earth  is  so  often  agitated  by 
violent  shocks.  This  region  may  be  considered  as  the  great  focus  of  the 
lava  streams  of  our  planet.  On  the  kind  of  broken  isthmus  which  con- 
nects Australia  with  the  Indo-Chinese  peninsula,  and  separates  the  Pacific 
Ocean  from  the  great  Indian  seas,  one  hundred  and  nine  volcanoes  are 
vomiting  out  lava,  ashes,  or  mud  in  full  activity,  destroying  from  time  to 
time  the  towns  and  the  villages  which  lie  upon  their  slopes ;  sometimes, 
in  their  more  terrible  explosions,  they  ultimately  explode  bodily,  covering 
with  the  dust  of  their  fragments  areas  of  several  thousands  of  miles  in  ex- 
tent. From  Papua  to  Sumatra,  every  large  island,  including  probably  the 
almost  unknown  tracts  of  Borneo,  is  pierced  with  one  or  more  volcanic 
outlets.  There  are  Timor,  Flores,  Sumbawa,  Lombok,  Bali,  and  Java, 
which  last  has  no  less  than  forty-five  volcanoes,  twenty-eight  of  which 
are  in  a  state  of  activity,  and,  lastly,  the  beautiful  island  of  Sumatra. 
Then,  to  the  east  of  Borneo — Ceram,  Amboyna,  Gilolo,  the  volcano  of 
Ternata,  sung  by  Camotins,  Celebes,  Mindanao,  Mindoro,  and  Luzon  ;  these 
Ibrm  across  the  sea,  as  it  were,  two  great  tracks  of  fire. 

Northward  of  Luzon,  thq  volcanic  ring  curves  gradually  so  as  to  fol- 
low a  direction  parallel  to  the  coast  of  Asia.  Formosa,  the  Liou-Kieou 
archipelago,  and  other  groups  of  islands  stand  in  a  line  over  the  subma- 
rine volcanic  fissure;  farther  on,  there  are  the  numerous  volcanoes  of 
Japan,  one  of  which,  Fusiyama,  with  a  cone  of  admirable  regularity,  is 
looked  upon  by  the  inhabitants  of  Niphon  as  a  sacred  mountain,  from 
which  the  gods  come  down.  The  elongated  archipelago  of  the  Kuriles, 
comprising  about  a  dozen  volcanic  orifices,  unites  Japan  to  the  peninsula 
of  Kamtschatka,  in  which  no  less  than  fourteen  volcanoes  are  reckoned  as 
being  in  full  activity.  To  the  east  of  this  peninsula,  the  range  of  craters 
suddenly  changes  its  direction,  and  describes  a  graceful  semicircle  across 
the  Pacific,  from  Behring  Island  to  the  point  of  Alaska.  Thirty-four 
smoking  cones  stand  on  this  great  transversal  dike,  extending  from  conti- 
nent to  continent.  Ounimak,  which  rises  on  the  extremity  of  the  penin- 
sula of  Alaska,  the  peak  of  which  is  7939  feet  in  height,  serves  as  the 
western  limit  of  the  New  World,  and  is  also  pierced  by  a  crater  in  a 
state  of  full  activity. 

Eastward  of  the  peninsula,  the  volcanic  chain  extends  along  the  sea- 


428 


THE  EAETII. 


coast  of  the  continent.  Mount  St.  Elias,  one  of  the  highest  summits  in 
America,  often  vomits  lava  from  its  crater,  which  opens  at  an  elevation 
of  17,716  feet.  Farther  to  the  south,  another  active  volcano,  Mount 
Fair  weather,  rises  to  a  height  of  14,370  feet.  Next  comes  Mount  Edge- 
cumbe,  in  Lazarus  Island,  and  the  volcanic  region  of  British  Columbia. 
The  whole  chain  of  the  Cascades,  in  Oregon,  as  well  as  the  parallel  ranges 
of  the  Sierra  Nevada  and  the  Rocky  Mountains,  are  overlooked  by  a  great 
number  of  volcanoes;  but  only  a  few  of  them  continue  to  throw  out 
smoke  and  ashes :  these  are  Mount  Baker,  Renier,  and  St.  Helens,  enor- 
mous peaks  10,000  to  16,000  feet  high.  In  California  and  Northern  Mex- 
co,  it  is  probable  that  the  basaltic  and  trachytic  mountains  on  the  coast 
no  longer  present  any  outlets  of  eruption.     Subterranean  activity  is  not 


Fig.  171.  Curve  of  Volcanic  Islands. 

manifested  with  any  degree  of  violence  until  .we  reach  the  high  plateaux 
of  Central  Mexico.  There  a  series  of  volcanoes,  rising  over  a  fissure 
crossing  the  continent,  extends  over  the  whole  plateau  of  Anahuac,  from 
the  Southern  Ocean  to  the  Gulf  of  Mexico.  The  Colima,  then  the  celebra- 
ted Jorullo,  which  made  its  appearance  in  1759,  the  Nevado  de  Tolima,  Is- 
tacihuetl,  Popocatepetl,  Orizaba,  and  Tuxtla  are  the  vents  for  the  furnace 
of  lava  which  is  boiling  beneath  the  Mexican  plateau.  To  the  south,  in 
Guatemala  and  the  South  American  republics,  thirty  burning  mountains, 
much  more  active  and  terrible  than  thqse  of  Anahuac,  rise  in  two  chains, 
wone  of  which  is  parallel  to  the  sea-coast,  and  the  other  crosses  obliquely 
the  isthmus  of  Nicaragua.  Among  these  numerous  volcanoes  there  are 
some,  the  names  of  which  have  become  famous  on  account  of  the  fright- 
ful disasters  which  have  been  caused  by  their  eruptions.  Such  are  the 
mountains  del  Fuego  and  del  Agua,  above  the  Ciudad- Antigua  of  Guate- 
mala ;  the  Phare  d'lsalco,  which  during  the  night  lights  up  far  and  wide 
the  plains  of  Salvador  with  its  jets  of  molten  stone  and  its  column  of 
red  smoke;  Coseguina,  the  last  great  eruption  of  which  was  probably 
the  most  formidable  of  modem  times ;  the  Viejo,  Nuevo,  Momotombo, 


VOLCANOES  -OF  AMERICA. 


429 


and  other  mountains,  which  are  almost  worshiped  from  being  so  much 
dreaded.* 

The  depressions  of  the  isthmuses  of  Panama  and  Darien  interrupt  the 
series  of  volcanoes  which  borders  the  coast  of  the  Pacific.  The  peak  of 
Toliraa,  which  rises  to  the  great  height  of  17,716  feet,  is  the  most  northern . 
of  the  active  volcanoes  of  South  America,  and  is  also  one  of  the  most  dis- 
tant from  the  sea  among  all  the  fire-vomiting  mountains,  for  the  distance 
from  its  base  to  the  Pacific  coast  is  not  less  than  124  miles.  South  of  Toli- 
ma,  and  the  great  plateau  of  Pasto,  where  there  likewise  exists  a  crater. 


Fig.  172.  Equatorial  Volcanoes. 

stands  the  magnificent  group  of  sixteen  volcanoes,  some  already  extinct 
and  some  still  smoking,  over  which  towers  the  proud  dome  of  Chimbo- 
razo.  Occupying  an  elliptical  space,  the  greater  axis  of  which  is  only 
about  112  miles  long,  this  group,  comprising  the  Tunguragua,  Carahui- 
zo,  Cotopaxi,  Antisana,  Pichincha,  Imbabura,  and  Sangay,  is  often  looked 
upon  as  but  one  volcano  with  several  cones  of  eruption ;  it  is  the  cluster 
which,  on  the  southern  coasts  of  the  Isthmus  of  Panama,  corresponds  sym- 

*  Moritz  Wagner. 


430  ^^^  EARTH. 

metrically  to  the  volcanic  group  of  Anahuac.  South  of  Sangay,  which  is 
perhaps  the  most  destructive  volcano  on  the  earth,  the  chain  of  the  Cor- 
dilleras offers  no  volcanoes  for  a  length  of  about  030  miles ;  but  in  South- 
ern Peru  the  volcanic  series  recommences,  an'd  outlets  of  eruption  still  in 
action  open  at  intervals  among  extinct  volcanoes  and  domes  of  trachyte. 
The  three  smoking  peaks  of  the  inhabited  part  of  Chili,  the  mountains  of 
Antuco,  Villarica,  and  Osorno,  terminate  the  series  of  the  great  American 
volcanoes;*  the  activity  of  subterranean  action  is,  however,  di^losed  by 
some  other  less  elevated  craters  down  to  the  extremity  of  the  continent 
as  far  as  the  point  of  Terra  del  Fuego.  This  is  not  all ;  the  South  Shet- 
land Islands,  situated  in  the  Southern  Ocean,  in  a  line  with  the  New 
World,  are  likewise  volcanic  in  their  character ;  and  if  the  same  direction 
be  followed  toward  the  polar  regions,  the  line  will  ultimately  touch  upon 
the  coasts  of  the  land  of  Victoria,  on  which  rise  the  two  lofty  volcanoes 
of  Erebus  and  Mount  Terror,  discovered  by  Sir  John  Ross.  Stretching 
round  the  sphere  of  the  earth,  the  great  volcanic  circle  is  extended  toward 
the  north  by  various  islets  of  the  antarctic,  and  ultimately  rejoins  the 
archipelago  of  New  Zealand.  Thus  is  completed  the  great  ring  of  fire 
which  circles  round  the  whole  surface  of  the  Pacific  Ocean. 

Within  this  immense  amphitheati-e  of  volcanoes  a  multitude  of  those 
charming  isles,  which  are  scattered  in  pleiads  over  the  ocean,  are  also  of 
volcanic  origin,  and  many  of  them  can  be  distinguished  from  afar  by  their 
smoking  or  flaming  ci'aters.  Of  this  kind  are  some  of  the  Marianne  and 
Gallapagos  Islands,  Avhich  contain  several  orifices  in  full  activity,  and 
more  than  two  thousand  cones  in  a  state  of  repose.  Among  these  we 
must  especially  mention  the  Sandwich  Islands,  the  lofty  volcanoes  of 
which  rise  in  the  middle  of  the  central'basin  of  the  North  Pacific  like  so 
many  cones  of  eruption  in  the  midst  of  a  former  crater  changed  into  a 
lake.  The  Mauna-Loa  and  Mauna-Kea,  the  two  great  volcanic  summits 
of  the  island  of  Hawaii,  are  each  more  than  13,000  feet  in  height;  and  the 
eruptions  of  the  first  cone,  which  are  still  in  full  activity,  must  be  reck- 
oned among  the  most  magnificent  spectacles  of  this  kind.  On  the  sides 
of  the  Mauna-Loa  opens  the  boiling  crater  of  Kilauea,  which  is,  without 
doubt,  the  most  remarkable  lava-source  which  exists  on  our  planet. 

Round  the  circumference  of  the  Indian  Ocean  the  border  of  volcanoes 
is  much  less  distinct  than  round  the  Pacific ;  still  it  is  possible  to  recog- 
nize some  of  its  elements.  To  the  north  of  Java  and  Sumatra,  the  volca- 
noes of  which  overlook  the  eastern  portion  of  the  basins  of  the  Indian 
seas,  stretches  the  volcanic  archipelago  of  the  Andaman  and  Nicobar  Isl- 
ands, in  which  there  are  several  cones  of  eruption  in  full  activity.  On 
the  west  of  Ilindostan,  the  peninsula  of  Kutch,  and  the  delta  of  the  Indus, 
are  often  agitated  by  subterranean  forces.  Many  mountains  on  the  Ara- 
bian coast  are  nothing  but  masses  of  lava ;  and,  if  various  travelers  are 
to  be  believed,  the  volcanic  furnace  of  these  countries  is  not  yet  extinct. 
The  Kenia,  the  great  mountain  of  Eastern  Africa,  has  on  its  own  summit 
*  Philippi,  Mittheilungen  von  Petermann,  vol.  iv.,  1861. 


VOLCANOES  OF  THE  ATLANTIC.  431 

a  crater  still  in  action — perhaps  the  only  one  which  exists  on  this  conti- 
nent. Lastly,  a  large  nnmber  of  islands  which  surround  the  Indian 
Ocean  on  the  west  and  on  the  south — Socotora,  Mauritius,  Reunion,  St. 
Paul,  and  Amsterdam  Island — are  nothing  but  cones  of  eruption,  which 
have  gradually  emerged  from  the  bed  of  the  ocean. 

The  volcanic  districts  which  are  scattered  on  the  edge  of  the  Atlantic 
are  likewise  distributed  with  a  kind  of  symmetry  round  three  sides  of 
this  great  basin.  On  the  north,  Jan  Mayen,  so  often  wrapt  in  mist,  and 
the  more  considerable  island  of  Iceland,  pierced  by  numerous  craters, 
Hecla,  the  Skapta-Jokul,  the  Kotlugaja,  and  seventeen  other  mountains 
of  eruption,  separate  the  Atlantic  from  the  Polar  Ocean.  At  about  1500 
miles  nearer  the  equator,  the  peaks  of  the  Azores,  some  extinct  and  some 
still  burning,  rise  out  of  the  sea.  The  archipelago  of  the  Canaries,  over 
which  towers  the  lofty  mass  of  the  peak  of  Teyda,  continues  toward  the 
south  the  volcanic  line  of  the  Azores,  and  is  itself  prolonged  by  the  smok- 
ing summits  of  the  Cape  de  Verde  Islands.  All  the  other  mountains  of 
lava  which  spring  up  from  the  bed  of  the  Atlantic  more  to  the  south  ap- 
pear to  have  completely  lost  their  activity,  and  on  the  coast  itself  there 
is,  according  to  Bui'ton,  only  one  volcano  still  in  action* — that  of  the 
Cameroons.  With  regard  to  the  "  line  of  fire"  along  the  western  Atlan- 
tic, it  is  developed  at  the  entrance  of  the  Caribbean  Sea  with  perfect  reg- 
ularity, like  the  range  of  the  Aleutian  Isles.  Trinidad,  Grenada,  St.  Vin- 
cent, St.  Lucia,  Dominica,  Guadaloupe,  Montserrat,  Nevis,  St.  Kitts,  and 
St.  Eustatius  are  so  many  outlets  ot  volcanic  force,  either  through  their 
smoking  craters  or  their  mud-volcanoes,  their  solfataras  or  their  thermal 
springs.  North  and  south  of  the  Antilles,' the  eastern  coast  of  America 
does  not  present  a  single  vent  of  eruption.  It  is  a  remarkable  fact  that 
the  two  volcanic  groups  of  the  Antilles  and  the  Sunda  Islands  are  situa- 
ted exactly  at  the  antipodes  one  of  the  other,  and  also  in  the  vicinity  of 
the  two  poles  of  flattening,  the  existence  of  which  on  the  surface  of  the 
globe  has  been  proved  by  the  recent  calculations  of  astronomers,*  More 
than  this,  these  two  great  volcanic  centres,  which  are  undoubtedly  the 
most  active  on  the  whole  earth,  flank,  one  on  the  west  and  the  other  on 
the  east,  the  immense  curve  of  volcanoes  which  spreads  round  the  Pacific. 

The  Mediterranean  is  not  surrounded  by  a  circle  of  volcanoes;  but 
there,  as  elsewhere,  it  is  from  the  midst  of  the  sea,  or  immediately  on  the 
sea-coast,  that  the  burning  mountains  rise  —  Etna,  Vesuvius,  Stromboli, 
Volcano,  Epomeo,  and  Santorin.  In  like  manner,  the  volcanoes  of  mud 
and  gas  of  the  peninsula  of  Apcheron,  and  the  summit  of  Demavend, 
14,436  feet  high,  rise  at  no  great  distance  from  the  Caspian  Sea.  With 
regard  to  the  volcanoes  of  Mongolia — the  Turfan,  which  is  said  to  be  still 
in  action,  and  the  Pe-chan,  which,  according  to  Chinese  authors,  vomited 
forth,  up  to  the  seventh  century,  "  fire,  smoke,  and  molten  stone,  which 
hardened  as  it  cooled  "f — their  existence  is  not  yet  absolutely  proved ; 
but  even  if  these  mountains,  situated  in  the   centre  of  the  continent, 

*  See  above,  p.  14.  f  Chroniques  Chinoises.     Unmholdt,  Tableaux  de  la  Nature. 


432  THE  EARTH. 

should  be  in  full  activity,  their  phenomena  might  depend  on  the  vicinity 
of  extensive  sheets  of  water,  for  this  very  region  of  Asia  still  possesses  a 
large  number  of  lakes,  the  remnants  of  a  former  inland  sea,  almost  as  vast 
as  the  Mediterranean, 

What  is  the  number  of  volcanoes  which  are  still  vomiting  forth  lava 
during  the  present  period  of  the  earth's  vitality  ?  It  is  difficult  to  ascer- 
tain, for  often  mountains  have  seemed  for  a  long  time  to  be  extinct ; 
forests  have  grown  up  in  their  disused  craters,  and  their  beds  of  lava 
have  been  covered  up  under  a  rich  carpet  of  vegetation,  when  suddenly 
the  sleeping  force  beneath  is  aroused  and  some  fresh  volcanic  outlet  is 
opened  through  the  ground.  When  Vesuvius  woke  up  from  its  protract- 
ed slumber  to  swallow  up  Pompeii  and  the  other  towns  lying  round  its 
base,  it  had  rested  for  some  centuries,  and  the  Romans  looked  upon  it  as 
nothing  but  a  lifeless  mountain  like  the  peaks  of  the  Apennines.  On  the 
other  hand,  it  is  very  possible  that  some  craters,  from  which  steam  and 
jets  of  gas  are  still  escaping,  or  which  have  thrown  out  lava  during  the 
historic  era,  have  entered  decisively  into  a  period  of  repose,  ceasing  some- 
how to  maintain  their  communication  with  the  subterranean  centre  of 
molten  matter.  The  number  of  vents  which  serve  for  the  eruption  of 
lava  can,  therefore,  be  ascertained  in  a  merely  approximate  way.  Hum- 
boldt enumerates  223  active  volcanoes;  Keith  Johnston  arrives  at  the 
larger  number  of  270,  190  of  which  are  comprehended  in  the  islands  and 
the  Pacific  "circle  of  fire;"  but  this  latter  estimate  Is  probably  too  small. 
To  the  number  of  these  burning  mountains,  standing  nearly  all  of  them 
on  the  sea-shore,  or  in  the  vicinity  of  some  great  fresh-water  basin,  must 
be  added  the  salses,  or  mud-volcanoes,  which  are  also  found  near  large 
sheets  of  salt  water.  With  regard  to  the  thousands  of  extinct  volcanoes 
which  rise  in  various  parts  of  the  interior  of  continents,  geology  shows 
that  the  sea  used  formerly  to  extend  round  their  bases. 


VOLi 


Volcano^*   ctre.    irvdioat^A 

tffrftdf  Acts.  *J^^ 


0  of    fan 20 


JSL. 


Ji^ 


Jjigd  ly  Ilrhard 


HARPEB.  &  EROT' 


NOES 


PL.XXI 


Di-awn  by  AVuilLur: 


S.  NEW  YORK 


EUVJLPE  OF  STEAM  FROM  CRATERS.  433 


CHAPTER  LXm. 

TORRENTS    OF   STEAM  ESCAPING  FROM  CRATERS. GASES   PRODUCED   BY  THE 

DECOMPOSITION    OF    SEA- WATER.  —  HYPOTHESES    AS    TO    THE    ORIGIN    OF 
ERUPTIONS. — INDEPENDENCE    OF   THE    SEVERAL   VOLCANIC    OUTLETS. 

One  of  the  most  decisive  arguments  which  can  be  used  in  favor  of  a 
free  communication  existing  between  marine  basins  and  volcanic  centres 
is  drawn  from  the  large  quantities  of  steam  which  escape  from  craters 
during  an  eruption,  and  compose,  according  to  M.  Ch.  Sainte-Claire  De- 
ville,  at  least  999  thousandths  of  the  supposed  volcanic  smoke.  During 
the  eruption  of  Etna,  in  1865,  M.  Fouquo  attempted  to  gauge  approxi- 
mately the  volume  of  water  which  made  its  escape  in  a  gaseous  form 
from  the  craters  of  eruption.  By  taking  as  his  scale  of  comparison  the 
cone  which  appeared  to  him  to  emit  an  average  quantity  of  steam,  he 
found  this  mass,  reduced  to  a  liquid  state,  would  be  equivalent  to  about 
79  cubic  yards  of  water  for  each  general  explosion.  Now,  as  these  ex- 
plosions took  place  on  the  average  every  four  minutes  during  a  hundred 
days,  he  arrived  at  the  result,  that  the  discharge  of  water  during  the  con- 
tinuance of  the  phenomenon  might  be  estimated  at  2,829,600  cubic  yards 
of  water — a  flow  equal  to  that  of  a  permanent  stream  discharging  55  gal- 
Ions  a  second.  Added  to  this,  account  ought  to  have  been  taken  of  the 
enormous  convolutions  of  vapor  which  were  constantly  issuing  from  the 
great  terminal  crater  of  Etna,  and,  bending  over  under  the  pressure  of 
the  wind,  spread  out  in  an  immense  ftrch  around  the  vault  of  the  sky.  In 
great  volcanic  eruptions  it  often  happens  that  these  clouds  of  steam,  be- 
coming suddenly  condensed  in  the  higher  layers  of  the  atmosphere,  fall 
in  heavy  showers  of  rain,  and  form  temporary  torrents  on  the  mountain- 
sides. According  to  the  statements  of  Sir  James  Ross,  the  mountain  Ere- 
bus, of  the  antarctic  land,  is  covered  with  snow,  which  it  has  just  vomited 
forth  in  the  form  of  vapor.  It  has  besides  been  remarked  that  the  vapor 
which  issues  from  volcanoes  is  not  always  warm ;  often,  according  to  Poep- 
pig,  it  is  of  the  same  temperature  as  the  surrounding  air. 

As  was  said  long  since  by  Krug  von  Xidda,  a  German  savant^  volca- 
noes must  be  looked  upon  as  enormous  intermittent  springs.  The  ba- 
saltic flows  may  be  compared  to  streams  on  account  of  the  water  which 
they  contain.  It  is  probable  that  most  of  the  lava  which  flows  from  vol- 
canic fissures  owes  its  mobility  to  the  innumerable  particles  of  vapor 
which  fill  up  all  the  interetices  of  the  moving  mass.  Being  composed  in 
great  measure  of  crystals  already  formed,  as  may  be  proved  by  an  ex- 
amination of  the  cheires,  in  the  body  of  which  may  be  noticed  nodules 
and  crystals  rounded  by  friction,  the  lava  would  be  unable  to  descend 

£e 


434  THE  EARTH. 

over  the  slopes  if  it  were  not  rendered  fluid  by  its  mixture  with  steam  ; 
and  the  gradual  slackening  in  speed  and  ultimate  stoppage  of  the  flow 
are  chiefly  caused  by  the  setting  free  of  the  gases  which  served  as  a  vehi- 
cle to  the  solid  matter.  Owing  to  this  rapid  loss  of  their  humidity,  ba- 
salts contain  in  their  pores  but  a  very  slight  quantity  of  water  in  com- 
parison with  other  rocks.*  Yet  even  old  lavas  themselves  contain  as 
much  as  10  to  19  thousandths  of  water  at  the  edges  of  the  bed,  and  5  to 
18  thousandths  at  the  centre.f 

The  various  substances  which  are  produced  from  craters  also  tend  to 
show  that  sea-water  has  been  decomposed  in  the  great  laboratory  of  lava. 
Ordinary  salt  or  chloride  of  sodium,  which  is  the  mineral  that  is  most 
abundant  in  sea-water,  is  also  that  which  is  deposited  the  first  and  most 
plentifully  round  the  orifices  of  eruption.  Sometimes,  the  scoriae  and  ashes 
are  covered  for  a  vast  space  with  a  white  efilorescence,  which  is  nothing 
but  common  salt ;  one  might  fancy  it  a  shingly  beach  which  had  just 
been  left  by  the  ebbing  tide.  After  each  eruption  of  Hecla,  the  Iceland- 
ers are  in  the  habit,  it  is  said,  of  collecting  salt  on  the  slopes.  The  lava 
from  the  eruption  of  Frumento,  analyzed  by  M.  Fouque,  contained  about 
13  ten  thousandths  of  marine  salt. 

Almost  all  the  other  component  parts  of  sea-water  are  likewise  found 
in  the  gases  and  deposits  oi  fumerolles ;  only  the  salts  of  magnesia  have 
disappeared,  but  still  are  found  under  another  form  among  the  volcanic 
products.  Being  decomposed  by  the  high  temperature,  just  as  they 
would  be  in  the  laboratoiy  of  a  chemist,  they  go  to  constitute  other 
bodies.  Thus  the  chloride  of  magnesium  is  changed  into  hydrochloric 
acid  and  magnesia ;  the  gas  escapes  in  abundance  from  the  fumeroUes, 
while  the  magnesia  remains  fixed  in  the  lava.J 

As  M.  Ch.  Sainte-Claire  Deville  was  the  first  to  ascertain  with  certain- 
ty, four  successive  periods  may  be  t^bserved  in  every  eruption,  each 'of 
which  periods  assumes  a  distinct  character,  owing  to  the  exhalation  of 
certain  substances.  After  the  first  period,  remarkable  especially  for  ma- 
rine salt  and  the  various  compounds  of  soda  and  potash,  comes  a  second 
in  which  the  temperature  is  lower,  and  during  which  brilliantly  colored 
deposits  of  chloride  of  iron  are  formed  and  hydrochloric  and  sulphurous 
acids  are  expelled.  When  the  temperature  is  below  392°  (Fahr.),  there 
are  ammoniacal  salts  and  needles  of  sulphur,  which  are  found  in  yellowish 
masses  on  the  scoriae  of  lava.  Lastly,  when  the  heat  of  the  erupted 
bodies  is  below  212°  (Fahr.),  the  fumeroUes  eject  nothing  but  steam,  azote, 
carbonic  acid,  and  combustible  gases.  Thus  the  activity  of  the  exhala- 
tions and  deposits  is  in  proportion  to  the  incandescence  of  the  lava.  At 
the  commencement  of  the  eruption,  the  orifices  throw  out  a  large  quan- 
tity of  substances,  from  marine  salt  to  carbonic  acid ;  but  by  degrees  the 
power  of  elaboi'ation  weakens  simultaneously  with  the  heat,  and  the  gases 

*  Poulett  Scrope,  Volcanoes. 

t  Delesse,  Bulletin  de  la  Societe  Geologique  de  France,  1859. 

X  Fouqud,  Phenomenes  Chimiques  de  VEruption  de  VEtna  en  1865. 


EXHALATIONS  OF  VOLCANOES.  435 

ejected  gradually  diminish  in  number,  and  testify,  by  their  increasing; 
rarity,  to  the  approaching  cessation  of  volcanic  phenomena.  In  conse- 
quence of  the  difference  which  is  presented  by  the  exhalations  during  the 
various  phases  of  eruptions  of  lava,  observers  have,  at  first  sight,  thought 
that  each  volcano  was  distinguished  by  emanations  peculiar  to  itself 
Hydrochloric  acid  was  looked  upon  as  one  of  the  normal  products  of 
Vesuvius,  and  sulphurous  vapors  as  more  especial  to  Etna.  It  was  stated 
(with  Boussingault)  that  carbonic  acid  was  exhaled  specially  by  the  vol- 
canoes of  the  Andes ;  and,  with  Bunsen,  it  was  believed  that  combustible 
gases  prevailed  in  the  eruptions  of  Hecla.* 

In  his  beautiful  investigations  into  the  various  chemical  phenomena 
presented  by  Etna  and  the  neighboring  volcanic  outlets,  such  as  Vesuvius 
and  Stromboli,  M,  Fouque  appears  to  have  established  as  a  fact  which 
must  be  henceforth  beyond  dispute,  that  the  gradual  series  of  these 
emanations  is  just  that  which  would  be  produced  by  the  decomposition 
of  sea-water.  Added  to  this,  we  also  find  in  lava  iodine  and  fluorine, 
both  of  which  we  should  expect  to  detect  in  it  on  account  of  their  pres- 
ence in  sea- water.  The  salts  of  bromine,  of  which,  however,  only  a  slight 
trace  is  found  in  sea-water,  have  not  yet  been  detected  in  volcanic  prod- 
ucts, which,  no  doubt,  proceeds  from  the  difiiculty  which  chemists  have 
experienced  in  separating  such  very  small  quantities. 

The  other  matters  ejected  by  eruptions  are  of  terrestrial  origin,  and 
evidently  proceed  from  rocks  reduced  by  heat  to  a  liquid  or  pasty  state ; 
they  consist  principally  of  silica  and  alumina,  and  contain  besides  lime, 
magnesia,  potash,  and  soda.  Oxides  of  ii'on  also  enter  into  the  composi- 
tion of  lava,  to  the  extent  of  more  than  one  tenth,  which  is  a  very  consid- 
erable proportion,  and  warrants  us  in  looking  upon  the  volcanic  flows  as 
actual  torrents  of  iron-ore ;  sometimes,  indeed,  this  metal  appears  in  a 
pure  «tate.  It  is  to  this  presence  of  iron  that  lava  especially  owes  its 
reddish  color,  and  the  sides  of  the  crater  their  diversely  colored  sides. 
Compounds  of  copper,  manganese,  cobalt,  and  lead  are  also  met  with  in 
lava ;  but,  in  comparison  with  the  iron,  they  are  but  of  slight  importance. 
Lastly,  phosphates,  ammonia,  and  gases  composed  of  hydrogen  and  car- 
bon, are  discharged  during  eruptions.  The  presence  of  these  bodies  is 
explained  by  the  enormous  proportion  of  animal  and  vegetable  matter 
which  is  decomposed  in  sea-water.  Ehrenberg  found  the  remains  of  ma- 
rine animalcula  in  the  substances  thrown  out  by  volcanoes. 

Is  the  composition  of  the  lava,  and  especially  that  of  the  vapor  and 
gases,  the  same  in  those  eruptions  which  take  place  at  a  great  distance 
from  the  ocean  ?  It  is  probable  that,  as  regards  this  point,  considerable 
differences  might  be  established  between  the  products  ef  volcanoes  placed 
on  the  sea-coast,  such  as  Vesuvius  and  Etna,  and  those  which  rise  far  in 
the  interior  of  the  land,  as  Tolima,  JoruUo,  and  Purace,  This  compara- 
tive study,  however,  which  would  be  calculated  to  throw  light  on  the 
chemical  phenomena  of  deep-lying  beds,  has  as  yet  been  made  at  only  a 
•  Fonqn6,  Revue  det  Denx  Mondes,  Angnst,  1866. 


436  "^HE  EARTH. 

few  points.  Eruptions  are  rare  in  volcanoes  situated  far  from  the  coast, 
and  when  they  do  take  place,  scientific  men  do  not  happen  to  be  on  the 
spot  to  study  the  course  of  the  occurrence.  Popocatepetl,  one  of  the 
most  remarkable  continental  volcanoes,  produces  a  large  quantity  of  hy- 
drochloric acid;  the  snow  from  it,  which  has  a  very  decided  muriatic 
taste,  is  carried  by  the  rain  into  the  Lake  of  Tezcuco,  where,  in  conjunc- 
tion with  soda,  it  forms  salt.* 

When  the  water,  either  of  sea  or  rivers,  penetrates  into  the  crevices  of 
the  terrestrial  envelope,  it  gradually  increases  in  temperature  the  same  as 
the  rocks  it  passes  through.  It  is  well  known  that  this  increase  of  heat 
may  be  estimated  on  the  average,  at  least  as  regards  the  external  part  of 
the  planet,  at  l°(Fahr,)  for  every  54  feet  in  depth.  Following  this  law, 
water  descending  to  a  point  7500  feet  below  the  surface  would  show,  in 
the  southern  latitudes  of  Europe,  a  temperature  of  about  212°  (Fahr.), 
But  it  would  not  on  this  account  be  converted  into  steam,  but  would 
remain  in  a  liquid  state,  owing  to  the  enormous  pressure  which  it  has  to 
undergo  from  the  upper  layers.  According  to  calculations,  which  are 
based,  it  is  true,  on  various  hypothetical  data,  it  would  be  at  a  point  more 
than  nine  miles  below  the  surface  of  the  ground  that  the  expansive  force 
of  the  water  would  attain  sufficient  energy  to  balance  the  weight  of  the 
superincumbent  liquid  masses,  and  to  be  suddenly  converted  into  steam  at 
a  temperature  of  800°  to  900°  (Fahr.).  These  gaseous  masses  would  then 
have  force  to  lift  a  column  of  water  of  the  weight  of  1500  atmospheres; 
if,  however,  from  any  cause,  they  can  not  escape  as  quickly  as  they  are 
formed,  they  exercise  their  pressure  in  every  direction,  and  ultimately  find 
their  way  from  fissure  to  fissure  until  they  reach  the  fused  rocks  which 
exist  in  the  depths.  To  this  incessantly  increasing  pressure  we  must, 
therefore,  attribute  the  ascent  of  the  lava  into  vent-holes  of  volcanoes,  the 
occurrence  of  earthquakes,  the  fusion  and  the  rupture  of  the  terrestrial 
crust,  and,  finally,  the  violent  eruptions  of  the  imprisoned  fluids.f  But 
why  should  the  vapor  thus  pervade  the  subterranean  strata  and  upheave 
them  into  volcanic  cones,  when,  by  the  natural  effect  of  its  overcoming  the 
columns  of  water  which  press  it  down,  it  ought  simply  to  rise  toward  the 
bed  of  the  sea  from  which  it  descended  ?  In  the  present  state  of  science, 
this  is  a  question  to  which  it  seems  absolutely  impossible  to  give  a  satis- 
factory answer,J  and  geologists  must  at  least  have  the  merit  of  candidly 
acknowledging  their  ignorance  on  this  point.  The  discoveries  of  natural 
philosophy  and  chemistry,  which  have  been  the  means  of  making  known 
to  us  the  enormous  activity  of  steam  in  volcanic  eruptions,  will  doubtless, 
sooner  or  later,  explain  to  us  in  what  way  this  activity  is  exercised  in  the 
subterranean  cavities.  But  at  the  present  time  the  phenomena  which  are 
taking  place  in  the  interior  of  our  globe  are  not  better  known  to  us  than 
the  history  of  the  lunar  volcanoes. 

•  Virlet,  Bulletin  de  la  Societe  Geologique  de  France,  May  1st,  1865. 
t  Buff,  Briefe  uher  die  Physik  der  Erde. 
%  Otto  Volger,  Erdbeben  der  Schweiz. 


CONNECTION  OF  VOLCANOES. 


437 


Be  this  as  it  may,  the  direct  observations  which  have  been  made  on 
volcanic  eruptions  have  now  rendered  it  a  very  doubtful  point  whether 
the  lavas  of  various  volcanoes  proceed  from  one  and  the  same  reservoir 
of  molten  matter,  or  from  the  supposed  great  central  furnace  which  is 
said  to  fill  the  whole  of  the  interior  of  the  planet.  Volcanoes  which  are 
very  close  to  one  another  show  no  coincidence  in  the  times  of  their  erup- 
tions, and  vomit  forth,  at  different  epochs,  lavas  which  are  most  dissimilar 
both  in  appearance  and  miueralogical  composition.     These  facts  would  be 


Fig.  173.  Line  of  Fracture  between  Etna  and  Vesuvias. 


eminently  impossible,  if  the  craters  were  fed  from  the  same  source.  Etna, 
the  group  of  the  Lipari  Isles,  and  Ve^vius,  have  often  been  quoted  as  be- 
ing volcanic  outlets  placed  upon  the  same  fracture  of  the  terrestrial  crust ; 
and  it  is  added,  in  corroboration  of  this  assertion,  that  a  line  traced  from 
the  Sicilian  volcano  to  that  of  Naples  passes  through  the  ever-active  fur- 
nace of  the  Lipari  Isles.  Although  the  mountain  of  Stromboli,  so  regular 
in  its  eruptions,  is  situated  on  a  line  slightly  divergent  from  the  principal 
line,  and,  on  the  other  side,  the  volcanic  isles  of  Salini,  Alicudi,  and  Feli- 
cudi  tend  from  east  to  west,  it  is  possible,  and  even  probable,  that  Vesu- 


438  ^^'  EARTH. 

vius  and  Etna  are  in  fact  situated  on  fissures  of  the  earth  which  Avere  once 
in  mutual  communication.  But  during  the  thousands  of  years  in  which 
these  great  craters  have  been  at  work,  no  connection  between  their  erup- 
tions has  ever  been  positively  certified. 

Sometimes,  as  in  1865,  Vesuvius  vomits  forth  lava  at  the  same  time  as 
Etna ;  sometimes  it  is  in  a  state  of  repose  when  its  mighty  neighbor  is 
in  full  eruption,  and  rouses  up  when  the  lava  of  Etna  has  cooled.  There 
is  nothing  which  afibrds  the  slightest  indication  of  any  law  of  rhythm  or 
periodicity  in  the  eruptive  phenomena  of  the  two  volcanoes.  The  inhab- 
itants of  Stromboli  state  that,  during  the  winter  of  1865,  at  the  moment 
when  the  sides  of  Etna  were  rent,  the  volcanic  impulse  manifested  itself 
very  strongly  in  their  island  by  stirring  up  the  always  agitated  waves 
of  the  lava-crater  which  commands  their  vineyards  and  houses.  A  com- 
parative calm,  however,  soon  succeeded  this  temporary  efiervescence,  and 
in  the  adjacent  island  of  Volcano  no  increase  of  activity  was  noticed.  If 
the  shafts  of  Etna,  Vesuvius,  and  the  intervening  volcanoes,  take  their 
rise  in  one  and  the  same  ocean  of  liquid  lava,  all  the  lower  craters  must 
necessarily  overflow  simultaneously  with  the  most  elevated.  Now,  as 
has  often  been  noticed,  the  lava  may  ascend  to  the  summit  of  Etna,  at  a 
height  of  10,827  feet,  without  a  simultaneous  flow  of  rivers  of  molten 


??iWi«-" 


Fig.  174  Section  of  the  Island  of  Hawaii. 


stone  from  Vesuvius,  Stromboli,  and  Volcano,  which  are  respectively  but 
one  third,  one  fourth,  and  one  tenth  the  height  of  the  former.  In  like 
manner,  Kilauea,  situated  on  the  sides  of  Mauna-Loa,  in  the  Isle  of  Hawaii, 
in  no  way  participates  in  the  eruptions  of  the  central  crater  opening  at  a 
point  9800  feet  higher  up,  and  not  more  than  12  miles  away.  If  there  is 
any  present  geological  connection  between  the  volcanoes  of  one  and  the 
same  region,  it  probably  must  be  attributed  to  the  fact  of  their  phenome- 
na depending  on  the  same  climatic  causes,  and  not  because  their  bases 
penetrate  to  one  and  the  same  ocean  of  fire.  Volcanic  orifices  are  not, 
therefore, "  safety-valves,"  for  two  centres  of  activity  may  exist  on  one 
mountain  without  their  eruptions  exhibiting  the  least  appearance  of  con- 
nection.* 

Isolated  as  they  are  amid  all  the  other  formations  on  the  surface  of  the 
earth,  lavas  appear  as  if  almost  i^ependent  of  the  rest.  Basalts,  tra- 
chytes, and  volcanic  ashes,  are  the  comparatively  modern  products  which 
are  scarcely  met  with  in  the  periods  anterior  to  the  Tertiary  age.  Only 
a  very  small  quantity  of  these  lavas  of  eruption  has  been  found  in  the 
Secondary  and  Palaeozoic  rocks.  Formerly,  most  geologists  thought  that 
the  granites  and  rocks  similar  to  them  had  issued  from  the  earth  in  a 
I)asty  or  liquid  state ;  they  looked  upon  them  as  the  "  lavas  of  the  past," 
*  Dana,  Proceedings  of  the  American  Association,  1849. 


ORIGIN  OF  VOLCAXOEa.  439 

and  believed  that  these  first  eruptive  rocks  were  succeeded  in  age  after 
age  by  the  diorites,  the  porphyries,  the  trap-rocks,  then  by  the  trachytes 
and  the  basalts  of  our  own  day,  all  drawn  from  a  constantly  increasing 
depth.  They  thought  also  that,  in  the  future,  when  the  whole  series  of 
the  present  lavas  shall  have  been  thrown  up  to  the  surface,  volcanoes 
would  produce  other  substances  as  distinct  from  the  lavas  as  the  latter 
are  from  the  granite.  Granites,  however,  differ  so  much  from  the  tra- 
chytes and  basalts  as  to  render  it  impossible  for  us  to  imagine  that  they 
have  the  same  origin ;  added  to  which,  the  labors  of  modern  savmits  have 
proved  that,  under  the  action  of  fire,  granite,  and  the  other  rocky  masses 
of  the  same  kind,  would  have  been  unable  to  assume  the  crystalline  tex- 
ture which  distinguishes  them.  We  are,  then,  still  ignorant  how  volcanic 
eruptions  commenced  "upon  the  earth,  and  how  they  are  connected  with 
the  other  great  phenomena  which  have  co-operated  in  the  formation  of 
the  external  strata  of  the  srlobe. 


440  ^^^  EARTH. 


CHAPTER  LXIV. 

GROWTH  OP  VOLCANOES. THEORIES  OF  HUMBOLDT  AND  LEOPOLD  VON 

BUCH  AS  TO  THE  UPHEAVAL  OF  CRATERS. DISAGREEMENT  OF  THESE 

THEORIES  WITH  THE  FACTS  OBSERVED. 

Considered  singly,  each  volcano  is  nothing  but  a  mere  orifice,  tempo- 
rary or  permanent,  through  which  a  furnace  of  lava  is  brought  into  com- 
munication with  the  surface  of  the  globe.  The  matter  thrown  out  accu- 
mulates outside  the  opening,  and  gradually  forms  a  cone  of  debris  more 
or  less  regular  in  its  shape,  which  ultimately  attains  to  considerable  di- 
mensions. One  flow  of  molten  matter  follows  another,  and  thus  is  grad- 
ually formed  the  skeleton  of  the  mountain  ;  the  ashes  and  stones  thrown 
out  by  the  crater  accumulate  in  long  slopes ;  the  volcano  simultaneously 
grows  wider  and  higher.  After  a  long  succession  of  eruptions,  it  at  last 
mounts  up  into  the  clouds,  and  then  into  the  region  of  permanent  snow. 
At  the  first  outbreak  of  the  volcano  the  orifice  is  on  the  surfjice  of  the 
ground ;  it  is  then  prolonged  like  an  immense  chimney  through  the  cen- 
tre of  the  cone,  and  each  new  river  of  lava  which  flows  from  the  summit 
increases  the  height  of  this  conduit.  Thus  the  highest  outlet  of  Etna 
opens  at  an  elevation  of  10,892  feet  above  the  level  of  the  sea ;  Tenerifie 
rises  to  12,139  feet;  Mauna-Loa,  in  Hawaii,  to  13,943  feet;  and,  more 
gigantic  still,  Sangay  and  Sahama,  in  the  Cordilleras,  attain  to  18,372  and 
23,950  feet  in  elevation. 

This  theory  of  the  formation  of  volcanic  mountains  by  the  accumula- 
tion of  lava  and  other  matters  cast  out  of  the  bosom  of  the  earth  presents 
itself  quite  naturally  to  one's  mind.  'Most  savants^  from  Saussure  and 
Spallanzani  down  to  Virlet,  Constant  Provost,  Poulett  Scrope,  and  Lyell, 
have  been  led,  by  their  investigations,  to  adopt  it  entirely ;  indeed,  in 
the  present  day  it  is  scarcely  disputed.  It  is  true  that  Humboldt,  Leo* 
pold  von  Buch,  and,  following  them,  M.  Elie  de  Beaumont,  have  put  forth 
quite  a  different  hypothesis  as  to  the  origin  of  several  volcanoes,  such  as 
Etna,  Vesuvius,  and  the  Peak  of  Teneriife.  According  to  their  theory, 
volcanic  mountains  do  not  owe  their  present  conformation  to  the  long- 
continued  accumulation  of  lava  and  ashes,  but  rather  to  the  sudden  up- 
heaval of  the  terrestrial  strata.  During  some  revolution  of  the  globe,  the 
pent-up  matter  in  the  interior  suddenly  upheaves  a  portion  of  the  crust 
of  the  planet  into  the  form  of  a  cone,  and  opens  a  funnel-shaped  gulf  be- 
tween the  dislocated  strata,  thus  by  one  single  pai'oxysm  producing  lofty 
mountains,  as  we  now  see  them.  As  an  important  instance  of  a  crater 
thus  formed  by  the  upheaval  and  rupture  of  the  terrestrial  strata,  Leo- 
pold von  Buch  mentions  the  enormous  abyss  of  the  Isle  of  Palma,  known 


FORMATION  OF  CRATERS. 


441 


by  the  natives  under  the  name  of  "  Caldron,"  or  Caldera.  This  funnel- 
shaped  cavity  is  of  enormous  dimensions,  and  is  not  less  than  four. or  five 
miles  in  width  on  the  average ;  the  bottom  of  it  is  situated  about  2000 
feet  above  the  level  of  the  sea.  Lofty  slopes,  from  1000  to  2000  feet  in 
height,  rise  round  the  vast  amphitheatre,  and  abut  upon  inaccessible  clifis, 


Fi-'.  175.  Isle  of  Palma. 


the  upper  ledges  of  which  reach  a  total  altitude  of  5900  to  6900  feet  in 
height.  The  highest  point,  the  Pico-de-los-Muchachos,  is  covered  by  snow 
during  the  winter  months  ;  and  although  it  penetrates  into  regions  of  the 
atmosphere  which  are  of  a  very  different  characteu  from  those  of  the  rest 
of  the  island,  the  slope  that  is  turned  toward  the  crater  is  |0  steep  that 


442  ^^^  EARTH. 

blocks  of  stone  falling  from  the   summit  roll  down  into  the  inclosed 
hollow. 

The  prodigious  cavity  in  the  Isle  of  Palma  was,  perhaps,  the  most  strik- 
ing instance  that  Leopold  von  Buch  could  bring  forward  in  favor  of  his 
hypothesis ;  nevertheless,  the  exploration  of  this  island,  since  carried  out 
by  Hartung,  Lyell,  and  other  travelers,  is  very  far  from  confirming  the 
ideas  of  the  illustrious  German  geologist.  The  lofty  side-walls  of  the 
hollow  appear  to  be  formed  principally,  not  of  solid  lava,  which  consti- 
tutes scarcely  a  quarter  of  the  whole  mass,  but  of  layers  of  ashes  and 
scoriae,  regularly  ai-ranged  like  beds  of  sand  on  the  incline  of  a  talus.* 
Basalts  and  strata  of  ashes  lie  upon  one  another  in  the  greatest  order  round 
the  inclosed  hollow,  which  would  be  a  fact  impossible  to  comprehend  if 
any  sudden  upheaval,  acting  in  an  upward  direction  with  sufficient  vio- 
lence to  break  the  terrestrial  crust,  had  shattered  and  ruptured  all  the 
strata,  and,  by  a  mighty  explosion,*opened  out  the  immense  Caldron  of 
Palma.  Finally,  if  a  phenomenon  of  this  kind  had  taken  place,  star- 
formed  cracks,  like  those  produced  in  broken  glass,  would  be  visible  across 
thie  thickness  of  the  upheaved  strata,  and  their  greatest  width  would  be 
turned  toward  the  crater.  Now  there  are  no  fissures  of  this  kind,  and 
the  ravines  in  the  circumference  of  the  volcano,  which  one  might  perhaps 
be  tempted  to  confound  with  actual  ruptures  of  the  ground,  become 
wider  in  proportion  as  they  approach  the  sea.  The  enormous  cavity  in 
Palma  is,  therefore,  a  crater  similar  to  those  of  volcanoes  of  less  dimen- 
sions. It  is,  however,  certain  that  the  Caldera  was  once  both  shallower 
and  less  in  extent,  for  the  ashes  and  volcanic  scoriae  are  easily  carried 
away  by  the  rain,  which  is  swallowed  up  in  the  bottom  of  the  basin,  and 
has  hollowed  out  for  itself  a  wide  drainasre-channel  in  a  southwest  direction. 


^■"^^'^^ 


Fig.  ITG.  Section  of  the  Island  of  Palm^  from  Southeast  to  Northwest. 


M.  Elie  de  Beaumont,  as  his  chief  support  of  Leopold  von  Buch's  hy- 
pothesis, brought  forward  the  fact  that  most  of  the  strata  of  lava — a  sec- 
tion of  which  may  be  seen  on  the  sides  of  Etna,  in  the  immense  amphi- 
theatre of  the  Val  del  Bove — are  very  sharply  inclined.  The  celebrated 
geologist  affirmed  that  thick  sheets  of  molten  matter  could  not  run  down 
steep  slopes  without  being  very  soon  reduced,  in  consequence  of  the  ac- 
celeration of  their  speed,  into  thin  layers  of  irregular  scoriae.  If  this  were 
really  the  case,  the  position  of  the  thick  flows  of  lava  in  the  Val  del  Bove 
must  have  changed  since  the  date  of  the  eruption ;  it  would  then  be 
necessary  to  admit  that  they  have  been  violently  tilted  up  after  having 
been  originally  deposited  on  the  soil  in  sheets,  which  were  either  horizon- 


VOLCANO  OF  JORULLA. 


443 


tal  or  very  gently  sloped.  Nevertheless,  the  recent  observations  made  by 
Sir  C.  Lyell,  those  of  Darwin  on  the  cones  of  the  Gallapagos  Isles,  and  of 
Dana  on  the  lava  flows  of  Kilauea ;  lastly,  the  remarks  of  the  Italian  sa- 
vants who  studied  on  the  spot  the  volcanic  phenomena  of  Vesuvius  and 
Etna,  have  satisfactorily  proved  that,  in  modern  times,  a  great  number  of 
rivers  of  lava,  and  especially  that  of  the  Val  del  Bove,  in  1852  and  1853, 
have  flowed  over  steep  slopes  varying  in  inclinations  from  15  to  40  de- 
grees. It  must,  besides,  be  undei-stood  that  the  lava  which  poured  over 
the  steepest  slopes  was  exactly  that  portion  which,  not  having  expei'i- 
enced  any  cause  of  delay,  or  met  with  any  obstacle,  in  its  course,  presented 
layers  of  the  most  uniform  consistence  and  the  most  regular  action. 


Fig.  177.  Volcano  of  Jornlla,  Mexico. 

One  of  the  strongest  arguments  of  scientific  men  in  favor  of  the  theory 
of  upheaval  is,  that  cei'tain  volcanic  mountains,  especially  that  of  Monte- 
Nuovo,  of  Pouzzoles,  and  JoruUo,  in  Mexico,  had  been  suddenly  raised  up 
by  the  swellings  of  the  soil.  Now  the  unanimous  testimony  of  those 
who,  more  than  three  centuries  ago,  witnessed  the  eruption  of  Monte- 
Nuovo  is,  that  the  earth  was  cleft  open,  affording  an  outlet  to  vapor, 
ashes,  scoriae,  and  lava,  and  that  the  hill,  very  much  lower  than  some  of 
the  subordinate  cones  of  Etna,  gradually  rose  during  four  days  by  the 
heaping  up  of  the  matter  thrown  out.     The  total  volume  of  this  eruption 


^4  THE  EABTH. 

was  no  doubt  considerable,  but  compared  with  the  amount  of  matter 
which  flowed  down  upon  Catania  in  1669,  or  with  the  rivers  of  lava  from 
Skaptar-Jokul,  it  is  a  mass  of  no  great  importance.  Added  to  this,  if  the 
soil  was  really  upheaved,  how  was  it  that  the  neighboring  houses  were 
not  thrown  down,  and  that  the  colonnade  of  the  Temple  of  Neptune, 
*  which  stands  at  the  foot  of  the  mountain,  kept  its  upright  position  ? 
With  regard  to  Jorullo,  which  rises  to  a  height  ^of  more  than  1650  feet, 
the  only  witnesses  of  this  volcano  making  its  first  appearance  were  the 
Indians,  who  fled  away  to  the  neighboring  heights,  distracted  with  terror. 
We  have,  therefore,  no  authentic  testimony  on  which  we  can  base  an  hy- 
pothesis as  to  any  swelling  up  of  the  ground  in  the  form  of  a  blister. 
Quite  the  contrary,  the  travelers  who  have  visited  this  Mexican  volcano 
since  Humboldt  have  discovered  beds  of  lava  lying  one  over  the  other,  as 
in  all  other  cones  of  eruption ;  and  more  than  this,  they  have  also  ascer- 
tained that  none  of  the  strata  in  the  ground  overlooked  by  the  mountain 
have  been  at  all  tilted  up.* 

It  is  true  enough  that  local  swellings  have  often  been  observed  in  the 
burning  matter  issuing  from  the  interior  of  the  earth  ;  in  many  places  the 
lava  is  pierced  by  deep  caverns,  and  entire  mountains — especially  that 
of  Volcano — have  so  many  hollows  in  the  rocks  on  their  sides  that  every 
step  of  the  climber  resounds  on  them  as  if  on  a  vault.  Besides,  the  lava 
itself,  being  a  kind  of  impure  glass,  is  so  pervaded  by  bubbles  filled  with 
volatile  matter  that,  when  acted  upon  by  fire,  so  as  to  expel  the  water  and 
the  gas,  it  loses  on  an  average,  according  to  Fouque,  two  thirds  of  its 
weight.  But  these  caverns,  these  hollows  arid  bubbles,  proceed  from  the 
mixture  of  the  lava  with  vapor  which  is  liberated  with  difliculty  from  the 
viscous  mass,  or  are  caused  by  the  longitudinal  rupture  of  the  strata  dur- 
ing an  eruption,  and  can  in  no  way  be  compared  to  the  immense  blister- 
like elevation  which  would  be  formed  by  the  strata  of  a  whole  district 
being  tilted  up  to  a  height  of  hundreds,  or  even  thousands,  of  yards,  leav- 
ing at  the  summit,  between  two  lines  of  fracture,  room  for  an  immense 
cavity. 

None  of  these  prodigious  upheavals  have  been  directly  observed  by 
geologists,  and  none  of  the  legends  invented  by  the  feai's  of  our  ancestors, 
referring  to  the  sudden  appearance  of  volcanic  mountains,  have  been  since 
confirmed.  Lastly,  the  very  structure  of  the  peaks  which  are  said  to 
have  risen  abruptly  from  the  midst  of  the  plains  testifies  to  the  gradual 
accumulation  of  material  that  has  issued  from  the  bowels  of  the  earth. 
It  is,  therefore,  prudent  to  dismiss  definitively  an  hypothesis  which  marks 
an  important  period  in  the  history  of  geology,  but  which,  for  the  future, 
can  only  serve  to  retard  the  progress  of  science. 

*  Arnold  Boscowitz,  Les  Volcans  et  les  Tremblements  de  Terre. 


JMR±NOEMENT  OF  VOLCANIC  OUTLETS. 


445 


CHAPTER  LXV. 

NUMBER   AND   AREANGEMENT    OF   VOLCANIC    OUTLETS. 
CANIC   CONES    AND   CBATEBS. 


-FORM    OF    VOL- 


As,  when  the  burning  matter  seeks  an  outlet,  the  earth  is  generally  cleft 
open  in  a  straight  line,  the  volcanic  orifices  are .  frequently  distributed 
somewhat  regularly  along  a  fissure,  and  the  heaps  of  erupted  matter  fol- 
low one  another  like  the  peaks  in  a  mountain  chain.    In  other  places,  how- 


Fj^.  176.  bones  of  Craters,  Hawaii. 

ever,  the  volcanic  cones  rise  without  any  apparent  order  on  ground  that 
is  variously  cleft,  just  as  if  a  wide  surface  had  been  softened  in  every  di- 
rection, and  had  thus  allowed  the  molten  matter  to  make  its  escape,  some- 
times at  one  point,  sometimes  at  another.  From  the  town  of  Naples — 
which  is  itself  built  on  half  a  crater  in  great  part  obliterated — to  the 
Isle  of  Nisida,  which  is  an  old  volcano  of  regular  form,  the  Phlegrajan 
Fields  present  a  remarkable  example  of  this  confusion  of  craters.  Some 
are  perfectly  rounded,  others  are  broken  into,  and  their  circle  is  invaded^ 
by  the  waters  of  the  sea :  grouped,  for  the  most  part,  in  irregular  clumps, 
even  encroaching  upon  one  another  and  blending  their  walls,  they  give  to 
the  whole  landscape  a  chaotic  appearance.  As  Mr.  Poulett  Scrope  very 
justly  remarks,  the  aspect  of  the  terrestrial  surface  at  this  spot  reminds 


44r( 


THE  EARTH. 


one  exactly  of  the  volcanic  districts  of  the  moon,  dotted  over,  as  it  is,  with 
•  craters. 

As  the  type  of  a  region  pierced  all  over  with  volcanic  orifices,  we  may 
also  mention  the  Isthmus  of  Auckland,  in  New  Zealand,  where  Dr.  Hoch- 


Fig.  179.  Auckland  and  its  Volcanoes. 


stetter  has  reckoned,  in  an  area  of  230  square  miles,  sixty-one  independ- 
ent volcanoes,  520  to  650  feet  in  height  on  the  average.  Some  are  mere 
cones  of  tufa;  others  are  heaps  of  scoriae,  or  even  eruptive  hillocks,  which 
have  shed  out  round  them  long  flows  of  lava.  At  one  time  the  Maori 
chiefs  used  to  intrench  themselves  in  these  craters  as  if  in  citadels ;  they 
escarped  the  outer  slopes  in  terraces,  and  furnished  them  with  palisades. 
At  the  present  day,  the  English  colonists,  having  become  lords  of  the  soil, 
have  constructed  their  farms  and  country  houses  on  these  ancient  volca- 
noes, and  are  constantly  bringing  the  soil  under  cultivation.* 
The  Safa,in  the  Djebel-Hauran,  is  also  a  complete  chaos  of  hillocks  and 
•  *  Ferd,  von  Hochstetter,  Neu-Seeland. 


DISPOSITION  OF  CRATERS. 


447 


abysses.  On  this  plateau  of  460  square  miles,  which  the  Arabs  call  a 
"  portion  of  hell,"  almost  all  the  craters  open  on  the  surface  of  the  ground, 
and  not  on  the  summits  of  volcanoes  scattered  here  and  there  on  the  black 


f^' 


^ 


Fig.180.  Cone  of  Tuff. 


Fig.  181.  Cone  of  Tuff,  and  Crater  of  Scorise. 


surface.  In  every  direction  there  may  be  seen  rounded  cavities  like  tJie 
vacuities  formed  in  scoriae  by  bubbles  of  gas,  only  these  cavities  are  600 
to  900  feet  wide,  and  65  to  160  feet  deep.  Some  are  isolated ;  some  either 
touch  or  are  separated  by  nothing  but  narrow  walls  like  masses  of  red  or 
darkish-colored  glass.  One  hardly  cares  to  venture  on  these  narrow  isth- 
muses, bordered  by  precipices,  and  intersected  here  and  there  by  fissures.* 
The  normal  form  of  the  volcanoes  in  which  the  work  of  eruption  takes 
place  is  that  ora  slope  oi debris  arranged  in  a  circular  form  round  the  out- 
let. Whether  the  volcano  be  a  mere  cone  of  ashes  or  mud  only  a  few 
yards  high,  or  rise  into  the  regions  of  the  clouds,  vomiting  streams  of  lava 


a.  Declivities  of  Toff.       6.  Cone  of  Lava.       c  Pyramid  of  Scorite. 


Fig.  IS'i.  Phiii  and  Section  of  the  Volcano  of  Rangitoto. 
•  Wetestein,  Zeitschn/t  fSr  Erdkunde,  1859. 


448 


THE  EARTH. 


over  an  extent  of  10  or  20  miles,  it  none  the  less  adheres  to  the  regular 
Ibrm  so  long  as  the  eruptive  action  is  maintained  in  the  same  channel,  and 
the  debris  thrown  out  falls  equally  on  the  external  slopes. 

The  beauty  of  the  cone  is  increased  by  that  of  the  crater.  The  term- 
inal orifice  from  which  the  lava  boils  out  well  deserves,  from  the  purity 
of  its  outline,  its  Greek  name  of  "cup,"  and  the  harmony  of  its  curve  con- 
trasts most  gracefully  with  the  declivity  of  the  slope.  In  some  volcanoes 
the  symmetry  of  the  architectural  lines  is  so  complete  that  the  crater  it- 
self contains  a  cone  placed  exactly  in  the  centre  of  the  cavity,  and  pierced 
by  a  second  crater  in  miniature,  from  which  vapor  makes  its  escape. 

Volcanoes  in  which  the  eruptive  action  frequently  changes  its  position 
— and  these  are  the  more  numerous  class — do  not  possess  this  elegance  of 
outline.  Very  often  the  upheaved  lava  finds  some  weak  place  in  the  walls 
of  the  crater ;  it  hollows  them  out  at  first,  and  then,  bringing  all  its  weight 
to  bear  on  the  rocks  Avhich  oppose  its  passage,  it  ultimately  completely 
breaks  down  the  edge  of  the  crater,  leaving  perhaps  only  one  side  stand- 
ing.    Among  the  European  volcanoes,  Vesuvius  is  the  best  example  of 


Ruinjordef 


Fijr.  1S3.  Mouut  Vesavius. 


these  ruptured  craters:  before  A.D  79,  the  escarpments  of  La  Somma, 
which  now  surround  with  their  semicircular  rampart  the  terminal  cone 


FORM  OF  VOLCANOES. 


449 


of  Vesuvius,  were  the  real  crater.  The  portion  of  it  which  no  longer  ex- 
ists disappeared,  and  buried  under  its  debris  the  towns  of  Herculaneum 
and  PonjpeiL 


Fig.  184.  Section  of  Vesuvius  from  South  to  North. 

Active  volcanoes,  however,  never  cease  to  increase  in  all  their  dimen- 
sions, and  sooner  or  later  the  breach  is  ultimately  repaired ;  the  remains 
of  the  former  craters  are  gradually  hidden  under  the  growing  slopes  of 
the  central  cone.  Thus  a  former  crater  on  Etna,  which  was  situated  at  a 
point  three  miles  in  a  straight  line  from  the  present  outlet,  at  the  com- 
mencement of  the  Val  del  Bove,  has  been  gradually  obliterated  by  the  lava 
of  successive  eruptions:  prolonged  explorations  on  the  part  of  MM.  Seyell 
and  Waltershausen  have  been  necessary  in  order  to  find  it  out.  The  nor- 
mal form  of  Etna  is  that  of  a  cone  of  debris  placed  upon  a  large  dome  with 
long  slopes,  becoming  more  and  more  gentle,  and  descending  gracefully 
toward  the  sea.  In  fact,  in  most  of  the  eruptions,  the  lava  does  not  rise  as 
far  as  the  great  crater,  and  breaks  thi'ough  the  sides  of  the  volcano  so  as  to 
flow  laterally  over  the  flanks  of  Etna.     These  eruptions,  succeeding  one 


Fig.  l^'S.  Section  ofEtua  from  West  to  East. 

another  in  the  course  of  centuries,  bring  about  the  necessaiy  result  of  grad- 
ually enlarging  the  dome  which  constitutes  the  mass  of  the  mountain,  thus 
breaking  the  uniformity  of  the  lateral  talus.  The  same  thing  occurs  with 
regard  to  Vesuvius  on  the  side,  which  faces  the  sea-coast.  There,  too,  the 
terminal  cone  stands  on  a  kind  of  dome,  which  has  been  gradually  formed 
by  the  coats  of  lava  running  one  over  the  other.  If  Vesuvius  continues  to 
be  the  great  volcanic  outlet  of  Italy,  and  rises  gradually  into  the  sky  by 


Fig.  ISd.  Mount  Orizaba. 

Ff 


450 


THE  EAETH. 


the  superposition  of  lava  and  ashes,  it  can  not  fail,  some  time  or  other,  to 
assume  a  form  similar  to  that  of  the  Sicilian  giant. 

The  volcanoes  which  present  cones  of  almost  perfect  regulai'ity  are  those 
which  have  their  terna^A  outlet  alone  in  a  state  of  activity,  and  vomit  out 
a  large  quantity  of  aSPI  or  other  matter  which  glides  readily  over  the 
slopes.  Among  this  class  of  mountains,  those  which  attain  any  consider- 
able elevation  are  distinguished  by  their  majesty  from  all  other  peaks. 
Stromboli,  although  it  is  not  more  than  2600  feet  in  height,  is  one  of  the 
wonders  of  the  Mediterranean.  From  its  proud  form,  it  will  readily  be 
understood  that  its  roots  plunge  down  into  the  sea  to  an  enormous  depth ; 


'»y/^''^ 


Fig.  187.  Profile  of  Orizaba. 

the  slope  of  dkbris  may  be  seen,  so  to  speak,  prolonged  under  the  water 
down  to  the  abysses  of  3000  to  4000  feet,  which  the  sounding-line  has  reach- 
ed at  the  bottom  of  the  ^olian  Sea.  At  sight  of  it  one  feels  as  if  suspend- 
ed in  the  mrast  of  the  void,  as  if  the  ship  was  sailing  in  the  air  midway  up 
the  mountain.     This  feeling  of  admiration  mingled  with  dread  increases 


FOMM  OF  VOLCANOES. 


451 


when  this  great  pharos  of  the  Mediterranean  is  approached  during  the 
night  over  the  dark-waved  sea.  Then  the  sky  above  the  summit  seems  all 
lighted  up  by  the  reflection  of  the  lava,  and  a  misty  band  of  clouds  and  va- 
por may  be  dimly  seen  girdling  round  the  body  of  the  volcano.  In  the 
daytime  the  impression  made  is  of  a  different  character;  but  it  is  none 
the  less  deep,  for  the  real  grandeur  of  Stromboli  consists  not  so  much  in 
the  immensity  of  the  mass  as  in  the  harmony  of  its  proportions. 

Volcanic  mountains  of  an  ideal  form  are  those  which  infant  nations  have 
most  adored.  Among  these  sacred  mountains  are  the  sublime  Cotopaxi 
of  the  Andes,  Orizaba  of  Mexico,  Mauna-Loa  of  Hawaii,  and  Fusi-Yama  of 
Japan.    The  volcanoes  of  Java,  and  chiefly  those  in  the  eastern  portion  of 


Fig.  188.  Volcanoes  of  Java. 


the  island,  also  present  a  very  majestic  appearance  on  account  of  their  iso- 
lation. Those  on  the  western  side  are  based  upon  an  undulating  plateau, 
which  causes  them  to  lose  their  appearance  of  height ;  but  on  the  east  all 
the  volcanic  mountains  rise  up  from  verdant  plains  like  islands  above  the 
waves  of  the  sea,  and  command  the  horizon  far  and  wide  with  their  enor- 
mous cones.  Between  the  Merapi  and  Lavoe  mountains  lies  a  depression, 
the  highest  ledge  of  which  exceeds  the  level  of  the  sea  by  only  312  feet. 
Between  Lavoe  and  Villis  the  plain  is  230  feet  in  height.  Lastly,  the 
plains  which  separate  the  Villis  and  Kelceet  mountains  nowhere  attain  an 
elevation  of  more  than  200  feet  above  the  ocean.* 

In  the  external  details  of  their  conformation  many  of  the  volcanoes  of 
Java  present  a  regularity  of  outline  which  is  all  the  more  striking,  since 
they  owe  it  in  great  part  to  the  monsoon  rains,  the  most  destructive 
agents  of  the  tropical  regions.  In  beating  against  the  mountains,  the 
clouds  let  fall  their  burden  of  moisture  on  the  slopes  composed  of  ashes 
and  loose  scoriae.  The  latter  ofier  but  a  slight  resistance  to  the  action  of 
the  temporary  torrents  which  carry  them  away,  and,  crumbling  down 
into  the  plains  which  surround  the  base  of  the  volcano,  are  deposited  in 
long  slopes,  like  those  caused  by  avalanches.  In  consequence  of  the  fall 
of  all  this  debris,  the  sides  of  the  mountain  are  cut  out  at  intervals  by  ra- 
♦  Junghuhn,  Java,  seine  Gestalt  und  innere  Bauart. 


452  ^^^  EARTH. 

vines  or  furrows,  which  gradually  widen  from  the  summit  to  the  base  of 
the  mountains,  and  attain  a  depth  of  200,  600,  and  660  feet.  There  are 
some  volcanoes,  such  as  the  Sumbing,  in  which  these  ravines  assume  so 
perfect  a  regularity  that  the  whole  mountain,  with  its  equidistant  furrows 
and  its  intermediate  walls,  resembles  a  gigantic  edifice  based  upon  enor- 
mous buttresses,  like  the  nave  of  a  Gothic  cathedral.* 

Formerly  the  beauty  of  the  island  and  the  fury  of  its  volcanoes  were 
the  cause  of  its  being  altogether  dedicated  to  Siva,  the  god  of  destruction ; 
and  in  the  very  craters  of  the  burning  mountains  the  worshipers  of  Terror 
and  Death  were  in  the  habit  of  building  their  temples.  In  many  spots  the 
ruins  of  these  sanctuai'ies  are  discovered  in  the  midst  of  trees  and  thickets, 
which  the  Arab  conquerors  have  left  to  grow  in  the  formidable  cavities 
of  the  volcanoes.  Semerce,  the  loftiest  j^eak  in  the  island,  Avas  the  sacred 
mountain  par  excellence  /  the  Sumbing,  which  rises  in  the  centre  of  the 
island,  was  the  "  nail  which  fastens  Java  to  the  earth."  Even  in  our  own 
time  some  faithful  followers  of  Siva  inhabit  a  sandy  plain,  more  than  four 
miles  wide,  which  was  once  the  crater  of  the  Tengger  volcano ;  every  year 
they  proceed  solemnly  to  pour  rice  on  the  summit  of  an  eruptive  cone, 
into  the  roaring  mouth  of  the  monster.  In  like  manner,  in  New  Zealand, 
the  ever-smoking  orifice  of  Tongariro  was  considered  as  the  only  place 
worthy  of  receiving  the  dead  bodies  of  their  great  chiefs :  when  cast  into 
the  crater,  the  heroes  went  to  sleep  among  the  gods. 

But  the  volcanic  divinities,  like  most  of  the  other  rulers  invoked  by  na- 
tions, did  not  content  themselves  with  the  fruits  of  the  earth  or  the  com- 
panionship of  a  few  warriors;  they  also  demanded  blood, both  by  their 
subterranean  roarings,  by  their  thundering  eruptions,  and  their  devasta- 
ting rivers  of  lava.  Innumerable  sacrifices  have  been  offered  to  volcanoes 
to  appease  their  anger :  impelled  by  a  mingled  feeling  of  fear  and  ferocity, 
the  priests  of  not  a  few  religions  have  cast  victims  with  great  pomp  into 
the  gaping  hollows  of  these  immense  furnaces.  Scarcely  three  centuries 
ago,  when  the  disciples  of  Christianity  were  exterminated  over  the  whole 
length  and  breadth  of  Japan,  the  followers  of  the  new  religion  were  thrown 
by  hundreds  into  one  of  the  craters  of  the  Unsen,  one  of  the  most  beauti- 
ful volcanoes  of  the  archipelago ;  but  this  offering  to  the  offended  gods 
did  not  appease  their  anger,  for,  toward  the  end  of  the  eighteenth  century, 
this  very  same  mountain  and  the  neighboring  summits  caused  by  their 
eruptions  one  of  the  most  frightful  disasters  of  any  that  are  mentioned  in 
the  history  of  volcanoes.  Actuated  by  a  feeling  of  dread  very  similar  to 
that  exhibited  by  the  Japanese  priests,  the  Christian  missionaries  in  Amer- 
ica recognized  in  the  burning  mountains  of  the  New  World  not  the  work 
of  a  god,  but  that  of  the  devil,  and  went  in  procession  to  the  edge  of  the 
craters  to  exorcise  them.  A  legend  tells  how  the  monks  of  Nicaragua 
climbed  the  terrible  volcano  of  Momotombo  in  order  to  quiet  it  by  their 
conjurations;  but  they  never  returned:  the  monster  swallowed  them  up. 
*  Arnold  Boscomtz,  Volcans  et  Tremblements  de  Terre. 


COMPOSITION  OF  LA  VA8.  453 


CHAPTER  LXVI. 
COMPOSITION  OP  lavas;  trachytes;  pumice-stone;  obsidian;  basalts; 

BASALTIC  COLONNADES. 

Lava  is  the  most  important  product  of  the  volcanic  fires.  The  various 
kinds  of  lava  differ  very  much  in  their  external  appearance,  in  the  color 
of  their  substance,  and  in  the  variety  of  their  crystals,  but  they  are  all 
composed  of  silicates  of  alumnia  or  magnesia,  combined  with  protoxide 
of  iron,  potash  or  soda,  and  lime.  When  the  feldspathic  minerals  pre- 
dominate, the  rock  is  generally  of  a  whitish,  grayish,  or  yellowish  hue, 
and  receives  the  name  of  trachyte.  When  the  lava  contains  an  abun- 
dance of  crystals  of  augite,  hornblende,  or  titaniferous  iron,  it  is  heavier, 
of  a  darker  color,  and  often  more  compact ;  it  then  takes  the  generic  for- 
mation of  basalt.  Numerous  varieties,  diversely  designated  by  geologists, 
belong  to  this  group. 

Of  all  the  lavas,  trachyte  is  the  least  fluid  in  its  form.  In  many  places 
rocks  .of  this  nature  have  issued  from  the  earth  in  a  pasty  state,  and  have 
accumulated* above  the  orifice  in  the  shape  of  a  dome,  "just  like  a  mass 
of  melted  wax."*  In  this  way  were  formed  the  great  domes  of  Auvergne, 
the  Puys  de  Dome  and  de  Sarcouy.  In  this  district  the  flows  of  trachytic 
lava  are  far  inferior  in  length  to  the  basaltic  cheires ;  the  most  important 
do  not  exceed  four  or  five  miles  in  length.  At  the  present-day,  eruptions 
of  trachyte  are  much  more  rare  than  those  of  other  lavas ;  so  much  so, 
that  certain  authore  class  all  the  trachytic  rocks  among  the  formations  of 
anterior  ages.  It  is,  however,  ascertained  that  most  of  the  American  vol- 
canoes and  those  of  the  Sunda  Archipelago  vomit  out  lava  of  this  nature; 
the  last  eruptions  of  the  ^olian  Isles,  Lipari  and  Volcano,  likewise  pro- 
duced only  trachyte  and  pumice-stone. 

Tliis  latter  substance  resembles  certain  white,  yellow,  or  greenish  sco- 
riae, which  issue  like  a  frothy  dross  from  the  furnaces  of  our  iron-works, 
and  is,  like  the  compact  trachyte,  of  a  feldspathic  nature.  Some  moun- 
tains are  almost  entirely  composed  of  it ;  among  others,  the  Monte  Bianco 
of  Lipari,  which,  viewed  from  a  distance,  appears  as  if  covered  with  snow. 
Long  white  flows,  like  avalanches,  fill  up  all  its  ravines,  from  the  summit 
of  the  mountain  to  the  shore  of  the  Mediterranean ;  the  slightest  move- 
ment caused  by  the  tread  of  an  animal  or  a  gust  of  wind  detaches  from 
the  surface  of  the  slope  hundreds  of  stones,  which  bound  down  to  tlie  foot 
of  the  incline,  and  are  borne  away  by  the  waves  which  bathe  the  base  of 
the  mountain.  In  the  southern  part  of  the  Tyrrhenean  Sea,  and  especially 
in  the  vicinity  of  the  Lipari  (iEolian)  Islands,  the  water  is  sometimes  cov- 
*  Poulett  Scrope,  Volcanoes:  the  Character  of  their  Phenomena,  etc. 


454 


THE  EARTH. 


ered  with  these  floating  stones,  almost  like  flakes  of  foam.  In  the  Cordil- 
leras the  currents  of  fresh  water  convey  the  morsels  of  pumice  to  consid- 
erable distances.  The  River  Amazon  drifts  down  large  quantities  of 
pumice  as  far  as  its  mouth,  more  than  3000  miles  from  the  place  where  it 
fell  into  the  river.  Bates  says  that  the  Indians,  who  live  too  far  away 
from  the  volcanoes  even  to  know  of  their  existence,  assert  that  these 
stones,  floating  down  the  river  by  the  side  of  their  canoes,  are  assuredly 
solidified  foam. 

The  external  appearance  of  various  lavas  difiers  even  more  than  their 
chemical  composition.  The  more  or  less  perfect  state  of  fluidity,  and  the 
presence  in  them  of  a  greater  or  less  quantity  of  bubbles  of  vapor,  give  a 
very  difierent  texture  to  rocks  which  are  composed  of  the  same  elements. 
Pumice-stone  has  the  appearance  of  sponge;  obsidian  looks  like  black 
glass,  and  sometimes  even  it  is  semi-transparent.  It  is  entirely  liquid, 
and  issues  from  the  interior  of  the  earth  like  a  stream  flowing  rapidly 
over  the  steeper  slopes,  and  coagulating  slowly  in  large  sheets  in  the  low 
ground  and  on  the  gentle  inclines  whither  its  own  weight  has  drawn  it. 
The  surface  of  obsidian — for  instance,  thai  of  Teneriffe — shines  with  a  vit- 
reous glitter ;  the  cleavage  of  the  rock  is  clean  and  sharp. 

Some  less  degree  of  fluidity  in  the  current  of  lava  gives  it  sometimes 
the  appearance  of  resin ;  this  is  the  stone  which  is  called  pechstein  (pitch- 
stone).  When  the  rock,  issuing  in  a  state  effusion  from  the  bosom  of  the 
mountain,  becomes  still  cooler,  it  contains  innumerable  pei*iBCtly-formed 
crystals,  and  only  owes  its  fluidity  to  the  particles  of  vapor  in  its  pores. 
The  external  layer  of  the  lava  is  also  immediately  covered  with  scoriae 
which  float  in  flakes  on  the  fiery  stream.  These  scoriae,  too,  assume  a 
great  variety  ©f  shapes ;  some  are  mammillated,  others  are  exceedingly 
rough  and  irregular.  In  the  Djebel-Haurau,  near  the  crater  of  Abu-Ga- 
nim,  there  is  an  infinity  of  needles  of  red  lava,  about  a  yard  high  on  the 
average,  and  bent  in  various  directions  toward  the  surface  of  the  plateau ; 
one  might  often  fancy  them  flames  half  beaten  down  under  the  pressure 
of  the  wind.  According  to  M.Wetzstein,  these  strange  stone  needles  pro- 
ceed from  an  eruption  of  flaky  lava.  In  the  Sandwich  Islands,  and  in  the 
Island  of  Reunion,  certain  crystals  of  a  ferruginous  appearance  are  group- 
ed at  the  outlet  of  the  crater  in  herbaceous  forms  of  the  most  curious  and 
sometimes  elegant  character.  Some  of  the  products  of  the  volcano  of 
Mauna-Loa  and  Kilauea  resemble  the  tow  of  hemp !  These  are  the  whit- 
ish filaments  which  are  sometimes  carried  away  by  the  wind ;  the  Kanakes 
used  to  consider  them  as  the  hair  of  Pele,  the  goddess  of  fire. 

Among  the  old  basaltic  lavas  there  are  some  to  which  the  name  of 
basalt  is  more  specially  applied,  which  present  a  columnar  disposition  with 
wonderful  regularity.  These  form  the  enormous  monuments,  much  more 
imposing  than  those  of  man,  which  seem  as  if  they  had  been  constructed 
by  giant  builders,  turning  their  mighty  hands  to  the  noble  art  of  archi- 
tecture, which  is  still  practiced,  though  on  a  smaller  scale,  by  us  their 
feeble  descendants.     These  magnificent  colonnades  of  basalt  are  every 


BASALTIC  COLUMNS.  455 


i;^ 


Fig.  189.  Flow  of  VitreouB  Lava  at  Mauna-Loa. 

where  attributed  to  giants.  In  Ireland,  on  the  coast  of  Antrim,  the  sum- 
mits of  40,000  prisms,  leveled  pretty  regularly  by  the  waves  of  the  sea, 
and  resembling  a  vast  paved  quay,  have  received  the  name  of  the  Giant's 
Causeway.  In  Scotland,  the  beautiful  cave  of  the  Isle  of  StalFa,  hollowed 
out  by  the  action  of  the  waves  between  two  ranges  of  basaltic  shafts,  is 
celebrated  as  the  work  of  Fingal,  the  demigod.  In  the  Sicilian  Sea,  the 
Faraglioni  Isles,  or  Isles  of  the  Cyclopes,  situated  not  far  from  Catania,  at 
the  base  of  Etna,  ai^boked  upon  by  tradition  as  the  rocks  cast  by  Poly- 
phemus on  the  ships  of  Ulysses  and  his  companions.  Many  of  these  prisms 
are  from  100  to  160  feet  high,  and  are  not  less  than  6  to  10  feet  in  thick- 
ness. Near  Fair  Head  and  the  Giant's  Causeway  some  of  the  shafts  con- 
nected with  the  perpendicular  cliff  of  the  headland  are  nearly  400  feet  in 
height.  In  the  Isle  of  Skye,  some  of  the  columns,  according  to  M'Cul- 
loch's  statement,  are  still  higher.  On  the  other  hand,  there  ai-e  also  col- 
onnades in  miniature,  each  shaft  of  which  is  not  more  than  three  quarters 
of  an  inch  to  an  inch  from  ^e  summit  to  the  base;  instances  of  these  are 
found  in  the  basalts  of  the  hill  of  Morven  in  Scotland. 

Some  geologists  have  thought  that  basaltic  columns  could  not  be  form- 
ed except  under  the  pressure  of  enormous  masses  of  water ;  but  a  com- 
•parative  study  of  these  rocks  in  different  parts  of  the  world  has  proved 
that  several  beds  of  lava  are  arranged  in  columns  at  heights  considerably 
above  the  level  of  the  sea.  In  this  colonnade-like  formation  of  lava  there 
is,  however,  no  phenomenon  which  is  entirely  peculiar  to  basalt.  Trachyte, 
also,  sometimes  assumes  this  form,  and  M.  Fouqu«3  has  discovered  a  magnif- 
icent instance  of  it  in  the  island  ofMilo,  in  which  there  is  a  cliff  composed 
of  prismatic  shafts  320  feet  in  height.  Masses  of  mud  when  dried  in  the 
sun,  the  alluvium  of  rivers,  beds  of  clay  or  tufii,  and,  in  general,  all  matter 
which,  in  consequence  of  the  loss  of  its  moisture,  passes  from  a  pasty  to  a 
solid  state,  either  in  a  state  of  nature  or  in  our  manufactories  and  dwell- 
ings, likewise  assume  a  columnar  structure  similar  to  that  of  tlie  basaltic 


456  ^^^  EARTH. 

• 
lava.  In  fact,  the  entire  mass,  when  gradually  losing  the  moisture  which 
swelled  out  its  substance,  can  not  contract  so  as  to  shift  the  position  of 
all  its  particles  toward  the  centre ;  certain  points  remain  fixed,  and  round 
eacli  of  these  the  contraction  of  a  portion  of  the  mass  takes  place.  In 
basalt,  in  particular,  it  is  the  lower  layer  which  assumes  the  columnar 
structure,  for  these  alone  cool  gently  enough  to  allow  the  phenomena  of 
contraction  to  follow  the  normal  course.  The  highest  portion  of  the  mass, 
being  deprived,  immediately  after  its  issue  from  the  earth,  of  the  caloric 
and  the  steam  which  filled  its  pores,  is  almost  immediately  transformed 
into  a  more  or  less  rough  and  cracked  mass.  But  this  very  crust  protects 
the  rest  of  the  lava  against  any  radiation,  and  serves  as  a  covering  to  the 
semi-crystalline  columns  which,  by  the  continual  contraction  of  their  parti- 
cles, are  slowly  separated  from  the  rest  of  the  mass.  When  a  section  of  a 
bed  of  basaltic  lava  has  been  laid  bare  by  the  water  of  a  I'iver,  the  waves 
of  the  ocean,  or  earthquake,  the  rough  stone  of  the  top  layers  may  be  seen 
lying,  with  or  without  any  gradual  transition,  on  a  forest  of  prisms,  some- 
times rudimentary  in  their  shape,  but  often  no  less  regular  than  if  they 
had  been  carved  out  by  the  hand  of  man.  Most  are  of  a  hexagonal  form; 
othei-s,  which  were  probably  subject  to  less  favorable  conditions,  have 
four,  five,  or  seven  faces ;  but  all  are  definitely  separated  from  one  another 
by  their  particles  gathering  round  the  central  axis.  Mr.Poulett  Scrope 
describes  a  fact  which  proves  the  enormous  power  of  this  conti'actile  force. 
The  colonnade  of  Burzet,  in  Vivarais,  contains  numm-ous  nodules  of  oli- 
vine, many  of  which  are  as  large  as  a  man's  fist;  a^^in  spite  of  their  ex- 
treme hardness,  have  been  divided  into  two  pieces,  each  fixed  in  one  of 
two  adjacent  columns.  Although  the  two  corresponding  surfaces  have 
been  polished  by  the  infiltration  of  water,  it  is  impossible  to  doubt  that 
the  two  separate  portions  were  not  once  joined  in  the  same  nodule. 

As  natural  philosophers  have  verified  by  experiments  on  various  viscous 
substances,  basaltic  shafts  are  always  formed  perpendicularly  to  the  sur- 
face of  refrigeration.  •  Now,  this  surface  being  inclined,  according  to  the 
locality,  in  a  diversity  of  ways,  the  result  is,  thj^t  the  columns  may  assume 
a  great  variety  of  directions  in  their  position.  Although  most  of  them 
are  vertical,  on  account  of  the  cooling  taking  place  in  an  upward  direc- 
tion, others,  as  at  St.  Helena,  take  a  horizontal  direction,  and  resemble 
trunks  of  trees  heaped  upon  a  wood-pile.  In  other  places,  as  at  the  Coupe* 
d'Ayzac  in  Auvergne,  the  columns  of  a  denuded  cliff  are  arranged  in  the 
fonn  of  a  fan,  so  as  to  lean  regularly  on  the  wall  of  the  cliff  as  well  as  on 
the  ground  of  the  valley.  At  Samoskoe,  in  Hungary,  a  sheet  of  columnar 
basalt,  very  small  at  its  origin,  spreads  out  from  the  top  of  a  rock  like  the 
water  of  a  cascade,  and  hangs  suspended  over  a  precipice,  resembling  a 
cupola  which  has  lost  its  base.  Elsewhere  masses  of  basaltic  pillars  radi- 
ate in  every  direction  like  the  weapons  in  an  immense  trophy  of  arms. 

An  exact  prismatic  form  is  not,  however,  the  only  shape  assumed  by  the 
cooling  lava.  The  phenomenon  of  contraction  takes  place  in  different  ways, 
according  to  the  nature  of  the  ei'upted  matter,  the  declivity  of  the  slopes, 


BASALTIC  COLUMNS.  45>Jr 

and  all  the  other  surrounding  circumstances.  Thus,  in  consequence  of  the 
sinking  of  the  rock,  most  basaltic  prisms  exhibit  at  intervals  a  kind  of 
joint,  which  gives  the  columns  a  kind  of  resemblance  to  gigantic  bamboos. 
In  some  lavas  these  joints  are  so  numerous,  and  the  edges  of  the  stone  are 
so  eaten  away  by  the  weather,  that  the  shafts  are  converted  into  piles  of 
spheroids  of  a  more  or  less  regular  form.  At  the  volcano  of  Bertrich,  in 
the  Eifel,  one  might  fancy  them  a  heap  of  cheeses ;  whence  comes  the 
name  of  "  Cheese  Cave,"  which  is  given  to  one  of  the  caverns  which  opens 
in  the  flow  of  lava.  Sometimes,  too,  crystals  scattered  about  in  the  midst 
of  the  mass  have  served  as  nuclei  to  globular  concretions  formed  of  nu- 
merous concentric  layers.  Lastly,  many  currents  of  molten  matter  pre- 
sent a  tabular  or  schistose  structure,  caused,  like  that  of  slate,  by  the 
pressure  of  the  superincumbent  masses. 


458  ^^^  EARTH. 


CHAPTER  LXVn. 

SOUECES    OF    LAVA  ;    STROMBOLI  ;    MASAYA  ;    ISALCO  ;    KILAUEA.  —  LATERAL 
CREVICES   IN  VOLCANOES. ERUPTION   AND   MOTION   OF  LAVA. 

Although  lava,  when  cooled,  is  easy  enough  to  study,  it  is  more  diffi- 
cult to  observe  with  any  exactitude  the  molten  matter  immediately  on  its 
exit  from  the  craters  or  fissures ;  besides  this,  the  opportunities  for  study 
which  are  ofiered  to  savants  are  sometimes  very  dangerous.  Long  years 
often  elapse  before  an  inquirer  can  notice  at  his  ease,  and  without  fear  of 
sudden  explosions,  the  mouths  of  Etna  or  Vesuvius  filling  up  to  the  brink 
with  boiling  lava. 

Stromboli  is  the  only  volcano  in  Europe  in  which  this  phenomenon  oc- 
curs regularly  at  closely-recurring  intervals,  sometimes  of  only  five  min- 
utes, or  even  more  frequently.  When  an  observer  stands  on  the  highest 
edge  of  the  crater,  he  sees,  about  300  feet  below  him,  the  waves  of  a  mat- 
ter which  shines  like  molten  iron,  and  tosses  and  boils  up  incessantly; 
sometimes  it  swells  up  like  an  enormous  blister,  which  suddenly  bursts, 
darting  forth  eddies  of  vapor  accompanied  by  solid  fragments.  For  cen- 
turies past  the  lava  has  never  ceased  to  boil  in  the  cavity  of  Stromboli, 
and  it  is  but  very  rarely  that  a  period  of  even  a  few  hours  elapses  withotft 
molten  matter  overflowing.  Thus  the  crater,  which,  during  the  day,  is 
white  with  steam,  and  during  the  night  red  with  the  glare  of  the  lava,  has 
served  as  a  light-house  for  mariners  ever  since  the  first  vessel  ventured 
upon  the  Tyrrhenian  Sea. 

In  Nicaragua,  to  the  north  of  the  Great  Lake,  the  volcano  of  Masaya 
(or  "Devil's  Mouth")  presents  a  spectacle  similar  to  that  of  Stromboli,  but 
grander,  and  perhaps  still  more  regular.  After  having  remained  in  a  state 
of  repose  for  nearly  two  centuries,  from  1670  to  1853,  the  monster — which 
has  received  the  name  it  bears  from  the  frightful  turbulence  of  its  burning 
waves — resumed  all  its  former  activity.  In  this  crater  the  enormous  bub- 
bles of  lava,  which  ascend  from  the  bottom  of  the  abyss  and  throw  out  a 
shower  of  burning  stones,  break  forth  in  a  general  way  every  quarter  of 
an  hour. 

The  volcano  of  Isalco,  not  far  from  Sonsonate,  in  the  State  of  San  Salva- 
dor, is  also  one  of  the  most  curious  on  account  of  its  regularity.  Its  first 
breaking  out  was  noticed  on  the  29th  of  March,  1783,  and  since  this  date* 
it  has  almost  always  continued  to  increase  in  size  by  throwing  outside  its 
cavity  ashes  and  stones.  Some  of  its  eruptions,  remarkable  for  their  com- 
parative violence,  have  been  accompanied  by  flows  of  lava ;  but,  generally, 
the  crater  of  Isalco  confines  itself  to  hurling  burning  matter  to  a  height 

*  M.  Squier  gives  another  date,  the  23d  of  February,  1770,  but  it  is  probably  an  error. 


Fig.  191.  Crater  of  Mauna-Loa. 


CRATER  OF  KILAUEA. 


461 


of  39  to  46  feet  above  its  crater :  explosions  follow  one  another  at  inter- 
vals of  every  two  minutes.*  The  total  elevation  of  the  cone  of  debris 
above  the  village  of  Isalco  being  735  feet,  and  the  slope  of  the  side  of  the 
mass  being,  on  the  average,  35  degrees,  M.  von  Seebach,  one  of  the  observ- 
ers of  the  volcano,  has  been  able  to  calciilate  approximately  the  bulk  and 
re<*ular  increase  of  the  mountain.  In  1865  the  mass  oi  debris  was  about 
35,000,000  of  cubic  yards,  giving  an  increase  of  about  49},000  cubic  yards 
every  year,  or  56  cubic  yards  every  hour.  The  volcano,  therefore,  might 
be  looked  upon  as  a  gigantic  hour-glass.f 


Fig.  190.  Craters  of  Eilanea. 


Of  all  the  craters  in  the  world,  the  one  which  most  astonishes  those  who 
contemplate  it  is  the  crater  of  Kilauea,  in  the  island  of  Hawaii.  This  vol- 
canic outlet  opens  at  more  than  3900  feet  of  elevation  on  the  sides  of  the 
gi-eat  mountain  of  Mauna-Loa,  which  is  itself  crowned  by  a  magnificent 
funnel-shaped  crater  2735  yards  across  from  one  brink  to  the  other.  The 
elliptical  crater  of  Kilauea  is  no  less  than  3  miles  in  length  and  7  miles  in 
circumference.  The  hollow  of  this  abyss  is  filled  by  a  lake  of  lava,  the 
level  of  which  varies  from  year  to  year,  sometimes  rising  and  sometimes 
falling  like  water  in  a  well.  In  a  general  way,  it  lies  about  600  to  900 
feet  below  the  outer  edge,  and,  in  order  to  study  its  details,  it  is  necessary 
to  get  on  to  a  ledge  of  black  lava  which  extends  round  the  whole  circum- 
ference of  the  gulf;  this  is  the  solidified  edge  of  a  former  sheet  of  molten 
matter,  similar  to  those  circular  benches  of  ice  which,  in  northern  coun- 
tries, border  the  banks  of  a  lake,  and  even  in  spring  still  mark  the  level 
the  water  has  sunk  from.  The  surface  of  the  sea  of  fire  is  generally  cov- 
ered by  a  thick  crust  over  its  whole  extent ;  here  and  there  the  red  lava- 

*  Moritz  Wagner ;  Carl  von  Scherzer.  f  Zeitschri/l  Jiir  Erdkunde,  iSQ6.    , 


462  ^^^  EARTH. 

waves  spring  up  like  the  water  of  a  lake  through  the  broken  ice.  Jets  of 
vapor  whistle  and  hiss  as  they  escape,  darting  out  showers  of  burning 
scoriae,  and  forming  cones  of  ashes  on  the  crust  60  to  100  feet  in  height, 
which  are  so  Inany  volcanoes  in  miniature.  Intense  heat  radiates  from 
the  immense  crater,  and  a  kind  of  hot  blast  makes  its  way  through  all  the 
chinks  in  the  vertical  walls  of  the  sides.  In  the  midst  of  the  hot  vapors, 
one  feels  as  if  lost  in  a  vast  furnace.  During  the  night-time  an  observer 
might  fancy  himself  surrounded  with  flames ;  the  atmosphere  itself,  col- 
ored by  the  red  reflection  of  the  vent-holes  of  the  volcano,  seems  to  be  all 
on  fire. 

jt6aS 
Fig.  192.  Section  across  the  Craters  of  Kilauea. 

The  level  oi  the  fire-lake  of  Kilauea  is  incessantly  changing.  In  propor- 
tion as  fresh  lava  issues  forth  from  the  subterranean  furnace,  the  broken 
crust  affords  an  outlet  to  other  sheets  of  molten  matter  and  fresh  heaps  of 
scorise,  and  gradually  the  boiling  mass  rises  from  ledge  to  ledge,  and  ulti- 
mately reaches  the  upper  edge  of  the  basin.  Sooner  or  later,  however, 
the  level  rapidly  sinks.  The  fact  is,  that  the  burning  mass  contained  in 
the  depths  of  the  abyss  gradually  melts  the  lower  walls  of  solid  lava; 
these  walls  ultimately  give  way  at  some  weak  points  in  their  circumfer- 
ence, a  crevice  is  produced  in  the  outer  face  of  the  volcano,  and  the  liquid 
matter,  "  drawn  off"  like  wine  from  a  vat,  rushes  through  the  opening 
made  for  it.  The  flow  increases  the  orifice  by  the  action  of  its  weight  on 
the  sill  of  the  opening,  and  by  melting  the  rocks  .vhich  oppose  its  passage, 
and  then,  running  down  over  the  slopes,  flows  into  the  sea,  forming  prom- 
ontories on  the  shore.  In  1 840  the  crater  was  full  to  the  brink,  when  a 
crack  suddenly  opened  in  the  side  of  the  mountain.  This  fissure  extended 
to  a  distance  of  131  feet  from  its  starting-point,  and  vomited  forth  a 
stream  of  lava  37  miles  long  and  16  miles  wide,  which  entirely  altered  the 
outline  of  the  sea-coast,  and  destroyed  all  the  fish  in  the  adjacent  waters. 
Mr.  Dana  estimated  the  total  mass  of  this  enormous  flow  as  equal  to 
7,200,000  cubic  yards — that  is,  to  a  solid  body  fifty  times  as  great  as  the 
quantity  of  earth  dug  out  in  cutting  through  the  Isthmus  of  Suez.  The 
enormous  basin  of  Kilauea,  1476  feet  deep,  remained  entirely  empty  for 
some  time,  and  the  former  lake  of  lava  left  no  other  trace  of  its  existence 
than  a  solid  ledge  like  those  which  had  been  formed  at  the  time  of  pre- 
vious eruptions.  Since  this  date  the  great  caldron  of  lava  has  been  several 
times  filled  and  several  times  emptied,  either  altogether  or  in  part. 

Almost  all  the  volcanoes  which  rise  to  a  great  height,  get  rid,  like  Ki- 
lauea, of  their  ovei*flow  of  lava  through  fissures  which  open  in  their  side 
walls.  In  fact,  the  column  of  molten  matter  which  the  pressure  of  the 
gas  beneath  raises  in  the  pipe  of  the  crater  is  of  an  enormous  weight,  and 


LAVA-FLOWS.  463 

every  inch  it  ascends  toward  the  mouth  of  the  crater  represents  an  expense 
of  force  which  seems  prodigious.  The  more  or  less  hypothetical  calcula- 
tions which  have  been  made  as  to  the  degree  of  pressure  necessary  for  the 
steam  to  be  able  to  act  on  the  lava-furnace  lead  to  the  belief  that  the  out- 
let-conduits of  volcanoes,  and  consequently  the  mass  of  liquid  stone  to  be 
lifted,  are  not  less  than  nine  miles  in  depth.*  Various  geologists — among 
others,  Sartorius  von  Waltershausen,  the  great  explorer  of  Etna — believe 
that  the  volcano-shafts  are  of  a  still  more  considerable  depth.  The  rocks 
of  the  terrestrial  surface,  limestone,  granite,  quartz,  or  mica,  are  of  a  spcj^ 
cific  gravity  two  and  a  half  times  superior  to  that  of  water,  while  the 
planet  itself,  taken  as  a  whole,  weighs  nearly  five  and  a  half  times  as  much 
as  the  same  mass  of  distilled  water;  the  density  of  the  interior  layers 
must  therefore  increase  from  the  circumference  to  the  centre.  With  re- 
gard to  the  proportion  of  this  increase,  it  is  established  by  a  calculation, 
the  whole  responsibility  of  which  must  rest  upon  its  authors.  Baron  Wal- 
tershausen has  ascertained,  by  means  of  a  great  number  of  weighings,  that 
the  lava  of  Etna  and  that  of  Iceland  have  a  specific  gravity  of  2*911.  The 
presumed  consequence  of  this  fact  is  that  the  rocks  thrown  out  by  the 
volcanoes  of  Sicily  and  Iceland  proceed  from  a  depth  of  77  to  78  miles  (?). 
Thus  the  shaft  which  opens  at  the  bottom  of  the  crater  of  Etna  would  be 
no  less  than  77  miles  deep,  and  the  lava  which  boils  in  this  abyss  would 
be  lifted  by  a  force  of  36,000  atmospheres,  an  idea  altogether  incompre- 
hensible by  our  feeble  imaginations.  There  would,  then,  be  nothing  aston- 
ishing in  the  fact  that  a  mass  of  lava,  which  is  sufficiently  heavy  to  bal- 
ance a  pressure  of  this  kind,  should,  in  a  great  many  eruptions,  melt  and 
break  through  the  weaker  parts  of  its  walls,  instead  of  ascending  some, 
hundreds  or  thousands  of  feet  higher,  so  as  to  run  out  over  the  edge  of 
the  upper  crater. 

When  the  side  of  the  mountain  opens,  and  affords  a  passage  to  the  lava, 
the  fissure  is  always  perceptibly  vertical,  and  those  which  are  continued 
to  the  summit  pass  through  the  very  mouth  of  the  volcano.  In  a  general 
way,  these  fissures  of  eruption  are  of  considei-able  length,  and  are  suffi- 
ciently wide  to  form  an  impassable  precipice.  Before  these  fissures  be- 
come obliterated  by  the  lava  or  by  other  debris — such  as  the  snow  and 
earth  of  avalanches — they  may  be  traced  out  by  the  eye  as  deep  furrows 
hollowed  out  on  the  mountain  side.  In  1669  the  lateral  fissure  of  Etna 
extended  over  more  than  two  thirds  of  the  southern  side — from  the  plains 
of  Nicolosi  to  the  terminal  gulf  of  the  great  crater.  In  like  manner,  in 
the  Isle  of  Jan  Mayen,  the  volcano  of  Beerenberg,  7513  feet  high,  presents 
from  top  to  bottom  a  long  depression  filled  up  with  snow,  which  is  noth- 
ing else  than  a  fissure  of  eruption.  On  other  mountains,  especially  in 
Montserrat,  Guadaloupe,  and  Martinique,  these  fissures  have  assumed  such 
dimensions  that  the  peaks  themselves  have  been  completely  split  in  two. 

Through  outlets  of  this  kind  the  lava  jets  out,  first  making  its  appear- 
ance at  the  upper  part,  where  the  declivity  is  generally  steeper,  then 

*  Buff,P%tt*  derErde. 


464  ^^^  EARTH. 

springing  out  below  on  the  more  gentle  slopes  of  the  lower  regions  of  the 
mountain. 

At  the  source  itself  the  lava  is  altogether  fluid,  and  flows  with  consid- 
erable speed — sometimes,  on  steep  slopes,  faster  than  a  horse  can  gallop ; 
but  the  course  of  the  molten  stone  soon  slackens,  and  the  liquid,  hitherto 
dazzling  with  its  light,  is  covered  by  brown  or  red  scorije,  like  those  of 
iron  just  come  out  of  a  furnace.  These  scoriae  come  together,  and,  com- 
bining, soon  leave  no  interstices  between  them  beyond  narrow  vent-holes, 
through  which  the  molten  matter  escapes.  The  scoriae  then  form  a  crust, 
which  is  incessantly  breaking  with  a  metallic  noise,  but  gradually  consoli- 
dates into  a  perfect  tunnel  round  the  river  of  fire ;  this  is  the  cheire^  thus 
named  on  account  of  the  asperities  which  bristle  on  its  surface.  Any  one 
may  safely  venture  on  the  arch-shaped  crust,  although  only  a  few  inches 
above  the  mass  in  state  of  fusion,  without  any  fear  of  being  burnt,  just 
as  in  winter  we  trust  ourselves  on  the  sheets  of  ice  which  cover  a  running 
stream.  The  pressure  of  the  lava  succeeds  in  breaking  through  its  shell 
only  at  the  lower  parts  of  its  flow,  in  spots  where  the  waves  of  burning 
stone  fall  with  all  their  weight.  Then  the  envelope  is  suddenly  ruptured, 
and  the  mass  springs  out  like  water  from  a  sluice,  pushing  before  it  the 
resounding  scoriae,  and  swelling  out  gently  in  the  form  of  an  enormous 
blister ;  it  then  again  becomes  covered  with  a  solid  crust,  which  is  again 
broken  through  by  a  fresh  effort  of  the  lava.  Thus  the  river,  surround- 
ing itself  with  dikes  which  it  constantly  breaks  through,  gradually  de- 
scends over  the  slopes,  terrible  and  inexorable,  so  long  as  the  original 
stream  does  not  cease  to  flow.  The  only  means  of  diverting  the  current 
is  to  modify  the  incline  in  front  of  it — either  by  opposing  obstacles  to  it 
to  throw  it  to  either  side,  or  by  preparing  a  road  for  it  by  digging  deep 
trenches,  or  by  opening  up  above  some  lateral  outlet  for  the  pent-up  lava. 
In  1669,  at  the  time  of  the  great  eruption  which  threatened  to  swallow  up 
Catania,  all  these  various  means  were  adopted  in  order  to  save  the  town. 
On  one  side  the  inhabitants  worked  at  consolidating  the  rampart,  and 
placed  obstacles  across  the  path  of  the  current  to  turn  it  toward  the 
south.  Other  workmen,  furnished  with  shovels  and  mattocks,  ascended 
along  the  edge  of  the  flow,  and,  in  spite  of  the  resistance  offered  by  the 
peasants,  tried  to  pierce  through  the  shell  of  scoriae,  and  thus,  by  tapping 
the  stream,  to  open  fresh  outlets  for  the  molten  matter.  These  means  of 
defense  partly  succeeded,  and  the  terrible  current  which,  at  its  source 
near  Nicolosi,  had  been  able  to  melt  and  pierce  through  the  volcanic  cone 
of  Monpilieri  at  its  thickest  point  (this  cone  standing  in  its  path),  was 
tunied  from  its  course  toward  the  centre  of  Catania,  and  destroyed  noth- 
ing but  the  suburbs. 

The  radiation  from  the  lava  being  arrested  by  the  crust  of  scoriae,  which 
is  a  very  bad  conductor  of  heat,  the  temperature  of  the  air  surrounding  a 
flow  of  lava  rises  but  very  slightly.     The  Neapolitan  guides  have  no  fear 

*  Or  ierre.!  in  Italian  sciara :  these  are  sj-nonyms  of  the  word  scie  (saw)  in  the  French  of 
the  present  day. 


LAVA  FLOWS.  465 

in  approaching  the  Vesuvian  lava  in  order  to  stamp  the  rough  medals 
made  of  it,  which  they  sell  to  foreigners.  At  a  distance  of  a  few  yards 
from  the  vent-holes  in  the  cheire  the  trees  of  Etna  continue  to  grow  and 
blossom,  and  some  clumps,  indeed,  may  be  seen  flourishing  on  an  islet  of 
vegetable  earth  lying  between  two  branches  of  a  flow  of  burning  lava. 
And  yet,  by  a  contrast  which  at  first  sight  seems  incomprehensible,  it 
sometimes  happens  that  trees  which  are  distant  from  any  visible  flow  of 
molten  matter  suddenly  wither  and  die.  Thus,  in  1852,  at  the  time  of  the 
great  eruption  from  the  Val  del  Bove,  on  the  eastern  slopes  of  Mount  Etna, 
vineyards  and  vines,  covering  a  considerable  area,  and  situated  at  a  dis- 
tance of  more  than  half  a  mile  below  the  front  of  the  flow,  were  suddenly 
dried  up,  just  as  if  the  blast  of  a  fire  had  burnt  up  their  foliage.  In  order 
to  explain  this  curious  phenomenon,  it  is  necessary  to  admit  that  some 
rivulets  of  the  great  lava-river  must  have  penetrated  under  the  earth 
through  the  fissures  of  the  soil,  and  have  filled  up  a  subterranean  cavity 
in  the  mountain  exactly  below  the  vineyards  that  were  destroyed:  the 
roots  being  consumed,  or  deprived  of  the  necessary  moisture,  the  trees 
themselves  could  not  do  otherwise  than  perish.* 

On  lofty  mountains  in  a  state  of  eruption,  the  masses  of  snow  and  ice, 
which  are  covered  by  the  fiery  cuiTcnts  which  issue  from  the  volcanic  fis- 
sures, do  not  always  melt,  and  some  have  been  preserved  under  the  scoriae 
for  centuries,  or  even  thousands  of  years.  Lyell  has  discovered  them  un- 
der the  lava  of  Etna,  American  geologists  under  the  masses  thrown  out 
by  the  crater  of  Mount  Hooker,  Darwin  under  the  ashes  in  Deception  Isl- 
and, in  the  Tierra  del  Fuego,  M.  Philippi  under  the  flows  of  the  volcano 
Nuevo  de  Chillan,f  which  in  1861  erupted  through  a  glacier.  There  every 
bed  of  snow  which  falls  during  the  winter  remains  perfect  under  the  coat 
of  burning  dust  which  is  ejected  from  the  outlet  of  eruption,  and  sections 
made  througj^the  mass  of  debris  show  for  a  great  depth  the  alternate 
black  and  wl^re  strata  of  the  volcanic  ashes  and  the  snow.  In  1860  the 
crater  of  the  mountain  of  Kutlagaya,  in  Iceland,  hurled  out  simultaneous- 
ly into  the  air  lumps  of  lava  and  pieces  of  ice  all  intermingled  together.J 

In  like  manner,  the  immense  flow  of  lava  in  Iceland  have  left  in  a  per- 
fect state  of  preservation  the  trunks  of  the  Sequoias^  and  other  American 
trees,  which  adorned  the  surface  of  the  island  during  the  ages  of  the  Ter- 
tiary epoch,  at  a  time  when  the  mean  temperature  of  this  country  was 
48°  (Fahr.),  that  is,  42°  to  44°  above  that  which  it  is  at  present.§  Al- 
though the  radiation  from  the  lava  is  so  slight  that  it  neither  melts  the 
ice  nor  burns  the  trunks  of  buried  trees,  yet,  on  the  other  hand,  the  heat 
and  fluidity  of  the  lava  are  maintained  in  the  central  part  of  the  flow  for 
a  very  considerable  number  of  years.  Travelers  state  that  they  have 
found  deeply-buried  lava  which  was  still  burning  after  it  had  remained 
for  a  century  on  the  mountain  side. 

*  LyeW,  Philosophical  Transactiong,  18')8. 

+  Mittheilungen  von  Petermann,  vol.  vii.,  18G3.  X  Wallich,  North  Atlantic  Sea-hed. 

§  Carl  Vogt,  Nordfuhrt. 

Go 


466 


THE  EARTH. 


••■•''i!8;\\\\#)/5^<!P' 


Fig.  193.  Nevado  de  Chilian. 

Although  the  lava  covers  up  and  often  preserves  the  snow  and  the  ice, 
which  are  doubtless  defended  against  the  heat  by  a  cushion  of  spheroidal 
particles  of  humidity,  it  immediately  converts  into  steam  the  water  with 
which  it  comes  in  contact.  The  liquid  mass,  being  suddenly  augmented 
to  about  1800  times  its  former  volume,  explodes  like  an  enormous  bomb- 
shell, and  hurls  away,  like  projectiles,  all  the  objects  which  surround  it. 
A  serious  occurrence  of  this  kind  is  recorded,  which  took  place  in  1843,  a 
few  days  after  the  formation  of  a  fissure  in  Mount  Etna,  from  which  a  cur- 
rent of  molten  matter  issued,  making  its  way  toward  the  plain  of  Bronte. 
A  crowd  of  spectators,  who  had  come  from  the  town,  were  examining 
from  a  distance  the  threatening  mass,  the  peasants  were  cubing  down  the 
trees  ;n  their  fields,  others  were  carrying  off  in  haste  the  ^rods  from  their 
cottages,  when  suddenly  the  extremity  of  the  flow  was  seen  to  swell  up 
like  an  enormous  blister,  and  then  to  burst,  darting  forth  in  every  direc- 
tion clouds  of  steam  and  volleys  of  burning  stones.  Every  thing  was  de- 
stroyed by  this  tein-ible  explosion — trees,  houses,  and  cultivated  ground ; 
and  it  is  said  that  sixty-nine  persons,  who  were  knocked  down  by  the  con- 
cussion, perished  immediately,  or  in  the  space  of  a  i^w  hours.  This  disas- 
ter was  occasioned  by  the  negligence  of  an  agriculturist,  who  had  not 
emptied  the  reservoir  on  his  farm ;  the  water,  being  suddenly  converted 
irito  steam,  had  caused  the  lava  to  explode  with  all  the  force  of  gun- 
powder. 

The  quantity  of  molten  matter  which  is  ejected  by  a  fissure  in  one  sin- 
gle eruption  is  enormous.  It  is  known  that  the  current  of  Kilauea,  in 
1840,  exceeded  6550  millions  of  cubic  yards.  That  which  proceeded  from 
Mauna-Loa  in  1835  produced  a  still  larger  quantity  of  lava,  and  extended 
as  far  as  a  point  76  miles  from  the  crater.  Flows  of  this  kind  are  certainly 
rare ;  but  there  are  some  recorded  in  the  earth's  history  which  are  still 


LAVA-FLOWS.  467 

more  considerable.  Thus  the  volcano  of  Skaptar-Jokul,  in  Iceland,  was 
cleft  asunder  in  1 V83,  and  gave  vent  to  two  rivers  of  fire,  each  of  which 
filled  up  a  valley;  one  attained  a  length  of  50  miles,  with  a  breadth  of  15 
miles ;  the  other  was  of  less  dimensions,  but  the  depth  of  the  mass  was  in 
some  places  as  much  as  492  feet.  A  subterranean  fissure,  99  miles  in 
length,  which  cleaves  in  two  the  ground  of  Iceland,  was  doubtless  filled 
up  with  lava  along  its  entire  length,  for  hillocks  of  eruptions  sprung  up 
on  various  points  of  this  straight  line.  It  has  been  calculated  that  the 
whole  of  the  lava  evacuated  by  the  Skaptar  in  this  great  eruption  was  not 
less  in  bulk  than  655,000  millions  of  cubic  yards,  a  mass  equivalent  to  the 
whole  volume  of  Mont  Blanc ;  it  would  be  a  quantity  suflicient  to  cover 
the  whole  earth  with  a  film  of  lava  0'0393  inch  in  thickness.  As  to  the 
celebrated  flow  from  the  Monti  Rossi,  which  threatened  to  destroy  Catania 
in  1669,  it  seems  very  trifling  in  comparison ;  it  contained  a  mass  of  molten 
stone  which  was  estimated  at  1310  millions  of  cubic  yards.  On  how  tri- 
fling a  scale,  therefore,  are  these  ordinary  eruptions  compared  with  the 
surface  of  the  globe!  They  are,  however,  phenomena  perceptible  enough 
to  man,  in  all  his  infinite  littleness. 


4(58  •      THE  EARTH. 


CHAPTER  LXVm. 

VOLCANIC  PROJECTILES. —  EXPLOSIONS  OF  ASHES. —  SUBORDINATE  VOLCA- 
NOES.—  MOUNTAINS  REDUCED  TO  DUST. —  FLASHES  AND  FLAMES  PRO- 
CEEDING  FROM   VOLCANOES. 

TuE  lava  swelling  up  in  enormous  blisters  above  the  fissures  from  wLicli 
it  flows  in  a  current  over  the  slopes  is  far  from  being  the  only  substance 
ejected  from  volcanic  mountains.  When  the  pent-up  vapor  escapes  from 
the  crater  with  a  sudden  explosion,  it  carries  with  it  lumps  of  molten  mat- 
ter, which  describe  their  curve  in  the  air,  and  fall  at  a  greater  or  less  dis- 
tance on  the  slope  of  the  cone,  according  to  the  force  with  which  they 
were  ejected.  These  are  the  volcanic  projectiles,  the  immense  showers  of 
which,  traced  in  lines  of  fire  on  the  dark  sky,  contribute  so  much  during 
the  night-time  to  the  magnificent  beauty  of  volcanic  eruptions.  These 
projectiles  have  already  become  partially  cooled  by  their  radiation  in  the 
air,  and  when  they  fall  are  already  solidified  on  the  outside,  but  the  in- 
side nucleus  remains  for  a  long  time  in  a  liquid  or  pasty  state.  The  form 
of  these  projectiles  is  often  of  an  almost  perfect  regularity.  Each  sphere 
is  in  this  case  composed  of  a  series  of  concentric  envelopes,  which  have 
evidently  been  arranged  in  the  order  of  their  specific  gravity  during  the 
flight  of  the  projectile  through  the  air.  The  dimensions  of  these  projec- 
tiles vary  in  each  eruption ;  some  of  them  are  one  or  more  yards  in  thick- 
ness ;  others  are  nothing  but  mere  grains  of  sand,  and  are  carried  by  the 
wind  to  great  distances. 

In  most  eruptions,  these  balls  of  lava,  still  in  a  fluid  and  burning  state, 
constitute  but  a  small  part  of  the  matter  thrown  out  by  the  mountain. 
The  largest  proportion  of  the  stones  ejected  proceed  from  the  walls  of  the 
volcano  itself,  which  break  up  under  the  pressure  of  the  gas,  and  fly  ofi"  in 
volleys,  mingled  with  the  products  of  the  new  eruption.  This  is  the  origin 
of  the  dust  or  ashes  which  some  craters  vomit  out  in  such  large  quantities, 
which,  too,  are  the  cause  of  such  terrible  disasters.^ 

When  the  impetus  of  the  gas  confines  itself  to  forming  a  fissure  in  the 
side  of  the  mountain,  the  fi-agments  of  rocks  which  are  broken  up  and  re- 
duced to  powder  are  comparatively  small  in  quantity.  They  are  projected 
in  clouds  out  of  the  fissure,  and,  falling  like  hail  round  the  orifice,  are  grad- 
ually heaped  up  in  the  form  of  a  cone  on  the  side  of  the  mountain  from 
which  they  arose.  In  Europe  the  enomious  circumference  o^Etna  pre- 
sents more  than  700  of  these  subordinate  volcanoes,  some  scailRy  higher 
than  an  Esquimaux  hut,  and  others,  like  the  Monti  Rossi,  Monte  Minardo, 
Monte  Ilici,  several  hundred  yards  high,  and  more  than  half  a  mile  wide  at 
the  base.     There  are  some  which  are  entirely  sterile,  or  covered  only  by  a 


ExrLOsioy:s  of  ashes. 


469 


scanty  vegetation  of  broona,  and  are  marked  out  by  a  red,  yellow,  or  even 
black  color  on  the  main  body  of  Etna ;  those  situated  on  the  lower  slopes 
are  covered  with  trees  or  planted  with  vines,  and  sometimes  contain  ad- 
mirable crops  in  the  very  cavity  on  their  summit.  These  cones  of  ashes, 
springing  up  like  a  progeny  on  the  vast  sides  of  their  mother  mountain, 
give  to  Etna  a  singular  appearance  of  vital  personality  and  of  creative 
energy.  The  same  phenomenon  occure  on  the  volcanoes  of  Hawaii,  which 
carry  on  their  declivities  thousands  of  subordinate  cones. 


Fig.  194.  RegalarCoue  of  Ashes. 


Fig.  11)6.  Coue  of  Ashes  ino<1itledb.v  the  WiucL 


In  the  formation  of  these  hillocks  a  real  division  of  labor  takes  place. 
The  rocks  and  heavier  stones  fall  either  on  the  edge  of  the  crater  or  in  the 
gulf  itself.  The  ashes  and  light  dust  are  shot  up  to  a  much  great^ieight, 
;*nd,  hurried  along  by  the  impulse  of  the  wind,  fall  far  and  wide,  like  the 
chaff  of  corn  winnowed  in  a  threshing-floor.  Thus  the  slope  of  the  cone 
toward  which  the  wind  directs  the  ashes  is  always  more  elongated,  and 
rises  to  a  greater  height  on  the  edge  of  the  crater.     On  Etna,  where  the 


Fig.  196.  Cone  of  Etna  and  Val  del  Bove. 


wind  generally  blows  in  the  direction  of  west  to  east,  the  eastern  slope  of 
the  .hillocks  is  more  developed  than  on  the  opposite  side.  It  must,  per- 
haps, be  attributed  to  the  action  of  the  wind  blowing  on  the  heights,  and 


470  ^-^^  EARTH. 

not,  as  Siemsen,*  the  geologist,  supposes,  to  the  obliquity  of  the  shaft  of 
the  crater,  that  all  the  scoriae  and  ashes  fall  to  the  north  of  the  orifice  of 
the  volcano  Nuevo  de  Chilian,  in  Chili. 

The  phenomena  which  take  place  when  the  ashes  issue  from  the  mouth 
of  the  crater  itself  do  not  differ  from  those  which  are  observed  at  the  out- 
lets in  fissures.  In  the  former  case,  however,  the  mass  of  rocks  reduced 
to  powder  is  so  considerable  that  the  rain  of  ashes  assumes  all  the  propor- 
tions of  a  cataclysm.  It  has  sometimes  happened  that,  during  a  paroxysm 
of  volcanic  energy,  the  whole  summit  of  a  mountain,  for  a  depth  of  several 
thousands  of  feet,  has  been  hurled  into  the  air,  mingled  with  a  cloud  of 
vapor  and  the  smoke  of  burning  lava.  Thus  Etna,  if  we  are  to  believe 
^lianus,  was  once  much  loftier  than  it  is  in  our  time,  and  on  the  north  of 
the  present  terminal  cone  there  may,  in  fact,  be  noticed  a  kind  of  platform 
which  seems  to  have  been  the  base  of  a  summit  twice  as  high  as  the  pres- 
ent creak  The  whole  of  the  Val  del  Bove  is  probably  an  empty  space  left 
by  the  cusappearance  of  a  former  cone. 

With  regard  to  Vesuvius,  it  is  known  that,  in  the  year  79  of  the  present 
era,  the  whole  of  that  part  of  the  mountain  which  was  turned  toward  the 
sea  was  reduced  to  powder,  and  that  the  debris  of  the  cone,  nothing  of 
which  now  remains  except  the  semicircular  inclosure  of  La  Somraa,  buried 
three  towns  and  a  vast  extent  of  plain.  The  ashes  and  dust,  mingled  with 
white  vapor  rising  in  thick  eddies,  ascended  in  a  column  to  a  point  far 
above  the  summit  of  the  volcano,  until,  having  reached  those  regions  of 
the  atmosphere  where  the  rarefied  air  could  no  longer  sustain  them,  they 
spread  out  into  a  wide  umbrella-like  shape,  the  falling  dust  of  which  ob: 
scured  the  sky.  Pliny  the  Younger  compared  this  vault  of  ashes  and 
smoke  to  the  foliage  of  an  Italian  pine  curving  at  an  immense  height  over 
the  mountain.  Since  this  memorable  epoch  the  height  of  the  column  of 
vapor  has  been  measured  which  has  issued  from  Vesuvius  at  the  time  of 
several  great  eruptions,  and  it  has  been  sometimes  found  that  it  reached 
23,000  to  26,000  feet ;  that  is,  six  times  higher  than  the  summit  of  the  vol- 
cano itself 

One  of  these  explosions  of  entire  summits  which  caused  most  terror  in 
modern  times  was  that  of  the  volcano  of  Coseguina,  a  hillock  of  about  500 
feet  high,  situated  on  a  promontory  to  the  south  of  the  Bay  of  Fonseca,  in 
Central  America.  The  debris  hurled  into  the  air  spread  over  the  sky  in  a 
homble  arch  several  hundreds  of  miles  in  width,  and  covered  the  plains 
for  a  distance  of  25  miles  with  a  layer  of  dust  at  least  16  feet  thick.  At 
the  very  foot  of  the  hill  the  headland  advanced  787  feet  into  the  bay,  and 
two  new  islands,  formed  of  ashes  and  stones  falling  from  the  volcano,  rose 
in  the  midst  of  the  water  several  miles  away.  Beyond  the  districts  close 
round  the  crater,  the  bed  of  dust,  which  fell  gradually,  became  thinnei-, 
but  it  was  carried  by  the  wind  more  than  40  degrees  of  longitude  toward 
the  west,  and  the  ships  sailing  in  those  waters  penetrated  with  difficulty 
the  layer  of  pumice-stone  spread  out  on  the  sea.  To  the  north,  the  rain 
*  Mittheilungen  von  Petermann,  vol.  vii.,  1863. 


ERUPTION  OP  COSEGUINA. 


471 


of  ashes  was  remarked  at  Truxillo,  Honduras,  and  at  Chiapas,  in  Mexico ; 
on  the  south,  it  reached  Carthageua,  Santa  Martha,  and  other  towns  of  the 
coast  of  Grenada ;  to  the  east,  being  carried  by  the  counter-current  of  the 
trade- winds,  it  fell  on  the  plains  of  St.  Ann's,  in  Jamaica,  at  a  distance  of 
800  miles.  The  area  of  land  and  water  on  which  the  dust  descended  must 
be  estimated  at  1,500,000  square  miles,  and  the  mass  of  matter  vomited 
out  could  not  be  less  than  65,500  million  cubic  yards. 


Fig.  197.  Eruption  of  Cosegnina. 


The  uproar  of  the  breaking  up  of  the  mountain  was  heard  as  far  as  the 
high  plateaux  of  Bogota,  situated  1025  miles  away  in  a  straight  line. 
While  the  formidable  cloud  was  settling  down  round  the  volcano,  thick 
darkness  filled  the  air.  For  forty-three  hours  nothing  could  be  seen  ex- 
cept by  the  sinister  light  of  the  flashes  darting  from  the  columns  of  steam, 
and  the  red  glare  of  the  vent-holes  opening  in  the  mountain.  To  escape 
from  this  prolonged  fight,  the  rain  of  ashes,  and  the  burning  atmosphere, 
the  inhabitants  who  dwelt  at  the  foot  of  Coseguina  fled  in  all  haste  along 
a  road  running  by  the  black  water  of  the  Bay  ofFonseca.  Men,  women, 
children,  and  domestic  animals  traveled  painfully  along  a  difficult  path, 
through  quagmires  and  marshes.  So  great,  it  is  said,  was  the  terror  of  all 
animated  beings  during  this  long  night  of  horror,  that  the  animals  them- 


472 


THE  EARTH. 


selves,  such  as  monkeys,  serpents,  and  birds,  joined  the  band  of  fugitives, 
as  if  they  recognized  in  man  a  being  endowed  with  intelligence  superior 
to  their  own,* 

A  large  number  of  volcanoes  have  diminished  in  height,  or  have,  indeed, 
entirely  disappeai-ed,  in  consequence  of  explosions,  which  reduced  their 
rocks  to  powder,  and  distributed  them  in  thick  sheets  on  the  ground  ad- 
jacent. Mount  Baker,  in  California,  and  the  Japanese  volcano  ofUnsen, 
have  thus  raised  the  level  of  the  surrounding  plains  at  the  expense  of  a 
diminution  in  their  own  volume.  In  1638,  the  summit  of  the  peak  of  Ti- 
mor, which  might  be  seen  like  a  light-house  from  a  distance  of  270  miles, 
exploded,  and  blew  up  into  the  air,  and  the  water  collecting,  formed  a  lake 
in  the  enormous  void  caused  by  the  explosion.     In  1815,  Timboro,  a  vol- 


Fig.  193.  Eruption  of  Timboro. 

cano  in  the  island  of  Sumbara,  destroyed  more  men  than  the  artillery  of 
both  the  armies  engaged  on  the  battle-field  of  Waterloo.  In  the  island 
of  Sumatra,  550  miles  to  the  west,  the  terrible  explosion  was  heard,  and, 
for  a  radius  of  300  miles  round  the  mountain,  a  thick  cloud  of  ashes, 
which  obscured  the  sun,  made  it  dark  like  night  even  at  noonday.  This 
immense  quantity  oi  debris,lhQ  whole  mass  of  which  was,  it  is  said,  eqniv- 
♦  Ij&ndigvebQ,  Naturgesrhichte  derVvlkane. 


FLAMES  FROM  VOLCANOES.  473 

aleut  to  thrice  the  bulk  of  Mont  Blanc— that  is,  2,358,000  millions  of  cubic 
yards  (?) — fell  over  an  area  larger  than  that  of  Germany.  The  pumice- 
stone  which  floated  in  the  sea  was  more  than  a  yard  in  thickness,  and  it 
was  with  some  difliculty  that  ships  could  make  their  way  through  it.  The 
j)opular  imagination  was  so  deeply  impressed  by  this  cataclysm,  that  at 
IJruni,  in  the  island  of  Borneo,  Avhither  heaps  of  the  dust  vomited  out  by 
Timboro,  870  miles  away  to  the  south,  had  been  carried  by  the  wind,  they 
date  their  years  from  "  the  great  fall  of  ashes."  It  is  the  commencement 
of  an  era  for  the  inhabitants  of  Bruni,just  as  the  flight  of  Mohammed  was 
for  the  Mussulmans. 

The  friction  of  the  steam  against  the  innumerable  particles  of  solid  mat- 
ter which  are  darted  out  into  the  air  is  the  principal  cause  of  the  electrici- 
ty which  is  developed  so  plentifully  during  most  volcanic  eruptions.  In 
consequence  of  this  friction,  which  operates  simultaneously  at  all  points 
in  the  atmosphere  which  are  reached  by  the  volcanic  ashes  and  vapor, 
sparks  flash  out  which  are  developed  into  lightning.  The  skies  are  light- 
ed up  not  only  by  the  reflection  from  the  lava,  but  also  by  coruscations  of 
light  which  dart  from  amid  the  clouds.  When  the  vast  canopy  of  vapor 
spreads  over  the  summit  of  the  mountains,  numerous  spirals  of  fire  whirl 
round  on  each  side  of  the  clouds,  which,  as  they  unroll,  resemble  the  foli- 
age of  a  gigantic  tree.  Doubtless,  also,  the  encounter  of  two  aerial  cur- 
rents may  contribute  to  produce  lightning  in<he  columns  of  vapor;  yet, 
when  the  latter  are  slightly  mingled  with  ashes,  they  are  rarely  stormy.* 

Although  the  evolution  of  electricity  in  the  columns  of  vapor  and  ashes 
vomited  out  by  volcanoes  has  never  been  called  in  question,  the  appear- 
ance of  actual  flames  at  the  time  of  volcanic  eruptions  was  for  a  long  time 
disputed.  M.  Sartorius  von  Waltershausen,  the  patient  observer  of  Etna, 
has  maintained  that  neither  this  mountain,  nor  Stromboli,  nor  any  other 
volcano,  has  ever  presented  among  its  phenomena  any  fire  properly  so 
called,  and  that  the  supposed  flames  were  nothing  more  than  the  reflec- 
tion of  the  red  or  white  lava  that  was  boiling  in  the  crater.  On  the  other 
hand,  Elie  de  Beaumont,  Abich,  and  Pilla  positively  assert  that  they  have 
seen  light  flames  on  the  summit  of  Vesuvius  and  Etna.  It  would,  however, 
be  very  natural  to  believe  that  inflammable  gases  might  be  liberated  and 
take  fire  at  the^utlet  of  those  immense  shafts  which  place  the  great  sub- 
terranean laboratory  of  lava  in  communication  with  the  outer  air. 

This  question  was,  however,  resolved  in  the  affirmative  at  the  time  of 
the  recent  eruption  of  Santorin,  and  popular  opinion  was  right  in  opposi- 
tion to  most  men  of  science.  All  those  who  were  able  to  witness,  at  its 
commencement,  the  upheaval  of  the  lava  at  Cape  Georges  and  Aphroessa, 
have  certified  to  the  appearance  of  burning  gas  dancing  above  the  lava, 
and  even  on  the  surface  of  the  sea.  All  round  the  upheaved  hillocks, 
bubbles  of  gas,  breaking  forth  from  the  waves,  became  kindled  as  they 
came  in  contact  with  the  burning  mass,  and  were  diff*used  over  the  water 
in  long  trains  of  white,  red,  or  greenish  flames,  which  the  breeze  alter- 
*  Arngo,  (Kuvres  Com/>/etes,  vol.  i. 


474  ^^^  EARTH. 

nately  raised  oi-  beat  down ;  sometimes  a  smart  puff  of  wind  put  out  the 
fire,  but  it  soon  recommenced  to  run  over  the  breakers :  by  approaching 
it  carefully,  fragments  of  paper  might  be  burnt  in  it,  which  lighted  as  they 
dropped.  On  the  slopes  of  the  volcano  of  Aphroessa,  fire,  rendered  of  a 
yellowish  hue  by  salts  of  soda,  sprung  out  from  all  the  fissures,  and  rose 
to  a  height  of  several  yards.  On  the  rather  older  lava  of  Cape  Georges 
the  trains  of  flame  were  less  numerous ;  ^here,  however,  bluish  glimmers 
might  be  seen  flitting  about  in  some  spots  over  the  black  ridges  of  lava.* 
Added  to  this,  are  not  the  flames  at  Bakou,  on  the  coast  of  the  Caspian 
Sea,  produced  by  the  volcanic  action  of  the  ground?  The  "growing 
mountains"  in  the  neighborhood  are  mud-volcanoes,  and  we  must  doubt- 
less attribute  to  the  same  subterranean  activity  the  production  of  the  hy- 
drogen gas  which  burns  in  an  "  eternal  flame"  in  the  temples  of  the  Parsi.f 
During  some  of  the  evenings  in  autumn,  when  the  weather  is  fine  and  the 
sun  has  heated  the  surface  of  the  ground,  the  flames  occasionally  make 
their  appearance  on  the  hills,  and  for  several  hours  may  be  seen  the  mar- 
velous spectacle  of  a  train  of  fire  stretching  along  the  country  without 
burning  the  ground,  and  even  without  scorching  a  blade  of  grass. 

*  Fouque,  Revue  des  Deux-Mondes,  August  If),  1866  ;•  Dekigallas ;  Schmidt, 
t  Arnold  Boscowitz,  Volcans  et  Tremblements  de  Terre. 


ERUPTIONS  OF  MUD.  475 


CHAPTER  LXIX. 

STREAMS    OF   MUD   EJECTED   BY   CRATERS. — MUD-VOLCANOES. 

Next  to  lava  and  ashes,  streams  of  water  and  mud  are  the  most  con- 
siderable products  of  volcanic  activity,  and  the  catastrophes  which  they 
have  caused  are  perhaps  among  the  most  terrible  which  history  has  to  re- 
late. By  means  of  these  sudden  deluges,  towns  have  been  swept  avuay  or 
swallowed  up,  whole  districts  dotted  over  with  habitations  have  been 
flooded  with  mud  or  converted  into  marshes,  and  the  entire  face  of  na- 
ture has  been  changed  in  the  space  of  a  few  hours. 

The  liquid  masses  which  descend  rapidly  from  the  mountain  height  do 
not  al\^ys  proceed  from  the  volcano  itself.  Thus  the  local  deluge  may 
be  caused  by  a  rapid  condensation  of  large  quantities  of  steam  which  es- 
cape from  the  crater  and  fall  in  torrents  on  the  slopes.  A  phenomenon  of 
this  kind  must  evidently  take  place  in  a  great  many  cases,  and  it  was 
doubtless  by  a  cataclysm  of  this  kind  that  the  town  of  Herculaneum,  at 
the  foot  of  Vesuvius,  was  buried.  As  regards  the  lofty  snow-clad  volca- 
noes of  the  tropical  and  temperate  zones,  and  also  those  of  the  frozen  re- 
gions, the  torrents  of  water  and  debris — the  "  water-lava,"  as  the  Sicilians 
call  them — may  be  explained  by  the. rapid  melting  of  immense  masses  of 
snow  and  ice,  with  which  the  burning  liava,  the  hot  ashes,  or  the  gaseous  ^ 
emanations  of  the  volcanic  furnace  have  come  in  contact.  Thus,  in  Ice- 
land, after  each  eruption,  formidable  deluges,  carrying  with  them  ice,  sco- 
riae, and  rocks,  suddenly  rush  down  into  the  valleys,  sweeping  away  ev- 
ery thing  in  their  course.  These  liquid  avalanches  are  the  most  terrible 
phenomena  which  the  inhabitants  of  the  island  have  to  dread.  They  show  . 
three  headlands  formed  of  debris,  which  the  body  of  water  descending  from 
the  sides  of  Kutlugaya  in  1766  threw  out  far  into  the  sea,  in  a  depth  of 
246  feet  of  water.* 

Other  deluges  no  less  formidable  are  caused  by  the  rupture  of  the  walls 
which  pen  back  a  lake  in  the  cavity  of  a  former  crater,  or  by,  the  forma- 
tion of  a  fissure  which  affords  an  outlet  to  liquid  masses  contained  in  sub- 
terranean reservoirs.  It  would  be  too  difficult  to  explain  otherwise  the 
mud-eruptions  of  several  trachytic  volcanoes  of  the  Andes — Imbambaru, 
Cotopaxi,  and  Carahuarizo.  In  fact,  the  mud  {lodozales)  which  comes 
down  from  these  mountains  often  contains  a  large  quantity  of  organized 
beings,  aquatic  plants,  infusoria,  and  even  fish,  which  could  only  have 
lived  in  the  calm  waters  of  a  lake.  Of  this  kind  is  the  Pimelodes  cydo- 
pum,  a  little  fish  of  the  tribe  of  the  Siluridce,  which,  according  to  Hum- 
boldt, has  hitherto  been  found  nowhere  except  in  the  Andini  caverns  and 
♦  Olafsen  and  Tovelsen,  British  Quarterly  Review,  April,  18GI. 


47G 


THE  EARTU. 


Fig.  199.  Crater  of  Seie  Cidades. 


in  the  rivulets  of  the  plateau  of  Quito.  In  1691  the  volcano  oflmbam- 
bai'u  vomited  out,  in  combination  with  mud  and  snow,  so  large  a  quantity 
of  these  remains  of  organisms  that  the  air  was  contaminated  by  them, 
and  miasmatic  fevers  prevailed  in  all  the  country  round.  The  masses  of 
water  which  thus  rush  down  suddenly  into  the  plains  amount  sometimes 
to  millions,  or  even  thousands  of  millions  of  cubic  yards. 

Although,  in  some  cases,  these  eruptions  of  mud  and  water  may  bo 
looked  upon  as  accidental  phenomena,  they  must,  on  the  contrary,  as  re- 
gards many  volcanoes,  be  considered  as  the  result  of  the  normal  action  of 
the  subterranean  forces.  They  are,  then,  the  waters  of  the  sea  or  of  lakes 
which,  having  been  buried  in  the  earth,  again  make  their  appearance  on 
the  surface,  mingled  with  rocks  which  they  have  dissolved  or  reduced  to 
a  pasty  state.  A  remarkable  instance  of.these  liquid  eruptions  is  tliat 
presented  by  Papandayang,  one  of  the  most  active  volcanoes  in  Java.  In 
1792  this  mountain  burst,  the  summit  was  converted  into  dust  and  disap- 
peared, and  the  debris,  spreading  far  and  wide,  buried  forty  villages. 
Since  this  epoch  a  copious  rivulet  gushes  out  in  the  very  mouth  of  the 
crater,  at  a  height  of  7710  feet,  and  runs  down  into  the  plain,  leaping  over 
the  blocks  of  trachyte.  Round  the  spring,  pools  of  water  fill  all  the  clefts 
in  the  rocks,  and  boil  up  incessantly  under  the  action  of  the  hot  vapoi*s 
which  rise  in  bubbles;  here  and  there  are  funnel-shaped  cavities,  in  which 


ERUPTIONS  OF  WATER  AND  MUD.  477 

black  and  muddy  water  constantly  ascends  and  sinks  with  the  same  reg- 
ularity as  the  waves  of  the  sea ;  elsewhere,  muddy  masses  slowly  issuing 
from  small  craters  flow  in  circular  slopes  over  mounds  of  a  few  inches  or 
a  yard  in  height ;  lastly,  jets  of  steam  dart  out  of  all  the  fissures  with  a 
shrill  noise,  making  the  ground  tremble  with  the  shock.  All  these  vari- 
ous noises,  the  roaring  of  the  cascades,  the  explosion  of  the  gaseous  springs, 
the  hoarse  murmur  of  the  mud-volcanoes,  the  shrill  hissing  oithefumerolles., 
produce  an  indescribable  uproar,  which  is  audible  far  away  in  the  plains, 
which,  too,  has  given  to  the  volcano  its  name  of  Papandayang,  or  "Forge," 
as  if  one  could  incessantly  hear  the  mighty  blast  of  the  flames  and  the 
ever-recurring  beating  of  the  anvils. 

In  volcanoes  of  a  great  height  it  is  rarely  found  that  eruptions  of  water 
and  mud  are  constant,  as  in  the  Papandayang ;  but  temporary  ejections 
of  liquid  masses  are  frequent,  and  there  are,  indeed,  some  volcanoes  which 
vomit  out  nothing  but  muddy  matter.  The  volcano  of  Aqua  (or  tcater), 
the  cone  of  which  is  gently  inclined  like  that  of  Etna,  and  rises  to  about 
13,000  feet  in  height,  into  the  regions  of  snow,  has  never  vomited  any  thing 
but  water;  and  it  is,  indeed,  stated  that  lava  and  other  volcanic  products 
are  entirely  wanting  on  its  slopes.*  Yet  in  1541,  this  prodigious  inter- 
mittent spring  hurled  into  the  air  its  terminal  point  (coronilla),  and  poured 
over  the  plains  at  its  base,  and  over  the  town  of  Guatemala,  so  large  a 
quantity  of  water,  mingled  with  stones  and  debris^  that  the  inhabitants 
were  compelled  to  fly  with  the  greatest  haste,  and  to  reconstruct  their 
capital  at  the  foot  of  the  volcano  of  Fuego.  This  new  neighbor,  however, 
showed  that  he  was  as  much  or  more  to  be  dreaded  than  their  former  one, 
for  the  violent  eruptions  from  the  mountain  compelled  the  inhabitants  of 
the  second  town  to  again  migrate,  and  to  rebuild  their  capital  at  a  point 
20  miles  to  the  northwest. 

Several  volcanoes  in  Java  and  the  Philippines  also  give  vent,  duying 
their  eruptions,  to  large  quantities  of  mud,  sometimes  mingled  with  or- 
ganic matter  in  such  considerable  proportions  that  they  have  been  utilized 
as  fuel.f  In  1793,  a  few  months  after  the  terrible  eruption  of  Unsen,  in 
the  island  of  Kiousiou,|  an  adjacent  volcano,  the  Miyi-Yama,  vomited,  ac- 
cording to  Kampfer,  so  prodigious  a  quantity  of  water  and  mud  that  all 
the  neighboring  plains  were  inundated,  and  53,000  people  were  drowned 
in  the  deluge ;  unfortunately,  we  have  no  historical  details  of  this  catas- 
trophe. Of  all  the  eruptions  of  mud,  the  best  known  is  that  of  Tungura- 
gua,  a  volcano  in  Ecuador,  which  rises  to  the  south  of  Quito  to  16,400 
feet  in  height.  In  1797,  at  the  time  of  the  earthquake  of  Riobamba,  a 
whole  side  of  the  mountain  sank  in  an  immense  downfall,  with  the  forests 
which  grew  on  it;  at  the  samre  time,  a  flow  of  viscous  mud  issued  from  the 
fissures  at  its  base,  and  rushed  down  into  the  valleys.  One  of  these  cur- 
rents of  mud  filled  up  a  winding  defile,  which  separated  two  mountains, 
to  a  depth  of  650  feet,  over  a  width  of  more  than  1000  feet,  and,  damming 

*  Juarros,  Landgrebe,  Natur  Gesrhirhte  der  Vulkane,  vol.  i. 

t  Otto  V'olger,  Das  Buck  der  Erde^  vol.  i.  J  Vide  above,  p.  4.')2. 


478  ^^E  EARTH. 

up  the  rivulets  at  their  outlet  from  the  side  valleys,  kept  back  the  water 
in  temporary  lakes:  one  of  these  sheets  of  water  remained  for  eighty-seven 
days. 

The  volcanic  mud,  therefore,  has  this  point  of  resemblance  with  the  lava 
— that  it  sometimes  flows  out  through  the  crater,  as  on  Papandayang ; 
sometimes  through  side  craters,  as  on  Tunguragua.  Doubtless,  when  the 
volcanic  muds  have  been  better  studied,  we  shall  be  enabled  to  trace  the 
transition  which  takes  place  by  almost  imperceptible  degrees  between  the 
more  or  less  impure  water  escaping  from  volcanoes,  and  the  burning  lava 
more  or  less  charged  with  steam.  This  transition  is,  however,  already 
noticed  in  the  ancient  matter  which  the  water  has  carried  down  and  de- 
posited in  the  strata  at  the  foot  of  volcanic  mountains.  These  rocks, 
known  under  the  name  o^tufa^  trass,  or  perperino,  are  nothing  but  heaps 
of  pumice,  scoriae,  ashes,  and  mud,  cemented  together  by  the  water  into  a 
species  of  mortar  or  conglomerate,  and  gradually  solidified  by  the  evapo- 
ration of  the  humidity  which  they  contained.  Of  this  kind,  for  instance,  is 
the  hardened  stone  which,  for  eighteen  centuries,  has  covered  the  city  of 
Herculaneum  with  a  layer  of  50  to  150  feet  in  thickness.  Among  rocks 
of  various  fonnations,  there  are  but  few  which  exhibit  a  more  astonishing 
diversity  than  the  tufas.  They  differ  entirely  in  appearance  and  physical 
qualities,  according  to  the  nature  of  the  materials  which  have  formed 
them,  the  quantity  of  water  which  has  cemented  them,  the  greater  or  less 
rapidity  with  which  their  fall  and  desiccation  take  place ;  lastly,  the  num- 
ber and  distribution  of  the  chinks  which  are  produced  across  the  dried 
mass,  and  have  been  filled  up  with  the  most  different  substances.  Many 
kinds  of  tufa  resemble  the  most  beautiful  marble. 

The  small  hillocks,  which  are  specially  called  mud-volcanoes,  or  salses, 
on  account  of  the  salts  which  are  frequently  deposited  by  their  waters, 
are  cones  which  differ  only  in  their  dimensions  from  the  mighty  volcanoes 
of  Java  or  the  Andes.  Like  these  great  mountains,  they  shake  the  ground, 
and  rend  it, in  order  to  discharge  their  pent-up  matter;  they  emit  gas  and 
steam  in  abundance,  add  to  their  slopes  by  their  own  debris,  shift  their 
placres,  change  their  craters,  throw  off  their  summits  in  their  explosions ; 
lastly,  some  of  these  salses  are  incessantly  at  work,  while  others  have  pe- 
riods of  repose  and  activity.  In  nature,  transitions  merge  into  one  another 
so  perfectly,  that  it  is  difiicult  to  discover  any  essential  difference  between 
a  volcano  and  a  salse,  and  between  the  latter  and  a  thermal  spring.* 

Mud-volcanoes  exist  in  considerable  numbers  on  the  surface  of  the  earth, 
and,  like  the  volcanoes  of  lava,  the  neighborhood  of  the  sea-coast  is  the 
principal  locality  where  we  find  their  little  cones.  In  Europe,  the  most  re- 
markable are  those  which  are  situated  at  the  two  extremities  of  the  Cau- 
casus, on  the  coasts  of  the  Caspian  Sea,  and  on  both  sides  of  the  Straits  of 
Yenikale,  which  connect  the  Sea  of  Azof  with  the  Black  Sea.  On  the  east, 
the  mud-springs  of  Bakou  are  especially  distinguished  by  their  combina- 
tion with  inflammable  gases;  on  the  west,  those  of  Taman  and  Kertch  flow 

*  Humboldt,  Cosmos,  vol.  i. 


MUD-VOLCANOES.  479 

all  the  year  round,  but  especially  during  times  of  drought,  pouring  out 
large  quantities  of  blackish  mud.  One  of  these  mud-volcanoes,  the  Go- 
rela,  or  Kuku-Oba,  which,  in  the  time  of  Pallas,  was  called  the  "Hell,"  or 
Prekla,  on  account  of  its  frequent  eruptions,  is  no  less  than  246  feet  in 
height,  and  from  this  crater,  which  is  perfectly  distinct,  muddy  streams 
have  flowed,  one  of  which  was  2624  feet  long,  and  contained  about  850,000 
cubic  yards.* 

The  volcanitos  of  Turbaco,  described  by  Humboldt,  and  the  maccalube 
of  Girgenti,  which  have  been  explored,  since  Dolomieu,  by  most  European 
savants  who  have  devoted  themselves  to  the  study  of  subterranean  forces, 
are  also  well-known  examples  of  mud-springs,  and  may  serve  as  a  type  to 
all  the  hillocks  of  the  same  character.  In  winter,  after  a  long  coui-se  of 
rains,  the  plain  of  the  maccalube  is  a  surface  of  mud  and  water  forming  a 
kind  of  boiling  paste,  from  which  steam  makes  its  escape  with  a  whistling 
noise ;  but  the  warmth  of  spring  and  sumAer  hardens  this  clay  into  a 
thick  crust,  which  the  steam  breaks  through  at  various  points  and  covers 
with  increasing  hillocks.  At  the  apex  of  these  cones  a  bubble  of  gas 
swells  up  the  mu^  like  a  blister,  and  then  bursts  it,  the  semi-liquid  flowing 
in  a  thin  coat  over  the  mound;  then  a  fresh  bubble  ejects  more  mud,  which 
spreads  over  the  first  layer  already  become  hard,  and  this  action  continues 
incessantly  until  the  rains  of  winter  again  wash  away  all  the  cones.  This 
is  the  ordinary  course  of  action  of  the  salse,  sometimes  interrupted  by  vi- 
olent eruptions.!  On  the  coasts  of  Mekran  the  mud-volcanoes  are  not  only 
subject  to  the  action  of  the  seasons,  but  also  depend  on  the  action  of  the 
tides,  although  many  of  them  are  from  9  to  12  miles  from  the  Indian 
Ocean.  At  the  time  of  the  flow  the  mud  rises  in  great  bubbles,  accompa- 
nied by  a  hoarse  murmur,  like  the  distant  roar  of  thunder.  The  highest 
cone  is  not  more  than  246  feet  high,  and  stands  7  miles  from  the  shore.J 

In  a  general  way,  the  expulsion  of  mud  and  gas  is  accompanied  by  a 
discharge  of  heat ;  but  in  some  salses,  like  those  of  Mekran,  the  matter 
ejected  is  not  higher  in  temperature  than  the  surrounding  air,  as  if  the 
expulsion  of  the  mud  from  the  ground  was  an  entirely  superficial  phe- 
nomenon. Occasionally,  in  peat-bogs,  the  gi'ound  cracks,  and  cold  mud  is 
ejected  from  the  fissure;  and  then,  after  this  kind  of  eruption,  the  spongy 
soil  sinks  and  again  levels  down.  Is  this  eruptive  phenomenon  similar  to 
that  presented  by  the  mud-volcanoes,  and  caused  by  the  fennentation  of 
gases  in  the  midst  of  substances  in  a  state  of  putrefaction  ?  This  is  M. 
Otto  Volger's  idea;  and  it  would  be  difiicult  to  give  any  other  explana- 
tion of  this  phenomenon. 

*  Ansted,  Intellectual  Observer,  January,  1866. 

t  Arnold  Boscowitz,  Volcam  et  Tremblements  de  Terre. 

X  Walton,  Nautical  Magazine,  February,  1863. 


480 


TUE  EARTH. 


CHAPTER  LXX. 

VOLCANIC     THERMAL     SPRINGS. GEYSERS. SPRINGS     IN     NEW    ZEALAND. 

FUMEROLLES. — SOLFATARAS. — CRATERS   OF   CARBONIC   ACID. 

Volcanoes,  both  of  lava  and  inud,  all  have,  either  on  their  sides  or  in 
the  vicinity  of  their  base,  thermal  springs,  which  afford  an  outlet  to  their 
surplus  water,  gas,  and  vapor.  Most  even  of  those  mountains  which  are 
at  present  tranquil,  but  Avhich  were  once  centres  of  eruption,  continue  to 
manifest  their  activity  by  vapors  and  gas,  like  furnaces  in  which  the  flames 
are  extinct,  but  the  smoke  ^s  still  rising.  Although  lava  and  ashes  no 
longer  make  their  escape  from  the  crater  or  lateral  fissures,  yet  numerous 
fumeroUes  and  hot  springs,  formed  by  the  condensation  of  the  steam,  gen- 
erally serve  as  a  vehicle  for  the  gas  pent  up  in  the  depths  of  the  moun- 
tain. We  may  reckon  by  hundreds  and  thousands  the  "geysers,"  the 
"  vinegar  springs,"  and  other  thermal  springs  in  countries  once  burning 
with  volcanoes,  the  fires  of  which  are  extinct,  or  at  least  quieted  down  for 
a  period  more  or  less  protracted.  Thus  the  form^*  volcanoes  of  Auvergne ; 
the  mountains  of  the  Eifel,  on  the  Rhine,  the  craters  of  which  contain 
nothing  but  lakes  or  pools ;  the  Demavend,  with  its  mouth  filled  up  with 


Fig.  aw.  (Jraier  of  Demavend. 


snow — all  Still  exhale  here  and  there,  through  springs  smd  fumeroUes,  as  it 
were,  a  feeble  breath  of  their  once  mighty  vitality. 

The  volcanic  regions  of  the  earth  where  thermal  springs  gush  out  are 
very  numerous :  in  Europe  we  have  Sicily,  Iceland,  Tuscany,  and  the  pen- 


THERMAL  SPRINGS.  ,  481 

insula  of  Kertch ;  in  America — that  land  so  rich  in  volcanoes — the  springs 
warmed  by  subterranean  vapor  are  still  more  numerous,  and  there  are 
some  on  the  sides  of  the  volcano  Nuevo  de  Chilian  which  gush  out  through 
a  thick  bed  of  perpetual  snow.*  A  lateral  gorge  of  the  valley  of  Napa, 
in  California,  called  the  "  Devil's  Canon,"  may  be  quoted  as  one  of  the 
most  striking  examples  of  the  active  production  of  thermal  waters.  The 
narrow  ravine,  filled  with  vapor  rising  in  eddies,  opens  on  the  side  of  a  red 
and  bare  mountain,  that  one  might  fancy  was  scorched  by  fire.  The  entry 
to  the  ravine  follows  the  course  of  a  rivulet,  the  boiling  waters  of  which 
are  mingled  with  chemical  substances  horrible  to  the  taste.  Innumerable 
springs — some  sulphurous,  others  charged  with  alum  or  salt — gush  out  at 
the  base  of  the  rocks.  There  are  both  warm  and  cold  springs,  and  hot 
and  boiling ;  some  are  blue  and  transparent,  others  white,  yellow,  or  red 
with  ochre.  In  a  cavity  which  is  called  the  "  Sorcerers'  Caldron"  a  mass 
of  black  and  fetid  mud  boils  up  in  great  bubbles.  Higher  up,  the  "  Devil's 
Steam-boat"  darts  out  jets  of  gaseous  matter,  which  issue  puffing  from  a 
wall  of  rock :  fumeroUes  may  be  seen  by  hundreds  on  the  sides  of  the 
mountain.  All  these  various  agents  either  murmur,  whistle,  rumble,  or 
roar,  and  thus  a  tempest  of  deafening  sounds  incessantly  fills  the  gorge. 
The  burning  ground,  composed  of  a  clayey  mud — in  one  spot  yellow  with 
sulphur,  and  in  another  white  with  chalk — gives  way  under  the  feet  of 
the  traveler  who  ventures  on  it,  and  gives  vent  to  puflfs  of  vapor  through 
its  numberless  cracks.  The  whole  gorge  appears  to  be  the  common  out- 
let of  numerous  reservoirs  of  various  mineral  waters,  all  heated  by  some 
great  volcanic  furnace.f 

The  ravine  of  Infernillo  (Little  Hell),  which  is  situated  at  the  base  of 
the  volcano  of  San  Vincente,  in  the  centre  of  the  Republic  of  San  Salvador, 
presents  phenomena  similar  to  those  of  the  "  Devil's  Canon."  Thei*e,  too, 
a  multitude  of  streams  of  boiling  water  gush  from  the  soil,  which  is  cal- 
cined like  a  brick,  and  eddies  of  vapor  spring  from  the  fissures  of  the  rock 
with  a  noise  like  the  shrill  whistle  of  a  locomotive.  The  most  considera- 
ble body  of  water  issues  from  a  fissure  32  feet  in  width,  which  opens  un- 
der a  bed  of  volcanic  rocks  at  a  slight  elevation  above  the  bottom  of  the 
valley.  The  liquid  stream,  partially  hidden  by  the  clouds  of  v-apor  which 
rise  from  it,  is  shut  out  to  a  distance  of  130  feet  as  if  by  a  force-pump,  and 
the  whistling  of  the  water  pent  up  between  the  rocks  reminds  one  of  the 
furnace  of  a  manufactory  at  full  work.  One  might  fancy  that  it  was  the 
respiration  of  some  prodigious  being  hidden  under  the  mountain. 

The  hottest  springs  which  gush  out  on  the  surface  of  the  ground,  such 
as  those  of  Las  Trincheras  and  Comangillas,  do  not  reach  the  temperature 
of  212°  (Fahr.);J  but  we  have  no  right  to  conclude  from  this  that  the 
water  in  the  interior  of  the  earth  does  not  rise  to  a  much  more  considera- 
ble heat.     It  is,  on  the  contrary,  certain  that  water  descending  into  the 

*  Philippi,  3fi7<Aet7un^en  von  Petermann,  voL  vii.,  1863. 

t  Henry  Auchincloss,  Continental  Monthly,  September,  1864. 

X  Vide  above,  p.  235. 

Hh 


4g2  ^^^  EARTH. 

deepest  fissures  of  the  earth,  although  still  maintaining  a  liquid  state,  may 
reach,  independently  of  any  volcanic  action,  a  temperature  of  several  hun- 
dred degrees;  being  compressed  by  the  liquid  masses  above  it,  it  is  not 
converted  into  steam.  At  a  depth  which  is  not  certainly  known,  but 
which  various  savants  have  approximately  fixed  at  49,000  feet,  water  of  a 
temperature  exceeding  750°  (Fahr.)  ultimately  attains  elasticity  sufficient 
to  overcome  the  formidable  weight  of  1500  atmospheres  which  presses  on 
it ;  it  changes  into  steam,  and  in  this  new  form  mounts  to  the  surface  of 
the  earth  through  the  fissures  of  the  rocks.*  Even  if  this  steam,  passing 
through  beds  of  a  gradually  decreasing  temperature,  is  again  condensed 
and  runs  back  again  in  the  form  of  water,  still  it  heats  the  liquid  whicli 
surrounds  it,  and  increases  its  elasticity ;  it  consequently  assists  the  gen- 
eration of  fresh  jets  of  steam,  which  likewise  rise  toward  the  upper  re- 
gions. Thus,  step  by  step,  water  is  converted  into  steam  up  to  the  very 
surface  of  the  earth,  and  springs  out  from  fissures  in  the  shape  oi  fume- 
roUes. 

In  Iceland,  California,  New  Zealand,  and  several  other  volcanic  regions 
of  the  world,  jets  of  steam  mingled  with  boiling  water  are  so  considerable 
as  to  rank  among  the  most  astonishing  phenomena  of  the  planet.  The 
most  celebrated,  and  certainly  the  most  beautiful,  of  all  these  springs  is  the 
Great  Geyser  of  Iceland.  Seen  from  afar,  light  vapors,  creeping  over  the 
low  plain  at  the  foot  of  the  mountain  of  Blafell,  point  out  the  situation  of 
the  jet  of  water  and  of  the  neighboring  springs.  The  basin  of  siliceous 
stone  which  the  Geyser  itself  has  formed  during  the  lapse  of  centuries  is 
no  less  than  52  feet  in  width,  and  serves  as  the  outer  inclosure  of  a  fun- 
nel-shaped cavity,  75  feet  deep,  from  the  bottom  of  which  rise  the  water 
and  steam.  A  thin  liquid  sheet  flows  over  the  edges  of  the  basin,  and  de- 
scends in  little  cascades  over  the  outer  slope.  The  cold  air  lowers  the 
temperature  of  the  water  on  the  surface,  but  the  heat  increases  more  and 
more  in  all  the  layers  beneath ;  every  here  and  there  bubbles  are  formed 
at  the  bottom  of  the  water,  and  burst  when  they  emerge  into  the  air. 
Soon  bodies  of  steam  rise  in  clouds  in  the  green  and  transparent  water, 
but,  meeting  the  colder  masses  on  the  surface,  they  again  condense.  Ulti- 
mately they  make  their  way  into  the  basin,  and  cause  the  water  to  bubble 
up ;  steam  rises  in  different  places  from  the  liquid  sheet,  and  the  tempera- 
ture of  the  whole  basin  reaches  the  boiling-point ;  the  surface  swells  up  in 
foamy  heaps,  and  the  ground  trembles  and  roars  with  a  stifled  sound. 
The  caldron  constantly  gives  vent  to  clouds  of  vapor,  which  sometimes 
gather  round  the  basin,  and  sometimes  are  cleared  away  by  the  wind.  At 
intervals,  a  few  momeitts  of  silence  succeed  to  the  noise  of  the  steam. 
Suddenly  the  resistance  is  overcome,  the  enormous  jet  leaps  out  with  a 
crash,  and,  like  a  pillar  of  glittering  marble,  shoots  up  more  than  100  feet 
in  the  air.  A  second  and  then  a  third  jet  rapidly  follow ;  but  the  mag- 
nificent spectacle  lasts  but  for  a' few  minutes.  The  steam  blows  away; 
the  water,  now  cooled,  falls  in  and  round  the  basin ;  and  for  hours,  or  even 

*  Vide  above,  p.  436. 


THERMAL  SPRINGS.  483 

days,  a  fresh  eruption  may  be  waited  for  in  vain.  Leaning  over  the  edge 
of  the  hole  whence  such  a  storm  of  foam  and  water  has  just  issued,  and 
looking  at  the  blue,  transparent,  and  scarcely-rippled  surface,  one  can 
hardly  believe,  says  Bunsen,  in  the  sudden  change  which,  has  taken  place. 

The  slight  deposits  of  siliceous  matter  which  are  left  by  the  evaporation 
of  the  boiling  water  have  already  formed  a  conical  hillock  round  the 
spring,  and,  sooner  or  later,  the  increasing  curb  of  stone  will  have  so  con- 
siderably augmented  the  pressure  of  the  liquid  mass  in  the  spring  that  the 
waters  must  ultimately  open  a  fresh  outlet  beyond  the  present  cone. 
From  the  experiments  and  observations  made  by  Forbes  as  to  the  forma- 
tion of  the  layer  of  incrustations  round  the  jet,  this  spring  must  have  com- 
menced its  eruptions  ten  centuries  and  a  half  ago,  and  they  will  pi'obably 
cease  in  a  much  shorter  space  of  time.  Not  far  from  the  Geyser,  the 
mound  of  deposits  from  which  is  not  less  than  39  feet  in  height,  there  are 
a  number  of  pools  which  once  acted  as  basins  for  springs  which  gushed 
up  through  them,  but  are  now  nothing  but  cisterns  filled  with  blue  and 
limpid  water,  at  the  bottom  of  which  may  be  seen  the  month  of  a  former 
channel  of  eruption.  A  shifting  in  the  position  of  the  centre  of  activity 
takes  place  in  the  Geyser,  just  as  in  mud- volcanoes  and  incrusting  springs. 
Several  springs  lying  on  the  same  terrestrial  fissure  as  the  gveaXjet  d^eau, 
the  Strokkr,  the  Small  Geyser,  and  some  others,  present  phenomena  which 
are  nearly  similar,  and  are  evidently  subject  to  the  action  of  the  same 
forces.  The  vicinity  of  the  active  volcanoes  of  Iceland  warrants  us,  how- 
ever, in  supposing  that  the  water  produced  by  the  melting  of  the  snow  on 
Blafell  does  not  require  to  descend  many  thousands  of  yards  into  the  earth 
in  order  to  be  converted  into  steam.  There  is  no  doubt  that,  at  no  very 
great  depth  below  the  surface,  they  come  in  contact  with  burning  lava, 
which  gives  them  their  high  temperature.  By  reproducing  in  miniature 
all  the  conditions  which  are  thought  to  apply  to  the  Icelandic  springs — 
that  is,  by  heating  the  bases  of  tubes  of  iron  filled  with  water  and  sur- 
mounted by  a  basin — Tyndall  succeeded  in  producing  in  his  laboratory 
charming  little  geysers,  which  jetted  out-every  five  minutes. 

About  the  centre  of  the  northern  island  of  New  Zealand  the  activity  of 
the  volcanic  springs  is  manifested  still  more  remarkably  even  than  in  Ice- 
land. On  the  slightly-winding  line  of  fissure  which  extends  from  the 
southwest  to  the  northeast,  between  the  ever-active  volcano  of  Tongariro 
and  the  smoking  island  of  Whakari,  in  Plenty  Bay,  thermal  springs,  mud- 
fountains,  and  geysers  rise  in  more  than  a  thousand  places,  and  in  some 
spots  combine  to  form  considerable  lakes.  In  some  localities  the  hot  va- 
pors make  their  escape  from  the  sides  of  the  mountains  in  such  abundance 
that  the  soil  is  reduced  to  a  soft  state  over  vast  surfaces,  and  flows  down 
slowly  to  the  plains  in  long  beds  of  mud.  For  a  distance  of  more  than  a 
mile  a  portion  of  the  Lake  of  Taupo  boils  and  smokes  as  if  it  was  heated 
by  a  subterranean  fire,  and  the  tempera'ture  of  its  water  reaches  on  the 
average  to  100°  (Fahr.),  Farther  to  the  north,  the  two  sides  of  the  valley, 
through  which  flows  the  inipetuous  river  of  Waikato  after  its  issue  from 


484 


THi:  EARTH. 


the  Lake  Taupo,  present,  for  more  than  a  mile,  so  large  a  number  of  water- 
jets,  that  in  one  spot  as  many  as  seventy-six  are  counted.  These  geysers, 
which  rise  to  various  heights,  play  alternately,  as  if  obeying  a  kind  of 
rhythm  in  their  successive  appearances  and  disappearances.     While  one 


174.'E,c.f  Pirls 


J^^&i 


Fig.  201.  Volcanic  Region  of  New  Zealand. 

springs  out  of  the  ground,  falling  back  into  its  basin  m  a  graceful  curve 
bent  by  the  wind,  another  ceases  to  jet  out.  In  one  spot  a  whole  series 
oi  jets  cVeau  suddenly  become  quiet,  and  the  basins  of  still  water  emit 
nothing  but  a  thin  mist  of  vapor.     Farther  oo,  however,  the  mountain  is 


THES3IAL  SPRINGS,  ETC.,  OF  NEW  ZEALAND. 


485 


all  activity ;  liquid  columns  Sll  at  once  shine  in  the  sun,  and  white  cas- 
cades fall  from  terrace  to  terrace  toward  the  river.  Every  moment  the 
features  of  the  landscape  are  being  modified,  and  fresh  voices  take  a  part 
in  the  marvelous  concert  of  the  gushing  springs.* 

About  the  middle  of  the  interval  which  separates  the  Lake  of  Taupo 
from  the  coast  of  Plenty  Bay,  several  other  volcanic  pools  are  dotted 
about,  all  most  remarkable  for  their  thermal  and  jetting  springs.  One  of 
them,  however,  is  among  the  great  wonders  of  the  world.  This  is  the  Lake 
of  Rotomahana,  a  small  basin  of  about  120  acres,  the  temperature  of  which, 
being  raised  by  all  the  hot  springs  which  feed  it,  is  about  78°  (Fahr.).  Dr. 
von  Hochstetter  has  not  even  attempted  to  count  the  basins,  the  funnels, 
and  the  fissures  from  which  the  water,  steam-mud,  and  sulphurous  gases 
make  their  escape.  Here  and  there,  indeed,  he  noticed,  all  together,  salses^ 
solfataras,  fumerolles.,  and  springs.  The  most  magnificent  of  all  these  jets 
is  the  Tetarata,  about  82  feet  above  the  eastern  bank  of  the  lake.    The 


Fig.  202.  Section  across  the  terraced  Basius  of  Tetarata. 


basin,  from  the  centre  of  which  the  water  and  steam  spout  out,  is  a  kind 
of  crater,  286  feet  in  circumference,  which  is  surrounded  by  ramparts  of 
red  clay  32  feet  in  height,  resembling  the  sides  of  a  crater.  The  basin  is 
full  of  clear  water,  which  has  entirely  covered  the  former  with  a  coating 
of  silex,  white  as  marble.  The  water  in  this  dazzling  basin  assumes  a  de- 
licious blue  shade,  which  is  rendered  more  beautiful  by  the  reflection  of 
the  steam  unrolling  its  spiral  clouds.  The  liquid  which  flows  from  the 
basin  uins  into  another  pool,  likewise  covered  by  a  coating  of  silcx,  and, 
falling  from  terrace  to  terrace,  thus  reaches  the  level  of  the  lake.  These 
glittering  steps,  over  which  the  water  spreads  in  thin  sheets,  and  then  falls 
in  cascades,  form  a  wonderful  spectacle  of  splendor  and  grace.  Sometimes 
— say  the  natives — the  whole  body  of  liquid  in  the  upper  basin  is  sudden- 
ly upheaved  in  an  enormous  column,  and  the  pool  empties  30  feet  of  its 
depth ;  in  this  case  nothing  can  be  wanting  to  complete  the  grandeur  of 
the  picture. 

Have  these  wonderful  springs  existed  for  any  great  length  of  time,  and 
are  they  destined  to  be  preserved  for  centuries  in  all  their  beauty  ?  These 
are  points  as  yet  uhknown.  When  the  New  Zealand  springs  have  been 
studied  for  a  considerable  number  of  years,  it  will  perhaps  be  possible  to 
describe  the  various  modifications  which  are  taking  place  in  consequence 
*  F.  von  Hochstetter,  Neu-Seeland. 


486  THE  EARTH. 

of  the  increase  or  relaxation  of  the  subterranean  action  in  these  regions. 
In  several  parts  of  Europe  thermal  springs  have  gradually  lost  both  their 
heat  and  their  mineral  qualities,  owing  to  the  cooling  of  the  furnace  which 
heated  them,  and  are  becoming  more  and  more  similar  to  ordinary  springs : 
of  this  kind,  for  example,  are  the  springs  of  Bertrichbad,  in  Luxembourg.* 

The  gases  which  make  their  escape  from  the  fumerolks  situated  above 
hidden  beds  of  lava  do  not  differ  from  those  produced  by  great  volcanic 
eruptions ;  they  are  the  hydrochloric,  sulphuric,  and  carbonic  acids,  either 
in  a  state  of  purity  or  in  combination  with  alkaline,  earthy,  or  metallic 
bases,  and,  as  in  the  moving  currents  of  lava,  they  indicate  by  their  com- 
position the  degree  of  intensity  of  the  subterranean  heat.  The  most  pre- 
cise indications  on  these  points  have  been  furnished  by  the  analyses  of 
MJVI.  Bunsen,  Ch.  Sainte-Claire  Deville,  and  Fouque. 

When  they  issue  from  the  e2Lrt\x^fumerolles  deposit  on  the  edges  of  the 
fissure  various  substances,  such  as  sulphur,  alum,  and  borax,  which  have 
been  sublimated  in  the  subterranean  laboratory ;  the  vapors  then  spread 
out  into  wide  eddies,  and  are  lost  in  the  air.  There  is  no  spot  in  Europe 
where  ihe^e  fumerolles  can  be  better  studied  than  in  the  former  crater  of 
the  Isle  of  Volcano.  The  cavity,  at  the  bottom  of  which  all  these  chem- 
ical operations  take  place,  is  more  than  a  mile  in  circumference,  and  its 
southern  sides  rise  to  980  feet  in  height ;  the  bottom  of  the  abyss  may  be 
about  320  feet  wide.  Through  the  mist  of  vapor  which  fills  the  immense 
caldron  a  spectator  sees  the  lofty  cliffs,  red  or  golden  yellow  in  color,  and 
streaked  here  and  there  with  most  varied  hues.  On  the  slopes  leading  to 
the  bottom  of  the  gulf  the  crumbling  stones  give  way  under  the  tread, 
and  yet  it  is  necessary  to  descend  at  a  running  pace,  for  in  some  places 
the  hollow  soil  is  burning  like  an  arch  over  an  oven.  Vapor  creeps  along 
slowly  over  the  slopes.  The  air  is  saturated  with  hydrochloric  and  sul- 
phurous acid  gases,  and  is  difficult  to  breathe.  An  incessant  noise  of  dull 
sobbings  and  whistlings  fills  the  hollow,  and  on  every  side  there  are  small 
orifices  between  the  stones,  whence  jets  of  steam  spring  eddying  out. 
This  is  the  spot  whither  tte  workmen — who  seem  accustomed  to  Uve  in 
the  fire,  like  thetiegendary  salamanders — resort  to  gather  the  sta^ctites 
of  gilded  sulphur  which  still  ci'ackle  from  the  effect  of  heat,  and  the  fine 
needles  of  boracic  acid,  white  as  swan's-down.  At  night  the  masses  of 
vapor  accumulated  above  the  crater  are  colored  with  a  red  glare,  as  if 
from  the  reflection  of  an  immense  fire. 

Sometimes  the  rain  which  falls  into  the  amphitheatre  forms  there  a  tem- 
porary lake ;  but  a  great  part  of  the  water  makes  its  escape  through  the 
fissures  in  the  ground,  and  flows  in  a  stream  over  the  external  slopes,  the 
remainder  being  rapidly  evaporated  by  the  heat  of  the  mountain.  Some 
o^  the  fumerolles,  the  gases  of  which  were  analyzed  in  1865  by  M.  Fouque, 
attain  a  temperature  above  680°  (Fahr.).  Other  jefs  of  less  heat  make 
their  appearance  in  various  parts  of  the  island,  and  even  in  the  waters  of 
the  bay.  From  the  edges  of  the  great  crater  these  vapors  may  be  seen 
*  See  chapter  on  "Springs." 


ISLE  OF  VOLCANO. 


487 


at  the  base  of  the  slopes  rising  from  the  bed  of  the  sea,  and  developing 
into  wide,  whitish-colored  spirals,  similar  in  hue  to  the  mud  of  potters' 
clay.  In  certain  places  the  temperature  of  the  sea-water  heated  by  these 
gases  is  so  high  that  voyagers  can  afford  themselves  the  childish  satisfac- 
tion of  boiling  their  eggs  in  it. 


Fig.  203.  Island  of  Volcano. 


The  aolfatara  in  the  Islf  of  Volcano  produces  scarcely  10  tons  of  sul- 
phur every  year.  This  does  not  seem  much ;  but  if  we  were  to  calculate 
by  centuries  and  geological  periods  the  quantities  deposited  by  thefume- 
rolles,  it  would  seem  really  enormous.  Thus  the  mines  of  Sicily,  which 
have  been  worked  for  some  centuries,  furnish  every  year  to  commerce  no 


488  THE  EARTH. 

less  than  300,000  tons  of  sulphur,  and  yet  the  mining  operations  in  these 
districts  are  altogether  of  a  primitive  character.  A  large  number  of  beds 
are  unexplored,  and  nearly  a  third  of  the  sulphur  brought  to  the  surface 
evaporates  in  the  furnaces  or  is  lost  in  the  debris.  These  almost  inex- 
haustible veins  appear  to  have  been  all  produced,  like  the  deposits  of  the 
Isle  of  Volcano,  by  jets  of  vapor  saturated  with  sulphur. 

Sometimes  carbonic  acid  gas  is  the  only  gas  which'is  discharged  from 
the  caverns  and  craters  of  volcanoes.  This  fluid,  being  much  heavier  than 
the  atmosphere,  does  not  ascend,  like  the  other  gases,  and  become  lost  in 
the  air,  but  accumulates  in  weighty  masses  round  the  outlet.  Plants 
which  are  bathed  in  this  mephitic  air  rapidly  wither,  and  all  animated 
beings  die  from  asphyxia,  unless  their  heads  rise  up  above  the  deadly  at- 
mosphere. In  the  island  of  Java  there  is  a  small  crater  called  Pakereman, 
or  "Valley  of  Death,"  the  amphitheatre  of  which,  after  the  heavy  tropical 
rains,  is  entirely  filled  with  carbonic  acid  gas.  No  plant  grows  in  this 
vast  cavity.  According  to  the  statements  of  Loudon,  the  ground  is  strewn 
with  the  skeletons  of  animals.  At  one  time  there  might  have  been  seen 
in  it  the  remains  of  human  beings  who  had  been  doomed  to  perish  from 
asphyxia  in  the  poisoned  air.  In  Europe  there  is  no  spring  of  carbonic 
acid  which  can  be  compared  to  that  of  Java ;  those  which  have  been 
studied  in  Italy,  Auvergne,  and  on  the  banks  of  the  Rhine  are  most  of 
them  nothing  but  very  inconsiderable  emanations,  filling,  perhaps,  a  con- 
fined cave,  or  the  lower  part  of  a  small  cavity  well  sheltered  from  the 
wind.  Insects,  and  sometimes  a  few  birds,  are  the  only  victims  of  this 
destructive  gas.  The  famous  cave  in  the  vicinity  of  Naples  is  well  known, 
into  which,  to  satisfy  the  idle  curiosity  of  travelers,  the  guides  are  cruel 
enough  to  bring  some  wretched  dogs,  and,  forcing  them  into  the  layers  of 
carbonic  acid  gas  which  hang  over  the  soil,  cause  them  to  pant  for  breath, 
and  ultimately  die.  At  one  time  the  crater,  which  is  now  filled  up  by  the 
gloomy  Lake  of  Avernus,  which  the  ancients  looked  upon  as  the  entrance 
to  the  infernal  regions,  gave  vent  to  so  large  a  quantity  of  carbonic  acid 
gas  that  birds  flying  over  the  lake  fell  as  if  struck  by  lightning ;  hence  is 
derived  the  Greek  name  of  the  lake, "  without  birds." 


SUBMARINE  VOLCASOHS.  •  439 


CHAPTER  LXXL 

SUBMARINE   VOLCANOES. 

The  bed  of  the  sea  is,  of  course,  inaccessible  to  our  observation,  but  still 
there  can  be  no  doubt  that  the  phenomena  of  submarine  volcanoes  resem- 
ble those  of  the  burning  mountains  which  tower  so  high  above  the  ocean. 
Whenever  the  crest  of  an  isle  of  scoriae  rises  above  the  waves,  all  that  we 
see  of  its  eruptions  suflSces  to  prove  that  they  take  place  exactly  in  the 
same  way  as  those  of  the  volcanoes  on  the  main  land.  There  exist,  how- 
ever, in  several  places,  former  submarine  craters  which,  since  their  period 
of  activity,  have  been  upheaved,  with  the  plains  surrounding  them.  The 
history  of  these  craters,  written  legibly  in  their  strata,  is  just  the  same  as 
that  of  other  volcanic  outlets.  Still,  as  would  necessarily  be  looked  for, 
on  account  of  the  pressure  exercised  by  the  immense  body  of  sea-water, 
the  cones  of  debris  which  have  been  formed  under  the  pressure  of  the 
waves  are,  without  any  exception,  more  flattened  than  mountains  of  the 
same  nature  which  have  taken  their  rise  on  the  terra  firma.  With  regard 
to  the  lava  which  issues  from  submarine  fissures,  it  sooner  becomes  solid- 
ified, and  does  not  flow  to  such  great  distances.  Often,  also,  it  is  con- 
vened, under  the  superincumbent  weight  of  the  water,  into  basaltic  col- 
onnades. We  can,  too,  readily  understand  that  the  vapor  must  rapidly 
condense  while  passing  through  the  mass  of  cold  water.  It  is  only  when 
the  mouth  of  the  crater  is  very  close  to  the  surface  of  the  ocean  that  col- 
umns of  vapor  are  freely  discharged  and  ascend  into  the  air. 

Most  submarine  eruptions  which  have  been  known  in  modern  times  have 
taken  place  at  no  great  distance  from  some  of  the  great  insular  or  conti- 
nental volcanoes.  The  Sicilian  Sea,  the  Greek  Archipelago,  the  waters  near 
St.  Michael  in  the  Azores,  the  portion  of  the  Caspian  which  surrounds  the 
Peninsula  of  Apcheron,  the  seas  of  Japan  and  of  the  Aleutian  Isles,  the 
Gulf  ofDarien,and  the  coast  oflceland,  form,  probably,  a  part  of  the  same 
subterranean  regions  of  activity  as  the  volcanoes  situated  on  the  adjacent 
shores.  There  is,  however,  one  volcanic  district  which  is  exclusively  sub- 
marine ;  this  is  the  narrowest  part  of  the  Atlantic,  embraced  between  the 
two  extreme  points  of  the  coasts  of  Guinea  and  Brazil.  In  this  tract  of 
the  ocean  the  water  is  often  agitated  by  violent  shocks,  and  ships  tremble 
as  if  they  had  run  upon  a  sand-bank.  Smoke,  as  if  from  a  conflagration, 
rises  above  the  waves,  and  pumice-stone  and  other  light  scoria)  are  floated 
about  by  the  current.  Even  islands  of  ashes  have  been  noticed  to  emerge 
from  the  midst  of  the  sea,  which,  being  washed  away  by  the  waves,  have 
diminished,  and  ultimately  disappeared.* 

♦  Daussy,  Darwin,  Poulett  Scrope. 


490 


THE  EARTH. 


The  submarine  cones  proceeding  from  the  bottom  of  the  sea  which  resist 
the  action  of  the  water  are  those  which  have  their  layers  composed  of  lava. 
The  group  of  Aleutian  Isles  contain  at  least  two  mountains  which  have 
emerged  from  the  water  within  a  recent  period.  According  to  the  ac- 
counts of  the  Chinese  and  Japanese  chroniclers,  several  volcanoes  have 
risen  from  the  bed  of  the  sea  on  the  coasts  of  Japan  and  the  Corea  during 
the  historical  period.  In  the  year  1007  a  roar  of  thunder  announced  the 
appearance  of  the  volcano  of  Toinmoura,  or  Tanlo,  on  the  south  of  the 
Corea,  and  then,  after  seven  days  and  seven  nights  of  profound  darkness, 
the  mountain  was  seen ;  it  was  no  less  than  four  leagues  in  circumference, 
and  towered  up  like  a  block  of  sulphur  to  a  height  of  more  than  1000  feet.* 
More  than  this,  the  celebrated  Fusi-Yama  itself,  the  highest  mountain  in 
Japan,  is  said  to  have  been  upheaved  in  a  single  night  (?)  from  the  bosom 
of  the  sea  twenty-one  and  a  half  centuries  ago.  With  respect  to  marine 
volcanoes  of  a  more  recent  epoch,  we  may  mention  all  the  isles  of  either 


Fig.  204.  Isle  of  St.  Paul :  the  measuiemeDts  are  in  metres. 
*  Stanislas  Julien,  Corn^^es  Rendus,  vol.  x.,  1840. 


VOLCANO  OF  TAAL. 


491 


extinct  or  still  burning  lava  which  rise  in  pyramids  like  Stromboli,  or  ex- 
tend in  a  graceful  semicircle  like  the  crater  of  St.  Paul  in  the  Indian  Ocean. 
Lakes  also  exhibit  a  number  of  volcanoes  of  the  same  kind.  Such  are 
Momotombo  of  Nicaragua,  and  the  Taal  of  the  Lake  of  Bongbong,  in  the 
island  of  Luzon. 


Fig.  205.  Volcano  of  Taal. 

The  sudden  appearance  of  lava  which  has  most  inipressed  the  popular 
imagination  for  many  years  past,  and  has  also  been  best  studied  by  scien- 
tific men,  is  the  formation  of  hillocks  of  lava  in  the  Santorin  group.  This 
circular  archipelago  is  doubtless  the  remains  of  a  great  cone,  30  miles  in 
circumference,  which  once  rose  in  the  midst  of  the  sea.  In  consequence  of 
the  action  of  the  waves,  earthquakes,  and  subsidences,  the  sides  of  this  cone 
were  broken  in  upon  and  finally  ruptured  by  the  water.  When  the  Hel- 
lenes established  themselves  in  the  islands  of  the  ^gean  Sea,  the  shattered 
mountain  was  divided  into  three  fragments :  one  fragment,  assuming  the 


492 


THE  EABTH. 


form  of  a  crescent,  and  comprehending  the  larger  portion  of  the  former  vol- 
cano, constitutes  the  island  of  Thera,  or  Santorin ;  on  the  west,  the  little 
Isle  of  Therasia  bends  round  in  continuation  of  the  ring  of  land  ;  and,  on 
the  southwest,  a  great  rock,  the  Islet  of  Aspro,  rises  as  if  to  bear  witness 
to  the.  rampart  of  lava  now  disappeared.  The  outer  slopes  of  Santorin  and 
Therasia,  partially  covered  with  pumice-stone  somewhat  resembling  a  coat- 
ing of  snow,  are  rather  gently  inclined  toward  the  sea,  but  the  escarpments, 
turned  in  the  dii'ection  of  the  basin,  which  was  once  the  crater,  are  in  some 
places  nearly  perpendicular  for  a  height  of  650  and  even  1300  feet.  The 
various  layers,  which  correspond  on  the  two  sides  of  the  gnlf — oi^  the  sides 
of  Therasia  and  of  Santorin — are  vividly  marked  out  in  bands  of  a  red, 
yellow,  blue,  black,  or  white  color. 


23?EJaeRu^ 


Fig.  206.  Santorin. 


In  the  centre  of  this  crater,  after  a  series  of  upheavals  and  eruptions,  an 
islet  of  lava  emerged  about  the  year  196  B.C.  It  was  named  Hiera  (Holy), 
and  on  the  summit  a  temple  to  Neptune  was  built.     This  islet,  which  was 


KAlMENI  ISLES.— SANTORIN.  493 

several  times  increased  in  the  centuries  which  followed — in  the  years  46, 
713,  726,  and  1427  AD. — is  now  known  under  the  name  of  Palajo-Kairaeni. 
Not  far  from  this  isle,  another  smaller  one,  Mikro-Kaimeni,  rose  in  1570  or 
1573.  At  the  commencement  of  the  eighteenth  century,  from  1707  to  1711, 
another  mass  of  lava,  Neo-Kalmeni,  an  island  no  less  than  four  miles  in  cir- 
cumference, emerged  within  the  annular  crater  formed  by  the  crescent- 
shaped  Santorin  and  the  Isle  of  Therasia.  In  1768  Neo-Kafmeni  was 
shaken  by  a  violent  eruption.  From  this  date  to  1866  no  visible  change 
took  place  above  the  water,  but  soundings  proved  that  the  bed  of  the  sea 
had  gradually  risen.  At  a  point  near  Mikro-Kaimeni,  a  bank  of  rocks,  sit- 
uated in  1794  at  a  depth  of  80  to  100  feet,  was  in  1835  only  13  feet  from 
the  surface.  "  Such  is  the  singular  fecundity  of  Santorin,"  says  a  histo- 
rian of  this  volcano, "  that  isles  seem  to  grow  up  round  it  like  fungi  in  a 
wood."* 

At  the  end  of  January,  1866,  subterranean  roarings,  a  gradual  sinking 
of  the  ground,  and  the  coloring  of  the  water,  announced  an  approaching 
eruption.  The  centre  of  the  shock  was  felt  just  below  the  little  village  of 
Vulcano,  situated  on  the  edge  of  a  creek  where  ships  used  to  cast  anchor 
in  order  that  the  water,  mingled  as  it  was  with  acid  gases,  might  destroy 
the  molluscs  and  sea-weed  attached  to  their  keels.  On  the  3d  of  Febru- 
ary a  brilliantly  black  mass  of  lava  was  seen,  which  rose  slowly  from  the 
bottom  of  the  water,  and  increased  i^  size  every  day  with  perfect  regu- 
larity. This  mound,  designated  by  the  name  of  George's  Isle,  attained  in 
a  few  weeks  a  height  of  164  feet,  and  ultimately  became  united  to  Neo- 
Kaimeni,  having  filled  up  the  creek  of  Vulcano.  On  the  7th  of  February, 
another  mound,  the  Isle  of  Aphroessa,  rose  at  a  little  distance  to  the  south, 
and,  gradually  filling  up  the  channel  which  separated  it  from  Neo-Kaimeni, 
became  converted  into  a  promontory.  Afterward  other  islets  made  their 
appearance  by  the  side  of  the  two  principal  cones.  All  round  them  the 
sea,  agitated  by  the  gases  which  rose  in  great  bubbles,  exhibited  in  turn 
the  most  diversified  hues.  It  was  in  succession  reddish-colored,  milk-white, 
or  shaded  with  green  or  a  chemical  blue ;  it  was,  besides,  generally  tepid 
or  hot.  The  fish,  either  asphyxiated  or  killed  by  the  heat,  floated  in  mul- 
titudes on  the  surface,  and  mariners  avoided  steering  their  ships  any  where 
near  the  eruption  for  fear  the  pitch  between  their  planks  should  melt  in 
the  water  heated  to  a  temperature  of  160°  to  170°  (Fahr.).  Tlie  summit 
of  the  crater  of  Neo-Kaimeni  was  shaken  by  frequent  explosions.  On  the 
20th  of  February  lumps  weighing  220  pounds  were  suddenly  darted  out 
to  a  distance  of  several  hundred  yards,  showers  of  ashes  fell  upon  the  vines 
of  Santorin,  and  clouds  of  f/e6m,  making  their  escape  from  the  crater,  shot 
up  to  a  height  of  6500  to  9800  feet.  It  was  not  before  the  end  of  the  year 
1866  that  the  cone  of  Geoi-ge's  Island  opened  out  for  itself  a  crater  by  an 
explosion  which  destroyed  the  whole  of  the  upper  portion  of  the  mound. 
But  the  intensity  of  the  eruptive  phenomena  soon  after  gradually  dimin- 
ished. Currents  of  lava  more  than  half  a  mile  long  were  in  some  places 
*  Tegues,  Ilistoire  des  Pliinomhnes  du  Volcan  de  Santorin. 


494 


THE  EARTH. 


more  than  300  feet  in  depth.  It  is  evident  that  the  reason  why  the  mol- 
ten matter  has  thus  formed  in  heaps  close  to  the  outlet,  instead  of  flowing 
in  long  streams,  as  on  the  sides  of  Vesuvius  and  Etna,  is  that  the  lava, 
soon  becoming  cool  by  its  contact  with  the  salt  water,  was  necessarily 
compelled  to  arrest  its  progress.* 


Pig.  207.  Kaimeni  Group. 

The  cones  of  shifting  ashes  which  are  thrown  out  by  the  eruptions  of 
submarine  volcanoes  are  not  able  to  resist  the  action  of  the  waves  for  any 
length  of  time ;  and  however  great  may  be  their  dimensions,  they  are  cer-  , 
*  Fouqud,  Revue  des  Deux-Mondes,  August,  1866. 


ISLE  OF  JULIA. 


495 


tain  ultimately  to  disappear,  unless  they  are  based  on  solid  foundations 
which  have  entirely  emerged  from  the  water.  As  an  example  of  this  we 
may  mention  the  celebrated  Julia,  or  Graham's  Island,  which  appeared  in 


Ilg.  208.  Graham's  Island,  or  Isle  of  Jnlia. 

July,  1831,  throwing  up  heaps  of  dark-colored  scoriae  about  25  miles  south 
of  the  shores  of  Selimonte,  in  Sicily.  An  English  captain,  proud  of  being 
able  to  increase  the  British  domains,  hurried  to  hoist  his  flag  over  the 
smoking  stones.  The  islet  gradually  increased  round  the  crater,  and  be- 
fore long  it  measured  as  much  as  four  miles  round.  But,  at  the  conclu- 
sion of  the  volcanic  eruption,  the  work  of  demolition  commenced,  and,  in 
conformity  with  M.  Constant  Prevost's  prediction,  the  slope  oi  debris  was 
gradually  undermined  at  the  base  by  the  waves  and  currents.  In  October 
nothing  remained  but  a  little  mound.  Six  months  after,  the  newly-discov- 
ered island,  which  Avas  also  claimed  by  the  King  of  Naples  through  his  di- 
plomatists, was  nothing  more  than  an  oval  reef  about  half  a  mile  long.  A 
few  years  later  the  sounding-line  showed  a  depth  of  787  feet.  In  July, 
1863,  the  isle  again  appeared,  and  in  a  few  weeks  rose  to  the  height  of 
200  to  260  feet ;  but  it  existed  only  for  a  short  space  of  time,  for  it  soon 
again  sank,  being  demolished  stone  by  stone  by  the  dash  of  the  waves. 
It  appears,  however,  that,  previously  to  1831,  the  volcano  had  made  its 
appearance  on  one  or  two  other  occasions.  It  is  said  that  a  smoking  isl- 
and existed  in  this  spot  about  the  year  1801,  and  the  shoal  is  pointed  out 
in  old  charts.  This  island,  first  rising  up  above  the  waves  and  then  sink- 
ing down  again  into  the  depths  of  the  sea,  seems  to  recall  the  recollection 
of  that  mysterious  country  mentioned  in  the  "Arabian  Nights,"  which 
plunged  down  into  the  ocean  just  at  the  moment  when  the  voyagers  were 
going  to  land  on  it. 

Near  the  island  of  San  Miguel,  one  of  the  Azores,  there  is  another  sub- 
marine volcano,  which  likewise  vomits  out  at  each  of  its  great  eruptions  a 
temporary  cone  of  scoria?,  which  rises  above  the  level  of  the  sea.     In  the 


496  THE  EARTH. 

years  1658, 1691, 1720,  and  1812,  a  smoking  islet  made  its  appearance,  and 
on  each  occasion  it  was  destroyed  after  a  few  weeks  of  existence.  Never- 
theless, in  1812,  an  Englishman  found  time  to  take  possession  of  it  in  the 
name  of  his  government,  and  to  give  it  the  name  of  "  Sabrina."  In  1867 
a  fresh  eruption  took  place  at  about  the  same  spot,  but  the  volcanic  cone 
did  not  reach  the  surface  of  the  sea,  and  M.  Fouqu^,  the  indefatigable  ex- 
plorer of  volcanoes,  noticed  nothing  but  floating  scoriae,  gases  thrown  out, 
and  flames  dancing  over  the  water.  In  the  Icelandic  seas,  the  land  of 
Nynoe,  which  appeared  in  1783  at  a  point  31  miles  to  the  southwest  of 
Cape  Rekianess,  enjoyed  a  much  longer  life,  for  it  lasted  a  whole  year. 
There,  just  as  in  the  seas  of  Sicily  and  the  Azores,  the  ashes  washed  away 
by  the  waves  are  deposited  at  the  bottom  of  the  water  in  vast  layers  of 
tufa  mingled  with  shells  and  other  debris.  Some  day  or  other  these  beds 
of  volcanic  stone  will  appear  on  the  sui'face,just  as  the  tufas  of  the  Euga- 
nean  hills  in  the  valley  of  the  Po,  and  the  Phlegraean  fields  at  Naples,  and 
will  tell  the  tale  of  the  submarine  eruptions  of  the  present  period. 


PERIODICITY  OF  ERUPTIONS.  497 


CHAPTER  LXXn. 

PERIODICITY    OF    ERUPTIONS. — INFLUENCE    OF   TEMPERATURE    ON  VOMANIC 
PHENOMENA- — EXTINCTION    OF    FURNACES    OF   LAVA. 

One  of  the  most  important  questions  in  respect  to  volcanoes  is  that  of 
the  order  in  which  their  phenomena  take  place.  Every  thing  in  nature 
acts  in  sure  conformity  to  regular  laws  of  periodicity ;  but  when  this  rule 
has  to  be  applied  both  over  vast  spaces  and  long  intervals,  it  may  readily 
remain  unknown  to  us  for  a  very  long  time.  Tlie  fact  is,  that  the  rhythm 
of  the  great  volcanic  revolutions  has  not  yet  been  discovered,  and,  up  to 
the  present  time,  the  whole  of  these  events  appear  to  us  as  if  they  were  a 
perfect  chaos.  Even  in  the  volcanic  region  which  is  the  best  known,  and 
which  savants  have  the  best  studied,  that  is,  in  the  area  which  includes 
Southern  Italy,  Sicily,  and  the  Lipari  Islands,  the  succession  of  movements 
(except  as  regards  Stromboli)  has  taken  place  with  the  greatest  apparent 
want  of  order.  Etna  and  Vesuvius  have  remained  in  a  state  of  repose  for 
centuries,  and  then  suddenly,  and  after  unequal  intervals,  they  have  expe- 
rienced sometimes  one  convulsion  only,  sometimes  a  series  of  shocks  more 
or  less  violent  and  numerous.  Besides,  as  we  have  seen,  there  is  no  neces- 
sary coincidence  between  the  phenomena  of  the  two  volcanoes.  Some- 
times, indeed,  it  happens  that  a  period  of  extraordinary  activity  in  one 
volcano  is  contempoi*ary  with  protracted  tranquillity  in  the  other.  True 
enough,  during  the  dark  night  of  the  Middle  Ages,  phenomena  like  this 
were  almost  entirely  lost  sight  of  in  history,  but  documents  collected  since 
the  sixteenth  century  evidently  prove  that  the  geologist  must  limit  him- 
self to  studying  the  symptomg  of  periodicity  in  each  smoking  mountain 
by  itself. 

In  this  last  respect  there  is  no  want  of  evidence  which  renders  highly 
probable  the  existence  of  some  sympathetic  tie  between  the  eruptions  of 
volcanoes  and  the  more  or  less  regular  phenomena  of  the  surrounding  at- 
mosphere. This,  indeed,  is  a  proverbial  article  of  faith  with  mariners  as 
regards  a  large  number  of  active  craters.  The  fishermen  of  Stromboli 
have  for  centuries  j\ll  agreed  in  stating  that  the  mountain  serves  as  a  ba- 
rometer for  them  in  pointing  out  the  approach  of  winds  and  storms  by  a 
great  increase  of  violence  in  its  eruptions.  At  the  time  of  the  autumnal 
equinox,  as  well  as  in  winter,  the  boiling  lava  in  the  crater  runs  out  much 
more  often  through  the  outlet,  and  sometimes  opens  out  a  way  of  issue  in 
the  sides  of  the  mountain,  so  as  to  flow  down  to  the  sea.  The  fact  is,  that 
the  atmospheric  pressure*  above  tHe  column  of  lava  being  diminished  dur- 
ing stormy  weather,  does  not  act  with  the  same  ^nei^y  on  the  compressed 
mass ;  the  molten  matter  rises  more  rapidly  in  the  crater,  and  flows  out 
in  greater  abundance.     Added  to  this,  as  the  smoke  of  the  volcano  gen- 

Ii 


498  T^^  EABTM. 

erally  mounts  up  a  thousand  yards  above  the  level  of  the  sea,  and  •some- 
times rises  in  a  column  to  the  higher  regions  of  the  atmosphere,  the  con- 
tests which  take  place  among  the  aerial  currents  may  often  be  seen  more 
or  less  clearly ;  thus,  by  experience,  a  knowledge  may  be  obtained  before- 
hand of  the  changes  of  weather  which  will  gradually -make  their  way  down 
from  the  sky  above.  "By  the  smoke  of  this  volcano,"  said  Pliny,  eighteen 
centuries  ago,  "  the  natives  can  predict  the  winds  three  days  in  advance, 
which  leads  them  to  believe  that  these  vapors  are  in  obedience  to  -^olus." 

The  inhabitants  of  Lipari  say,  also,  that  the  vapors  from  the  crater  of 
Volcano  form  clouds  of  much  greater  volume  when  storms  are  brewing. 
This,  then,  would  be  another  gigantic  barometer,  regularly  indicating  the 
diminished  pressure  of  the  atmosphere.  According  to  both  travelers  and 
natives,  the  epoch  of  the  equinoxes,  when  the  monsoons  blow,  is  the  time 
when  the  eruptions  of  the  Peak  of  Ternate,  Taal,  and  other  volcanoes  of 
the  Indian  Archipelago  are  most  terrible.  In  like  manner,  in  the  Isle  of 
Chiloe,  Fitzroy  was  told  that  the  eruptions  of  Osorno  always  announced 
the  approach  of  fine  weather,  and,  in  consequence,  an  increase  in  the  weight 
of  the  column  of  air.  With  regard  to  phenomena  other  than  the  oscilla- 
tions of  the  aerial  masses,  these  may  also  be  foretold  by  means  of  the  vol- 
canic movements,  if  we  are  to  put  faith  in  the  statements  of  those  who 
live  at  the  very  foot  of  the  smoking  mountains.  Thus,  in  Japan,  the  vol- 
canoes generally  begin  to  vomit  out  lava  about  the  time  of  the  flow  of  the 
tide,  and  inundations  caused  by  exceptionally  high  tides  always  take  place 
after  eruptions  and  earthquakes.*  In  1827,  Scuderi,  a  Sicilian,  tried  to 
prognosticate  all  the  meteorological  phenomena  by  the  form  and  direc- 
tion taken  by  the  masses  of  vapor  which  were  vomited  out  by  the  crater 
of  Etna,  f 

M.  Emile  Kluge,  by  classifying  all  the  known  eruptions  in  seasons  and 
months,  has  ascertained  that  these  crises  take  place  in  summer  especially, 
and  that  earthquakes  are  more  frequent  in  winter.  According  to  this  ge- 
ologist, there  is  no  doubt  that  the  eruptions  of  volcanoes  depend  on  the 
changes  of  seasons.  The  melting  of  the  snow  and  ice,  the  falls  of  rain,  the 
oscillations  in  temperature,  and  the  weight  of  the  air,  are,  in  his  idea,  the 
real  causes  of  the  subterranean  fires ;  the  latter,  too,  being  the  mere  result 
of  chemical  reaction,  and  among  the  purely  external  phenomena  of  the 
planet.  Not,  therefore,  in  the  abysses  of  a  sea  of  fire,  but  at  a  depth  of 
six  to  nine  miles  at  most,  must  we  seek  for  the  furnaces  in  which  the  burn- 
ing matter  is  elaborated. J 

Nevertheless,  although  we  may  be  warranted  in  looking  upon  the  year 
itself,  with  its  return  of  seasons  and  atmospheric  phenomena,  as  a  kind  of 
day  in  the  life  of  volcanoes,  we  are  none  the  less  in  complete  ignorance 
in  respect  to  the  great  secular  periods  of  Plutonic  activity  in  the  various 
parts  of  the  woi-ld.  Like  all  terrestrial  phenomena,  that  of  the  eruption 
of  lava  and  ashes  is  linnteA  in  its  duration.     The  volcanoes  which  rise  up 

*  Siebold,  quoted  by'Perrey.  +  Memoire  delV  Academia  Gioenia. 

t  Ueber  die  Pertodicitat  vulcanischer  Ausbru-:ke ;  Neues  Jahrb.fur  Mineral.,  1 862,  part  v. 


EXTINCTION  OF  VOLCANOES. 


499 


Fig.  20i>.  Coulee  ot"  Pny  de  Pariou. 

out  ot  the  ground  are  extinguished  either  after  a  short  existence  or  after 
thousands  of  eruptions.  Over  the  whole  surface  of  the  earth  there  are  a 
large  number  of  former  volcanoes  the  nature  of  which  has  been  disclosed 
to  us  by  modern  geology  alone.  Some  date  from  an  epoch  so  remote  that 
beds  of  modern  formation  have  to  a  great  extent  covered  their  sides  and 
tilled  up  their  craters.  Others,  like  the  hills  of  Auvergne,  are  still  visible, 
with  their  cones  of  scoria?  or  their  domes  of  trachyte,  their  tissures  and 
cheires  of  lava,  such  as  they  once  were  when  the  plains  at  their  bases  were 
arms  of  the  sea.  Among  these  well-preserved  volcanoes  there  are,  indeed, 
some — especially  that  of  Denise,  near  the  Puy-en-Velay — which  were  in  a 
state  of  full  activity  at  an  epoch  when  man  had  already  established  him- 
self in  the  adjacent  districts,  for  in  the  tufa  of  their  eruptions  skeletons 
have  been  found  of  the  ancient  inhabitants  of  Gaul.  Lastly,  numerous 
volcanoes  which  have  burnt  during  the  historical  period  are  now  extinct, 
and  perhaps  forever.  The  cycles  of  these  lava-furnaces  are  doubtless  con- 
nected with  those  of  the  continents  themselves ;  the  configuration  of  land 
and  sea  must  change  before  these  furnaces  can  again  be  lighted  up.  Con- 
tinents and  oceanic  basins  must  also  shift  their  position  on  the  surface  of 
the  globe  before  they  can  be  extinguished. 


500  ^^^  EAETH. 


CHAPTER  LXXm. 

EARTHQUAKES. — ^VIBEATIONS   OF   THE    GROUND. — VARIOUS    HYPOTHESES. 

As  volcanic  eruptions  suflGiciently  show,  this  planet  is  not  the  immova- 
ble mass  which  our  imaginations  depict  it  when  comparing  it  to  the  at- 
mosphere which  surrounds  it,  to  the  ever-mobile  waves  of  the  ocean,  or 
even  to  the  animated  beings  which  wander  over  its  surface.  On  the  con- 
trary, the  ground  which  we  tread  under  our  feet  vibrates  very  frequently. 
Without  alluding  to  those  great  shocks  which  overthrow  cities,  bring 
down  the  sides  of  mountains,  and  open  vast  cracks  across  plains,  there  are 
other  less  violent  vibrations;  which  have  been  recorded  by  the  annalists 
of  geological  history,  and  may  be  reckoned  by  thousands  as  regards  civil- 
ized countries  and  modern  times  alone.  There  can  be,  however,  no  doubt 
that  the  great  tnajority  of  slight  earthquakes  pass  unnoticed,  being  blend- 
ed, especially  in  towns,  with  the  confused  rumbling  of  noises  and  murmurs. 
Various  seismological  instruments,  recently  invented  or  brought  to  perfec- 
tion, reveal  a  large  number  of  oscillations  which  it  would  be  impossible  to 
discover  in  any  other  way.  An  attentive  observation  of  the  levels  of  air- 
bubbles  and  of  micrometrical  threads  reflected  on  the  surface  of  a  bath  of 
mercury  has,  indeed,  warranted  M.  d'Abbadie  in  asserting  that  the  earth 
is  in  a  state  of  constant  vibration.  The  intervals  of  immobility  which  he 
has  noted  have  never  exceeded  thirty  hours. 

What  is  the  cause  of  these  trepidations  of  the  ground?  A  great  num- 
ber of  savants,  who  have  accepted  the  hypothesis  of  a  pt/rijj/degeton,  or 
central  fire,  do  not  hesitate  to  look  upon  these  vibrations  of  the  earth  as 
the  repercussion  of  the  undulations  of  the  great  burning  sea.  Each  of  the 
shocks  which  are  felt  on  the  surface  of  the  earth  would  then  take  its  rise 
below  the  envelope  of  the  planet,  and  would  be  at  first  produced  in  the 
form  of  a  current  or  tide  in  the  burning  mass  which  is  supposed  to  exist. 
As  Humboldt  says,  an  earthquake  would  be  "  the  reaction  of  the  liquid 
nucleus  against  the  outer  crust."  Added  to  this,  most  geologists  who 
base  their  arguments  on  the  hypothesis  of  a  central  fire  admit  that  earth- 
quakes must  necessarily.be  in  connection  with  volcanic  phenomena,  and 
that  they  invariably  proceed  from  the  same  cause.  Following  out  the 
comparison  which  must  always  present  itself  to  the  mind,  the  mouths  of 
volcanoes  are  safety-valves,  and,  on  account  of  the  obstruction  of  these  out- 
lets, the  pent-up  lava  or  vapor  shakes  the  superincumbent  layers  of  the 
ten-estrial  envelope,  seeking  to  find  some  way  of  issue.  This  theory  has 
the  merit  of  being  very  simple,  and,  in  a  large  number  of  cases,  seems  to 
harmonize  very  satisfactorily  with  the  facts  that  have  been  observed. 
But  we  must  never  forget,  however  probable  this  hypothesis  as  to  the  vol- 


DISTRIBUTION  OF  EARTHQUAKES.  501 

canic  action  may  be,  it  lias  not  as  yet  become  a  certainty ;  and  the  duty 
for  the  geographer  still  is  to  study  events  impartially,  and  to  suspend  his 
judgment  until  a  satisfactory  conclusion  evidently  results  from  the  whole 
body  of  facts  observed. 

In  the  first  place,  it  is  important  to  know  if  those  regions  on  the  sui-face 
of  the  globe  in  which  earthquakes  take  place  with  the  greatest  frequency 
are  distinguished  from  other  parts  by  any  peculiar  features  in  the  form  of 
their  vertical  outline,  or  in  the  nature  of  their  rocks.  The  volcanic  dis- 
tricts in  Europe,  such  as  the  environs  of  Vesuvius  and  Etna,  the  islands  of 
Santorin  and  Milo,  and  the  south  of  Iceland,  are  not  the  only  places  which 
are  subject  to  severe  shocks ;  the  former  districts,  too,  have  never  been  so 
violently  agitated  as  the  mountains  of  the  Abruzzi  and  Calabria,  the  islands 
of  Rhodes  and  Cyprus,  the  limestone  districts  of  Carniola  and  Istria,  the 
Alps  of  the  Valais,  the  environs  of  Basle,  certain  plateaux  in  Spain,  and 
the  hills  at  the  mouth  of  the  Tagus.  The  mountains  of  Scotland,  and  es- 
pecially those  in  the  county  of  Perth,  have  also  experienced  repeated 
shocks :  out  of  two  hundred  and  twenty-five  earthquakes  recorded  in  the 
British  Isles,  eighty-five  have  taken  place  in  this  one  county.  In  Africa, 
the  soil  of  Algeria,  so  rich  in  saline  and  thermal  springs,  but  devoid  of  vol- 
canic craters,  is  sometimes  very  severely  shaken.  The  districts  of  the 
Nile,  which  are  likewise  without  volcanoes,  have  also  sufiered  much  from 
subterranean  movements.  In  Asia,  the  peninsula  of  Guzerat,  a  spot  in 
which  astonishing  modificati6ns  of  the  shape  of  the  coasts  were  produced 
during  a  great  earthquake,  is  situated  more  than  1240  miles  from  the  near- 
est volcanoes,  the  Demavend  and  the  burning  mountains  of  Thian-Chan ; 
but,  on  the  other  hand,  the  Philippines  and  Japan,  which  are  volcanic  coun- 
tries, are  also  frequently  agitated  by  movements  of  the  ground.  Again, 
the  sea-coast  of  Syria,  the  towns  of  Aleppo  and  Antioch,  the  scenes  of  some 
of  the  most  destructive  earthquakes  that  are  recorded  in  history,  no  lon- 
ger possess  very  active  volcanoes,  and  the  lavas  of  the  Djebel-Hauran,  on 
the  southeast,  have  long  been  extinct.  In  South  America  most  of  the 
great  shocks  have  taken  place  in  the  region  of  the  Andes,  or  not  far  from 
their  bases.  The  Argentine  town  of  Mendoza,  which  was  overturned  in 
the  violent  earthquake  of  1861,  is  comparatively  not  far  from  a  lava-fur- 
nace, since  the  volcano  of  Maypu  rises  at  a  distance  of  only  87  miles.  The 
equatorial  Andes  are  often  convulsed  by  violent  oscillations  of  the  soil,  and 
are  also  the  theatre  of  great  volcanic  activity,  many  of  their  summits  be- 
ing domes  of  trachyte,  or  craters  still  vomiting  out  ashes,  mud,  or  smoke. 
Nevertheless,  according  to  the  testimony  of  Boussingault,  the  most  ener- 
getic shocks  experienced  in  Columbia — those  which  destroyed  the  towns 
of  Latacunga,  Riobamba,  Honda,  Merida,  and  Burquesimeto,  and  were  sim- 
ultaneously felt  over  a  very  extended  area — presented  no  coincidence 
whatever  with  any  volcan^phenomena,  and  their  centre  of  agitation  was 
situated  at  a  considerable  distance  from  the  smoking  peaks.*  The  plateau 
of  Caraccas,  celebrated  for  the  catastrophe  of  1812,  is  situated  more  than 
600  miles  eastward  of  the  Grenadini  volcanoes  of  Huila  and  Tolima,  and 
•  Annalea  de  Chimie  et  de  Physique,  185.'>. 


502  ^^^  EARTH. 

« 

at  rather  a  less  distance  from  the  craters  of  the  Antilles,  from  which  it  is 
separated  by  wide  arms  of  the  sea.  Finally,  the  region  in  North  America 
where  oscillations  of  the  ground  are  most  frequent  and  most  severe  is  the 
alluvial  plain  of  the  Mississippi,  far  distant  from  any  volcanic  disti-ict,  and 
even  from  any  great  chain  of  mountains.  Thus,  although  the  history  of 
earthquakes  is  known  only  for  a  few  centuries,  and  over  but  a  small  por- 
tion of  the  earth's  surface,  it  is  certain  that  severe  oscillations  of  the 
ground  are  felt  in  countries  the  most  diverse,  which  bear  no  resemblance 
to  one  another  either  in  their  formation  or  their  aspect.  The  only  fact 
which  seems  well  established  is,  that  shocks  are  more  frequent  in  moun- 
tainous than  in  flat  countries.  Nevertheless,  if,  as  Mr.  Mallet  thinks,  all 
earthquakes  not  followed  by  an  eruption  are  "  incomplete  efforts  to  open  a 
volcano,"  if  they  are  produced  by  the  endeavors  made  by  the  planet  to  get 
rid  either  of  gas  or  the  molten  matter  within,  the  ground  ought  to  be 
most  frequently  agitated  in  continental  plains,  far  from  volcanoes  and 
mountains ;  for  in  those  localities  there  would  be  no  natural  "  vent-holes" 
through  which  to  discharge  the  ovei-flow  of  the  interior  fluids,  and  there, 
too,  according  to  the  common  theory,  the  terrestrial  layers  must  be  the 
thinnest. 

Those  who  look  upon  every  volcano  as  a  safety-valve  for  the  adjacent 
regions  put  forward  in  favor  of  their  theory  certain  facts  which  have  at- 
tained to  the  dignity  of  legends,  although  their  reality  is  far  from  being 
certain,  as  M.  Otto  Volger  has  more  than  siffficiently  proved.*  Thus  it  is 
said  that,  at  the  time  of  the  earthquake  at  Lisbon,  Vesuvius,  which  was 
vomiting  out  a  considerable  quantity  of  vapor,  suddenly  sucked  in  the 
cloud  which  it  was  throwing  out,  and  that  the  current  of  lava  issuing  from 
its  sides  was  suddenly  stopped.  But  these  statements  are  founded  solely 
on  a  much  less  precise  expi'ession  in  the  account  which  Kant  the  philoso- 
pher devoted  to  the  catastrophe  at  Lisbon.  Humboldt  tells  us  "that, 
after  having  vomited  out  for  three  months  a  high  column  of  smoke,  the 
volcano  of  Pasto  ceased  to  throw  out  vapor  at  the  exact  moment  when,  at 
a  distance  of  248  miles,  the  earthquake  of  Riobamba  and  the  mud-eruption 
of  Tunguragua  caused  the  death  of  30,000  to  40,000  Indians.!  Even  the 
great  name  of  Humboldt  must  not,  however,  lead  us  to  forget  that,  on  the 
plateaux  of  the  Andes,  communication  is  both  rare  and  difficult,  and  that 
the  population  scattered  over  that  space  of  248  miles  does  not  afford  all 
the  guarantees  which  would  be  considered  requisite  in  scientific  observa- 
tion. Lastly,  the  assertion  that  Stromboli  relaxed  its  incessant  activity 
during  the  Calabrian  earthquake  in  1783  is  based  on  nothing  but  the 
vaguest  information.  According  to  the  pamphlets  of  that  date,  all  the 
Lipari  Isles  were  to  be  swallowed  up  in  the  sea,  leaving  but  a  few  shoals 
to  mark  the  places  they  once  filled !  As  may  be  seen,  the  facts  which 
have  been  brought  forward  as  the  foundatioi^f  the  theory  that  all  earth- 
quakes are  caused  by  the  movements  of  lava  or  vapors  are  deficient  in  the 
requisite  authenticity,  and  can  not  be  looked  upon  as  exempting  geologists 
from  the  necessity  of  direct  observations. 

*  Erdbehen  in  der  Schweiz,  vol.  iii,,  p.  385.  t  Tableaux  de  la  Nature,  vol.  ii. 


CAUSES  OF  EARTHQUAKES.  503 


CHAPTER  LXXIV. 

EARTHQUAKES    OP    VOLCANIC    ORIGIN. — SUBTERRANEAN    DOWNFALLS. — 
EXPLOSIONS   OF   MINES   AND   POWDER-MILLS. 

There  are  a  certain  number  of  eases  in  which,  independently  oi  any 
theory,  we  can  without  difficulty  substantiate  a  relation  of  cause  and  effect 
between  a  volcanic  eruption  and  an  earthquake.  Thus,  when  the  sides  of 
a  smoking  mountain,  such  as  Etna  or  Kilauea,  are  suddenly  cleft  asunder 
to  pour  forth  a  stream  of  lava,  and  at  the  same  time  the  ground  is  strongly 
agitated,  it  is  evident  that  the  earthquake  is  caused  by  the  fracture  of  the 
volcano.  This  local  phenomenon  is  precisely  analogous  to  that  produced 
by  the  explosion  of  a  mine  or  a  powder-mill.  When  the  fissure  is  of  a 
considerable  length  and  the  fractured  sides  of  the  volcano  present  a  great 
thickness,  the  shock  is  a  violent  one,  and  reverberates  in  long  oscillations 
in  all  the  adjacent  districts.  When,  on  the  contrary,  the  rocks  of  the 
volcano,  having  been  diminished  in  thickness  and  partially  melted  by  the 
rising  lava,  yield  more  easily  to  the  pressure  which  bursts  them,  the  ex- 
plosion is  only  felt  in  the  immediate  vicinity  of  the  fissure.  Thus,  at  the 
time  of  the  last  great  eruption  of  Etna,  the  trepidations  of  the  ground, 
which  coincided  with  the  formation  of  the  fissure,  were  in  general  very 
slight,  and  the  sharpest  of  them — which  was,  however,  perceptible  in  the 
town  of  Aci  Reale — was  not  felt  beyond  the  Etnean  region  properly  so 
called.*  History  also  aflTords  several  examples  of  volcanic  eruptions  dur- 
ing which  the  ground  was  not  perceptibly  shaken.  In  May,  1 855,Vesu- 
vius  vomited  out  a  considerable  quantity  of  lava  mthout  the  least  trace 
of  any  motion  of  the  ground  being  perceived  either  m  the  observatory  on 
the  volcano  or  at  Naples. 

When  the  ground  of  a  volcanic  region  is  convulsed  by  shocks,  and  we 
are  unable  to  observe  the  least  connection,  either  as  regards  coincidence 
or  immediate  succession,  between  these  phenomen.'^and  the  eruption  of  a 
cone  of  ashes  or  the  emission  of  a  current  of  lava,  we  evidently  have  no 
scientific  reason  for  asserting  with  any  certainty  that  these  shocks  origi- 
nate in  the  subterranean  furnace  of  burning  matter,  or  that  they  are  caused 
by  vapor  endeavoring  to  break  through  the  terrestrial  crust.  For  still 
stronger  reasons,  a  similar  assertion  would  be  contrary  to  all  the  rules  of. 
scientific  observation  when  applied  to  earthquakes  which  take  place  far 
from  any  volcano.  Certainly,  according  to  the  "  safety-valve"  hypothesis, 
oscillations  of  the  ground  ought  to  take  place  just  in  those  very  localities 
of  the  planetary  envelope  in  which  there  exists  no  orifice  communicating 
with  the  lava.  But  how  is  it,  then,  that  undulations  of  the  soil  are  not 
*  Mariano  Grassi,  Eruzione  deW  Etna. 


504  THE  EARTH. 

constantly  produced  at  places  far  from  these  gigantic  vent-holes  situated 
on  the  sea-coast  ?  Why  is  it,  too,  that  frequent  eruptions  of  Vesuvius  and 
Etna  did  not  precede  the  Calabrian  earthquakes,  and  afford  an  issue  to  the 
pent-up  vapor  and  lava? 

The  hypothesis  that  volcanic  forces  are  th%  cause  of  earthquakes  being 
one  that  can  not  be  justified  in  every  case,  we  must  have  recourse,  in  re- 
spect to  many  of  these  phenomena,  to  some  other  theory — one,  in  fact, 
which  in  all  time  has  suggested  itself  to  the  minds  of  various  people,  and 
was  taught  by  the  Greek  philosophers.  Some  t-v^  thousand  years  ago 
Lucretius  propounded  this  idea  in  magnificent  language — an  idea  which 
has  now  been  scientifically  adopted  by  Boussingault,Virlet,  Otto  Volger, 
and  other  geologists. 

"  Learn,  now,  the  cause  of  earthquakes,  and  first  be  assured  that  the  in- 
terior of  the  globe  is,  like  the  surface,  filled  with  winds,  caverns,  lakes, 
precipices,  stones,  rocks,  and  a  large  number  of  rivers,  the  impetuous  waves 
of  which  hurry  along  in  their  course  numerous  submerged  blocks.  The 
shakings  of  the  surface  of  the  globe  are  occasioned  by  the  Tailing  in  of  en- 
ormous caverns  which  time  has  succeeded  in  destroying.  Whole  moun- 
tains thus  sink  in  ruin,  and  the  violent  and  sudden  shock  is  spread  far  and 
wide  in  terrible  vibrations.  Thus  a  chariot,  the  weight  of  which  is  not, 
however,  very  considerable,  makes  all  the  houses  near  tremble  as  it  passes, 
and  the  fiery  steeds,  drawing  behind  them  the  iron-armed  wheels,  shake  all 
the  places  round.  It  might  well  happen  that  an  enormous  mass  of  earth 
should  fall  by  reason  of  decay  into  some  great  subterranean  lake,  and  that 
the  globe  should  tremble  in  a  series  of  undulations.  In  like  manner,  on 
the  surface  of  the  earth,  a  vessel  filled  with  liquid  in  a  state  of  agitation 
can  not  resume  its  equilibrium  until  the  water  contained  in  it  has  found 
its  level." 

Various  savants  have  recently  collected  a  large  number  of  facts  which 
are  in  favor  of  the  theory  of  earthquakes  once  propounded  by  Lucretius, 
although  only  genenfcy,  and  without  the  necessary  proofs.  In  a  vast 
number  of  cases  this  theory  is  certainly  the  true  one,  for  it  is  often  possi- 
ble to  catch  in  the  act,  so  to  speak,  the  phenomena  which  give  rise  to  the 
oscillations  of  the  ground  and  subterranean  thunders.  Thus  great  land- 
slips, such  as  those  ofi  the  Diablerets,  Rossberg,  aijd  other  mountains  of 
the  Alps,  have  caused  real  earthquakes,  the  waves  of  which  were  felt  at  a 
considerable  distance  from  the  scene  of  the  catastrophe.  Even  the  falls 
oi moraines.,  seracs,  and  avalanches  of  snow  shake  the  ground  very  severely 
over  considerable  areas,  so  much  so  that  in  the  mountains  of  Allemont, 
in  Dauphiny,  the  inhabitants  consider  all  the  vibrations  of  the  ground  as 
the  reverberations  of  distant  downfalls  of  snow  or  rocks.* 

The  subsidence  of  rocks  or  shifting  soil  is  accompanied  by  similar  phe- 
nomena. In  September,  1814,  near  Alais,  for  twenty-four  hours  a  series  of 
detonations  were  heard  like  a  cannonade,  and  then,  after  a  formidable 
cracking  noise,  the  ground  sank  13  feet  for  a  breadth  of  more  than  88 
*  Fournet,  ^nwa/ea  des  Sciences  Physiqites  de  Lyon,  vol.  viii.,  1845. 


CAUSES  OF  EARTHQUAKES.  505 

yards.  Not  far  from  the  town  of  Wagstadt,  in  Silesia,  in  182  7,  a  tract  of 
more  than  two  acres  in  area  sank  in  a  similar  way  with  a  great  crash.  In 
Carniola,  where  earthquakes  are  not  unfrequent,  heaps  of  fallen  rocks  are 
noticed  in  the  numerous  caverns,  which  heaps  correspond  with  the  funnel- 
shaped  cavities  on  the  8urfa<jp  of  the  ground.  These  subsidences,  which 
man  sometimes  pei-sonally  witnesses,  either  in  districts  hollowed  out  by 
natural  caves,  or  in  mining  regions  pierced  with  subterranean  galleries, 
may  cause  local  shocks,  or,  in  proportion  to  the  mass  of  rocks  falling,  give 
rise  to  earthquakes  felt  simultaneously  over  vast  extents*  of  country.  In 
fact,  certain  rocky  strata  sometimes  leave  intervals  between  them  of  very 
considerable  depth,  as  may  easily  be  noticed  on  the  sides  of  mountains ; 
and  they  may,  besides,  be  composed  of  substances  which  are  more  or  less 
easily  dissolved  and  washed  away  by  the  infiltrated  water.  When  these 
voids  extend  so  far  that  the  rocks  above,  sometimes  hundreds  or  even 
thousands  of  yards  in  thickness,  can  no  longer  maintain  their  position  by 
means  of  their  own  cohesion,  the  whole  mass  must  necessarily  fall  down 
on  the  beds  bendath.  It  is,  indeed,  impossible  to  imagine  that  it  can  bo- 
otherwise  ;  the  enormous  quantities  «f  salt,  gypsum,  lime,  silex,  and  other 
substances  which  springs  bring  up  to  the  surface  must  of  necessity  leave 
great  voids  in  the  depths  below,  and,  in  consequence,  the  subsidence  of  the 
rocks  above  these  vacant  spaces  becomes  inevitable.  Only  imagine,  if  it 
is  possible,  the  potency  of  the  shock  produced  by  the  sudden  fall  of  sev- 
eral millions  of  cubic  yards.* 

Earthquakes  produced  by  artificial  causes  inW)  way  differ  from  natural 
shoWBS  in  the  effects  which  they  produce ;  they,  indeed,  furnish  us  with 
excellent  terms  of  comparison.  The  explosions  of  mines  and  the  passage 
of  heavily-laden  trains  cause  a  motion  of  the  ground  over  areas  increasing 
in  extent  as  the  initial  pressure  is  more  considerable  and  as  the  rocks  pre- 
sent a  greater  degree  of  elasticity.  Cannonades,  the  reaction  of  which  on 
the  earth  is,  however,  trifling  in  proportion  to  the  effect  produced,  are 
heard  at  distances  which  seem  prodigious,  if  the  ear  is  applied  to  the  sur- 
face of  the  agitated  ground.  Vibrations  of  the  layers  of  the  earth — in 
fact,  real  earthquakes — are  thus  prolonged  for  more  than  250,  or,  indeed, 
for  375  miles.  Thus,  is  1832,  the  bombardment  of  Antwerp  was  heard,  it 
is  said,  in  the  Erzgebirge,  in  the  centre  of  Germany.  Twenty-five  years 
ago,  at  the  time  of  the  explosion  of  the  powder-mills  of  Mentz,  a  very  large 
area  of  ground  was  made  to  tremble.  More  than  10,000  lbs,  weight  of  the 
gunpowder  exploded  (the  greater  part)  blew  up  in  open  vaults,  and  could 
not,  therefore,  react  on  the  ground ;  yet  the  shock  was  felt,  either  as  a 
slight  trembling  of  the  ground  or  as  distant  thunder,  as  far  as  100  to  125 
miles  away — far  beyond  the  districts  to  which  the  sound  of  the  detonation 
was  carried  by  the  wind.  The  shock  was  felt  at  several  towns  in  Suabia, 
at  Wurzburg,  at  Kissingen,  in  Fulda  and  Meiningen,  in  Thuringia,  near 
Cassel,  and  at  Wildungen^  Doubtless  the  observations  made  on  earth- 
quakes in  the  various  coimtries  of  the  world,  whether  these  phenomena 
*  Otto  Volger,  Erdbeben  in  der  Srhweiz.  t  Ibid. 


506 


THE  EARTH. 


Fig.  210.  Area  over  which  was  felt  the  Explouion  of  Gunpowder  at  Mentz. 

are  produced  with  oi-  without  the  intervention  of  man,  will  some  day  en- 
able us  to  estimate  approximately  the  force  that  is  necessary  for  shaking 
some  given  area  of  the  earth's  surface.  These  would  be  comparative 
studies  which  could  be  made  without  prejudice  in  favor  of  the  hypoth- 
esis of  the  central  fire  or  any  other  theory. 


ORE  AT  CATASTMOPHEH.  507 


CHAPTER  LXXV. 

GREAT  CATASTROPHES. — EARTHQUAKE   AT  LISBON. — AREA   OP  DISTURBANCE. 
— EARTHQUAKES   AT   SEA. 

As  a  natural  consequence  of  the  fellow-feeling  which  tends  to  unite  all 
men  together,  writers  of  tlie  earth's  history  have  been  prone  to  give  to 
earthquakes  a  geological  importance  bearing  a  proportion  to  the  number 
of  persons  overwhelmed  and  the  quantity  of  the  productions  of  human 
labor  destroyed.  A  shock  which  shakes  a  vast  city  filled  with  stone 
buildings,  in  which  thousands  of  individuals  are  assembled,  may  cause  the 
most  terrible  disasters,  while  a  much  more  violent  one  felt  by  the  inhab- 
itants of  a  nearly  desert  country  is  soon  forgotten  and  passed  over  by 
history.  According  to  Otto  Volger,  the  earthquake  at  Lisbon  was  scarce- 
ly more  violent  than  was  that  of  the  valley  of  Viege,  a  hundred  years 
after  (?) ;  but  it  remains  memorable  on  account  of  the  thousands  of  human 
beings  who  perished  in  it,  while  the  shock  of  Viege,  which  only  killed  two 
poor  mountaineers,  was  soon  forgotten. 

The  sudden  vibrations  ^Aich  overturn  cities  in  a  few  seconds  are,  in 
fact,  the  most  frightful  catastrophes  that  can  be  imagined  by  man.  All 
other  disasters  are  announced  by  some  precursory  signs.  The  stream  is- 
suing from  the  volcano  advances  but  slowly,  and  its  progress  across  viU 
lages  and  cultivated  land  may  be  foreseen.  The  floods  of  rivers  threaten 
the  embankments  long  before  they  break  through  them,  and  preparation 
may  generally  be  made  for  the  irruption  of  water.  Even  the  hurricane  is 
preceded  by  atmospheric  signs ;  but  earthquakes  generally  happen  sud- 
denly and  unexpectedly,  and  in  an  instant,  without  a  single  sign  to  ex- 
plain the  catastrophe,  whole  cities  are  demolished,  and  the  inhabitants 
destroyed  by  thousands.  The  earthquake  of  San  Salvador  only  lasted 
ten  seconds,  and  this  space  of  time  was  sufficient  for  the  destruction  of 
the  town.  The  successive  vibrations  which  devastated  Calabria  in  1783 
were  felt  during  barely  two  minutes.  The  terrible  movements  of  the 
eai'th  which  destroyed  Lisbon  succeeded  each  other  during  the  space  of 
five  minutes ;  but  it  was  the  first  shock,  lasting  from  five  to  six  seconds, 
which  caused  the  greatest  damage.  The  inhabitants  sometimes  make  use 
of  the  brief  respite  given  them  by  the  intervals  between  the  great  shocks, 
not  in  taking  refuge  in  the  open  air,  but  in  increasing  still  more  their 
chances  of  death :  struck  with  ten-or,  they  rush  into  the  churches,  the 
roofs  of  which  fall  in  upon  them.  After  some  of  these  castastrophes  the 
corpses  may  be  counted  by  tens  of  thousands :  the  shocks  in  Sicily  in  1693, 
and  Calabria  in  1783,  must  have  caused  in  each  of  these  two  countries  the 
deatli  of  1 00,000  persons.    Lastly,  records  of  more  or  less  credibility  speak 


50S  THE  EARTH. 

of  earthquakes  in  Syria,  Japan,  and  the  Sunda  Archipelago,  which  resulted 
in  a  sudden  loss  of  life  still  more  considerable.  In  526,  more  than  200,000 
people  met  with  their  death  at  Antioch  and  the  adjacent  towns. 

These  undulations,  which  are  so  terrible  in  their  consequences,  are  sim- 
ultaneously felt  over  vast  areas.  Thus  the  commotion  which  destroyed 
Lisbon  on  the  1st  of  November,  1755,  and  demolished  the  greater  part  of 
Oporto  and  several  other  places  in  Portugal,  threw  part  of  the  walls  of 
Cadiz  into  the  moats,  and,  it  is  said,  on  the  testimony  of  the  Governor  of 
Gibraltar,  that  the  greater  part  of  the  towns  of  Morocco,  Tetuan,  Tangiers, 
Fez,  Mequinez,  and  even  the  capital  itself,  were  ^erthrown  by  the  earth- 
quake. Kant,  the  philosoj^ier,  and  Hoffmann,  who  were  the  historians  of 
the  earthquake  at  Lisbon,  mention  a  great  number  of  other  countries  in 
Europe,  Africa,  and  even  the  New  World,  which  must  have  participated 
in  the  violent  disturbance.  The  vibrations  extended  over  an  area  of 
15,400,000  square  miles;  that  is  to  say,  about  a  twelfth  part  of  the  terres- 
trial surface.  The  statements  upon  which  the  various  accounts  of  the 
catastrophe  are  founded  are  not  alwa5'^s  of  any  great  value ;  it  is  now 
proved  that  the  extent  of  the  area  over  which  the  undulations  of  the  earth 
were  felt  on  this  occasion  has  been  singularly  exaggerated.  In  the  whole 
of  Europe,  popular  imagination  Avas  so  struck  bj^this  event,  which,  in  the 
course  of  a  few  minutes,  and,  indeed,  on  a  day  of  festival,  destroyed  so 
many  thousands  of  persons  under  the  ruins  of  a  great  capital,  that  it  was 
naturally  led  to  look  upon  the  earthquak^^t  Lisbon  as  a  phenomenon 
without  parallel,  the  scene  of  which  was,  if  not  the  whole  world,  at  least  a 
great  part  of  the  terrestrial  surface.  All  the  oscillations  which  were  felt 
in  Europe,  either  on  the  same  day  or  about  the  same  time,  were  considered 
in  a  general  way  as  the  result  of  the  great  commotion  at  Lisbon ;  and 
gradually  a  sort  of  legend  was  established  attributing  to  the  same  cause 
a  considerable  number  of  geological  facts  of  an  undecided  date,  such  as 
the  downfall  of  rocks,  the  formation  of  lakes,  the  breaking  up  of  ice,  and 
changes  of  temperature  in  thermal  springs.  Thus  a  shock  which, "  by  a 
strange  chance,"  was  felt  at  Turin  alone  on  the  9th  of  November,  a  week 
after  the  catastrophe  at  Lisbon,  was  attributed  to  this  vast  disturbance. 
The  movements  of  the  soil  described  as  having  taken  place  at  New  York 
on  the  18th  of  November  are  also  reckoned  among  the  undulations  which 
were  then  spread  far  and  wide.  The  Lake  Ontario  was  also  added  to  the 
immense  area  of  disturbance,  because  stong  vibrations  agitated  its  shores 
during  the  month  of  October;  that  is  to  say,  before  the  day  of  the  disas- 
ter. As  a  matter  of  fact,  there  is  no  positive  proof  that  the  terrestrial 
wave  spread  farther  than  Morocco  on  the  south,  the  Castiles  on  the  east, 
or  in  a  northerly  direction  farther  than  Angouleme  and  Cognac*  This,' 
however,  constitutes  an  area  of  1118  miles  in  length;  and  if,  as  the  diame- 
ter of  the  area  of  disturbance,  the  same  distance  is  taken  in  the  direction 
from  east  to  west,  we  shall  find  that  the  area  of  the  earth  shaken  by  the 
great  terrestrial  wave  of  Lisbon  was  more  than  1,158,000  square  miles,  or 
*  Otto  Volger,  Erdbeben  in  der  Sckweiz,  vol.  i. 


EFFECTS  OF  EAJiTJIQUAKES. 


509 


about  six  times  the  size  of  France.  As  a  term  of  comparison,  we  will 
mention  the  earthquake  which  was  felt  in  France  on  the  morning  of  the 
14th  of  September,  1866,  the  undulations  of  which  were  propagated  to  the 
north  as  i'ar  as  Rouen,  and  to  the  south  as  far  as  Bordeaux.  The  area  of 
disturbance  of  this  shock  must  be  estimated  at  about  77,218  square  miles, 
or  the  fifteenth  part  of  the  surface  agitated  by  the  earthquake  at  Lisbon. 


Fig.  211.  Chart  of  the  Earthquake  of  the  14th  of  September,  1866. 


At  the  time  of  this  latter  event  there  was  one  fact  which  contributed 
much  to  extend  the  apparent  area  of  disturbance ;  this  was,  that  a  marine 
wave,  haiTnonizing  with  the  shock  of  the  earth,  was  spread  across  the  At- 
lantic in  all  directions.  But  the  water,  being  more  easily  moved  than  the 
soil,  necessarily  transmitted  the  wave  to  a  greater  distance  than  the  com- 
paratively rigid  beds  at  the  bottom  of  the  sea.  At  the  mouth  of  the  Ta- 
gus,  the  wall  of  water  formed  by  the  waves  rose,  it  is  said,  to  a  height  of 
nearly  56  feet;  then,  filling  up  all  the  estuary  that  extends  in  front  of  Lis- 
bon, swept  over  the  quays  of  the  city  and  rushed  among  the  houses.  At 
Cadiz  a  wave  of  nearly  equal  size  rushed  above  the  ramparts,  and  caused 
much  more  havoc  than  the  earthquake  itself.  On  the  coasts  of  Madeira 
and  of  Holland,  the  mouth  of  the  Elbe,  the  sea-shores  of  Denmark  and 


510  THE  EARTH. 

Norway,  and,  lastly,  the  whole  circumference  of  the  British  Isles,  the  sea 
felt  the  reaction  of  the  shock  communicated  to  the  waves  in  the  waters  off 
Lisbon,  and  its  level  underwent  rapid  fluctuations.  The  undulations  of 
the  wave,  variously  modified  by  currents  and  tides,  struck  even  upon  the 
shores  of  the  New  "World.  At  Barbadoes  and  Martinique,  where  the  flow 
of  the  tide  never  exceeds  28  inches,  the  wave  produced  by  the  transatlan- 
tic earthquake  attained  a  height  of  13, 16,  and  even  19  feet.  Thus  the  ma- 
rine wave  resulting  from  the  shock  was  carried  to  a  distance  of  nearly  3728 
miles  in  a  straight  line.  In  1854,  at  the  time  of  the  earthquake  of  Simoda, 
the  wave  which  reached  the  coast  of  California  had  traversed  2485  miles 
the  whole  width  of  the  Pacific  Ocean. 

When  violent  shocks  agitate  the  ground,  towns  situated  on  the  sea- 
shore have  often  suffered  much  more  from  the  sudden  irruf)tion  of  the  Ava- 
ter  than  from  the  shaking  of  the  earth  itself  When  the  waves  receive 
the  shock  from  the  neighboring  coasts,  or  else  when  the  centre  of  disturb- 
ance is  at  the  bottom  of  the  ocean,  the  masses  of  water  rise  to  a  formida- 
ble height,  and  dash  upon  the  shores  as  if  during  a  hurricane.  In  1783,  at 
the  time  when  the  shock  in  Calabria  overthrew  the  towns  and  villages  on 
the  main  land,  a  terrible  bore,  after  having  swept  away  at  once  2000  per- 
sons assembled  on  the  coast  of  Scylla,  rushed  into  the  port  of  Messina, 
sank  all  the  ships,  and  undermined  the  base  of  the  superb  row  of  palaces 
which  bordered  the  shore:  more  than  12,000  individuals  perished,  it  is 
said,  under  the  ruins.  On  the  7th  of  June,  1692,  at  the  time  of  the  earth- 
quake which  shook  Jamaica  and  the  neighboring  seas,  the  waves  rushed 
violently  upon  the  town  of  Port  Royal,  and  in  the  space  of  three  minutes 
covered  more  than  2500  houses  with  a  depth  of  33  feet  of  water.  The 
ships  were  thrown  in  every  direction  on  to  the  land,  and  the  frigate  Swan 
was  stranded  upon  the  roof  of  a  house.  In  like  manner,  according  to  the 
statement  of  Acosta,  the  terrible  wave  which  destroyed  Callao  in  the  year 
1586,  and  carried  a  great  ship  right  up  on  to  the  Lima  road  at  a  point  52 
feet  above  the  mean  level  of  the  sea,  must  have  been  altogether  89  feet  in 
height.  The  Japanese,  whose  islands  have  often  suffered  from  earthquakes 
and  sea-bores  caused  by  submarine  shocks,  say  that  these  frightful  phe- 
nomena are  caused  by  the  blows  of  the  tail  of  a  monster  striking  against 
the  shore.  Thus  the  Greeks  attributed  the  vibrations  of  the  soil  not  only 
to  Pluto,  the  "  shaker  of  the  world,"  but  also  to  Neptune,  the  "  agitator 
of  the  waves." 


EARTH -WAVSS.  511 


CHAPTER  LXXVL 

MOVEMENT    OF   TERRESTRIAL   WAVES. — ^VARIATIONS   CAUfeED    BY   THE    INE- 
QUALITY   OF  VERTICAL  OUTLINE    AND  THE    DIVERSITY  OF  ROCKS. AREAS 

OF    DISTURBANCE. — NOISE    OF   EARTHQUAKES. — FRIGHT   OF  MEN   AND  AN- 
IMALS. 

Whatever  may  be  the  nature  of  the  first  shock,  whether  it  proceed 
from  a  sudden  swelling  up  of  lava  or  vapor,  or  whether  it  be  caused  by 
the  falling  in  of  upper  strata  upon  the  subjacent  beds,  the  effects  produced 
will  always  be  the  same  as  regards  observers  who  are  above  the  central 
point  where  the  phenomenon  is  produced.  They  will  experience  a  shock 
tending  upward.  Even  when  falling  Avith  the  ground,  they  might  well 
fancy  themselves  raised,  like  the  aeronaut,  whose  balloon  is  falling  toward 
the  earth,  sees  the  country  mounting  up  toward  him.  Around  the  central 
point  of  disturbance,  where  the  shock  takes  place  in  all  its  violence,  and  is 
felt  vertically,  in  a  manner  more  or  less  irregular,  according  to  the  num- 
ber of  shocks,  the  movements  become  more  and  more  oblique,  and  are 
propagated  across  the  strata  of  the  earth  ilf  a  direction  which  ultimately 
becomes  perceptibly  horizontal.*  The  phenomenon  of  undulation  which 
is  produced  in  solid  rocks  is  perfectly  analogous  to  that  which  may  be  ob- 
served in  water  when  a  stone  falls  into  it :  a  series  of  concentric  waves  is 
formed  round  the  centre  of  the  shock,  and  gradually  disappears  in  the  dis- 
tance. 

Terrestrial  waves  which  are  formed  thus  are  very  long  and  very  flat,  on 
account  of  the  inflexible  nature  of  the  rocks  through  which  Ihe  movement 
is  transmitted.  There  does  not,  however,  exist  a  single  authentic  meas- 
urement from  which  the  dimensions  of  each  wave  may  be  deduced.  The 
observer  feels  them  pass  rapidly  under  his  feet  during  an  earthquake,  and 
is  often  able  to  notice  the  rocking  of  houses  and  towers,  as  well  as  the  to- 
and-fro  motion  of  church-bells ;  but  these  movements  are  much  more  mark- 
ed than  those  of  the  ground,  and  the  movements  of  the  earth  have  not 
been  clearly  distinguished  on  any  occasion. 

As  to  the  direction  followed  by  the  waves,  the  tendency  generally  dif- 
fers much,  owing  to  the  inequalities  in  the  relief  of  the  ground,  from  the 
regular  direction  it  would  otherwise  take.  This  direction  is  often  very 
difficult  to  discover,  owing  to  th^want  of  necessary  instruments,  and  all 
the  local  circumstances  which  may  modify  the  movement.  It  appears, 
however,  that  in  mountainous  countries,  like  Switzerland  and  the  Pyre- 
nees, the  great  undulations  are  propagated  in  the  direction  of  the  valleys. 
In  striking  against  the  tilted  strata  atthc  base  of  mountains,  the  corru- 


♦  Robert  Mallet,  Observation  ^^arthquake  Phenomena 


i^hc 


512 


THE  EARTH. 


gations  of  the  soil  act  like  the  waves  of  a  river  dashing  against  the  shores ; 
they  break  up,  and,  changing  their  course,  run  along  at  the  foot  of  the 
heights  in  the  same  direction  as  the  stream  of  the  valley.  After  this  first 
ruptui'e  in  its  movement,  the  undulation  is  communicated  to  the  rocky 
masses  of  the  mountain,  and  traverses  their  whole  thickness.  Beyond 
these  lofty  groups  which  disturb  the  movement,  without  always  opposing 
to  it  any  insurmountable  obstacle,  the  vibrations  corrugate  the  soil  of  the 


PPSSSC-— 


212.  Transmission  of  Earth- waves. 


plains  in  a  more  regular  way ;  but  the  intensity  weakens  proportionately 
to  the  square  of  the  distance,  and  finally  ceases  to  be  perceptible  to  man. 
It  must  also  be  remarked  that,  at  the  periphery  of  the  area  of  disturbance, 
the  various  shocks  are  generally  produced  at  longer  intervals  than  at  the 
centre  of  the  earthquake.  The  stronger  the  waves  are,  the  more  rapidly 
are  they  propagated,  and  thus  it  follows  that  betAveen  the  difierent  undu- 
lations, which  generally  becomi  weaker  and  weaker,  the  interval  always 
increa^s  with  the  distance.  In  the  centre  the  shocks  all  seem  to  blend 
together;  toward  the  circumference  they  succeed  each  other  like  waves 
of  slighty-agitated  water. 

Among  the  causes  which  contribute  to  disturb  the  regular  movement 
of  terrestrial  oscillations,  the  diversity  of  geological  formations  must  also 
be  reckoned.  The  swiftness  of  the  transmission  of  the  movement  varies 
considerably,  according  to  the  composition  of  the  rocks,  the  quantity  of 
water  they  contain,  and  the  hardness  and  elasticity  of  their  layers.  In 
order  to  explain  the  difierence  that  exists  between  the  various  strata  as 
I'egards  the  propagation  of  terrestrial  waves,  Mr.  Mallet  makes  a  striking 
comparison.  If  a  person  applies  his  ear  to  a  railway-rail  which  is  struck 
with  a  violent  blow  at  a  point  about  a  mile  away,  the  compact  iron  trans- 
mits to  him  nearly  instantaneously  the  wave  of  the  sound ;  immediately 
after,  the  observer  will  feel  the  undulation  which  is  transmitted  through 
the  soil  below  the  rail ;  then  he  will  hear  the  noise  transmitted  by  the  at- 
mospheric waves.  If  a  canal  flows  along  by  the  side  of  the  railroad,  a 
man  plunged  in  the  water  would  perceive  the  sensation  of  the  blow,  but 
not  at  the  same  time.  In  fact,  the  mean  swiftness  of  the  wave  is  1138  feet 
in  the  air,  4692  in  the  water,  and  about  11,040  in  a  bar  of  iron. 

It  is  a  long-established  fact  that,  during  earthquakes,  the  shocks  are  prop- 
agated much  more  easily  through  compact  rocks  than  through  formations 
interrupted  here  and  there  by  faul^^ssures,  caves,  and  soft  ground.  Mr. 
Mallet  has  proved  these  facts  J>y  <I^^P^  and  oft-repeated  experiments,  made 


EAJiTBWAV£S.  513 

not  far  from  the  town  of  Holyhead  in  Wales,  When  mines  of  powder 
were  exploded,  the  waves  of  disturbance,  which  were  the  more  rapid  as 
the  charge  was  stronger,  were  propagated  951  feet  a  second  in  wet  sand, 
1283  feet  in  a  rock  of  friable  granite,  and  1640  feet  in  a  compact  granite. 
Subsequently  Mr.  Mallet,  having  made  some  direct  observations  as  to  the 
speed  of  transmission  of  the  waves  during  the  earthquake  at  Calabria  in 
1857,  found  that  it  was  about  820  feet  a  second-  According  to  the  same 
geologist,  the  starting-point  of  the  shock  was  nearly  three  miles  below 
the  surface. 

Without  having  made  any  exact  investigations,  the  Hellenes  and  the 
Romans,  who  inhabited  a  soil  frequently  shaken  by  earthquakes,  had 
found  out  the  fact  that  caverns,  wells,  and  quarries  retarded  the  disturb- 
ance of  the  earth,  and  protected  the  edifices  built  in  their  neighborhood. 
The  town  of  Capua  was,  it  is  said,  saved  from  the  effects  of  the  earth- 
quakes to  a  much  greater  extent  than  the  adjacent  cities  on  account  of 
the  nufnerous  springs  in  its  gardens.  Vivenzio  also  asserts  that  in  build- 
ing the  Capitol  the  Romans  took  care  to  sink  several  wells  in  order  to 
weaken  the  effect  of  terrestrial  oscillations,  and  this  plan  succeeded  in 
preserving  the  building  from  all  damage.  In  like  manner,  the  great  con- 
structions at  Naples  were  built  above  vast  caves,  in  which  the  force  of  the 
subterranean  commotion  is  lost.  Humboldt  has  described  this  curious  fact 
— that  at  St.  Domingo  the  inhabitants  of  the  town  spontaneously  formed 
the  idea,  similar  to  that  of  the  Greek  and  Roman  naturalists,  of  digging 
out  deep  cavities  as  the  only  means  of  securing  the  stability  of  their 
dwellings. 

Besides,  as  may  readily  be  supposed,  the  longer,  thicker,  and  lower  the 
walls  of  the  edifices  are,  the  better  they  resist  the  shock.  In  all  towns 
partly  destroyed  by  earthquakes,  it  is  said  that  walls  of  this  form  were 
rarely  demolished.  When  the  undulations  of  the  soil  are  propagated 
along  the  whole  length  of  a  block  of  low  houses,  there  is  hardly  au  in- 
stance in  which  the  latter  have  been  shattered ;  in  countries,  therefore,  in 
which  the  movements  of  the  soil  generally  assume  the  same  direction,  dis- 
asters can  nearly  always  be  provided  against  by  setting  the  principal  walls 
of  the  edifice  in  the  direction  of  the  terrestrial  undulations. 

The  buildings  which  always  suffer  the  most  are  those  which  have  vault- 
ed roofs,  elevated  in  the  form  of  domes  or  cupolas.  The  thrusting  action 
of  the  heavy  masses  which  crown  the  edifice  causes  the  walls  to  separate 
when  they  are  in  a  state  of  vibration  from  the  effects  of  the  subterranean 
shocks ;  the  dome  falls  down  inside,  while  the  walls  give  way  in  an  out- 
ward direction.  A  considerable  area  is  covered  with  ruins  all  round  the 
piece  of  ground  on  which  the  foundations  stand,  and,  in  consequence,  the 
danger  of  ^ing  crushed  becomes  very  great  to  any  pefcons  who  are  near 
the  scene  flPthe  catastrophe.  It  was  the  earthquakes,  and  not  the  barba- 
rians, which,  according  to  .the  evidence  of  Mr.  Mallet,  destroyed  so  large  a 
number  of  the  palaces  and  temples  of  Rome  during  the  period  between 
the  fifth  and  ninth  centuries.     In  like  manner,  in  more  modern  times,  ca- 

Kk 


514 


THE  EARTH. 


thedrals  and  churches  have  often  been  overthrown,  while  other  houses 
were  saved.  This  well-known  fragility  of  vaulted  roofs,  when  shaken  by- 
undulations  of  the  soil,  will  explain  the  cause  of  those  frightful  calamities 
wliich  took  place  in  various  churches  at  the  time  of  the  earthquakes  of 
Lisbon,  Calabria,  Caraccas,  Mendoza,  and  San  Salvador,  when  kneeling 
multitudes  were  crushed  in  the  ruins. 

The  difference  presented  by  rocks,  as  regards  the  speed  with  which  the 
earthquake  wave  is  propagated  through  them,  and  the  various  obstacles 
which  impede  it,  has  the  effect  of  giving  to  the  areas  of  perceptible  dis- 
turbance shapes  which  are  perfectly  irregular.  The  movements,  there- 
fore, are  not  produced  round  the  initial  point  with  a  regularity  which  can 
be  at  all  compared  to  that  of  the  wavelets  which  surround  with  their  reg- 
ular circles  the  centre  of  a'^itation  in  a  disturbed  water.  Some  earth- 
quakes, as  far,  at  least,  as  it  is  possible  to  judge  from  incomplete  observa- 
tions, seem  to  be  propagated  in  very  elongated  ellipses.  Others  appear 
to  have  had  for  their  area  a  space  of  a  polygonal  shape;  thus  the  great 
paroxysm  of  the  valley  of  Viege,  which  extended  over  108,878  square 
miles,  was  felt  three  times  farther  in  a  northern  than  in  a  southern  di- 


Fig.  213.  Area  affected  by  the  Earthquake  of  Viege  in  1S55. 


• 


EAJRTSWAVES.  515 

rection.  Sometimes,  outside  the  limits  of  the  ground  in  a  state  of  vibra- 
tion^  a  region  has  been  remarked  which  likewise  shakes,  like  a  kind  of 
trembling  islet  surrounded  by  immovable  land.  At  other  times  vast 
tracts  have  not  experienced  any  apparent  disturbance,  while  the  ground 
all  round  them  was  trembling^  On  the  25th  of  July,  1846,  the  shock  of 
which  the  severest  impulse  was  felt  below  St.  Goar,.on  the  banks  of  the 
Rhine,  propagated  its  undulations  in  France  and  Germany  over  a  surface 
estimated  at  24,207  square  miles;  but  a  belt  about  100  yards  wide,  be- 
tween Pyrmont  (Westphalia)  and  the  right  bank  of  the  Rhine,  appears  to 
have  remained  immovable.*  According  to  the  testimony  of  Humboldt, 
this  fact  of  rocks  not  participating  in  the  general  movement  of  the  sur- 
rounding formations  has  been  frequently  noted  at  the  time  of  earthquakes 
in  the  Andes.  The  natives  say  of  these  intermediate  zones,  thus  exempt- 
ed from  the  vibrations  of  the  ground  round  them,  that  they  form  a  bridge 
{hacen  puente)^  meaning  by  this  that  the  oscillations  are  transmitted  at  a 
great  depth  below  the  inactive  beds  at  the  surface.  It  is  difficult  to  im- 
agine how  such  phenomena  could  take  place  if  the  oscillations  of  the  soil 
were  caused  by  the  movement  of  the  waves  in  a  subterranean  sea  of  fire : 
if  it  were  so,  the  upheaved  terrestrial  crust  would  undulate  like  an  object 
floating  on  the  surface  of  the  water,  and  the  burning  waves,  spreading 
out  in  a  circle,  would  also  give  a  perfectly  round  periphery  to  the  super- 
ficial area  of  the  eaithquake. 

To  the  two  kinds  of  movement  whicl^ave  been  observed  in  earth- 
quakes—  the  upward  shock  and  the  long  undulations  spreading  in  the 
manner  of  marine  waves — most  of  the  savants  since  Aristotle  also  add  the 
rotating  or  gyratory  movement  {vorticosum).  The  fact  is,  that  in  great 
cataclysms,  when  the  difierent  shocks  cross  each  other  in  the  ground,  it 
has  been  thought  that  proofs  of  these  twisting  movements  have  been  felt 
and  even  seen.  At  Quintero,  in  Chili,  three  great  palm-trees,  says  Hum- 
boldt, twisted  round  one  another  like  willow-wands,  after  each  had  swept 
a  small  space  round  its  trunk.  Otto  Volger,  who  does  not  believe  in  the 
existence  of  rotatory  movements,  mentions,  however,  the  example  of  the 
steeple  of  Grajchen,  which,  twisted  during  the  earthquake  in  the  valley  of 
Vi^'ge  in  1856 :  it  is  true  that  this  twisting  may  have  been  caused  either 
by  a  movement  of  the  soil  being  communicated  to  the  edifice,  or  by  the 
want  of  equilibrium  between  the  different  parts  of  the  steeple.  Mr.  Mal- 
let also  explains,  by  a  difference  between  the  centre  of  form  and  the  cen- 
tre of  gravity,  the  gyratory  movement  which  the  stones  of  two  small  ob- 
elisks underwent  during  the  earthquake  at  Calabria  in  1V83 ;  he  absolute- 
ly denies  that  the  rotatory  movement  of  the  earth  could  take  place,  as  the 
Italian  naturalists  had  alleged. 

As  to  the  speed  of  the  propagation  of  terrestrial  waves,  it  was,  even 
recently,  very  difficult  to  estimate,  owing  to  the  want  of  precision  in  the 
transmission  of  intelligence  and  the  irregularity  of  the  clocks  in  the  dif- 
ferent cities.  Since  1853,  the  period  at  which  the  electric  telegraph  was 
*  Daabr^,  Cotnptes  Rendus,  1847. 


516  THE  EARTH. 

applied  for  the  first  time  in  describing  the  shocks  of  the  earthquake  of 
Soleure,  almost  certain  means  are  at  our  disposal  for  noting  the  passage 
of  terrestrial  waves  in  different  localities ;  but  up  to  our  time  it  has 
scarcely  been  employed  save  in  an  exceptional  way,  and  too  often  some 
of  the  desirable  conditions  of  exactitude  have  been  neglected. 

The  incomplete  information  gathered  by  Otto  Volger  about  the  great 
earthquake  of  Viege  in  1855  has  warranted  him  in  fixing  approximately 
the  speed  of  the  undulation ;  it  was  at  the  rate  of  2861  feet  a  second  from 
the  centre  of  vibration  as  far  as  Strasbourg,  and  1398  feet  only  in  the  di- 
rection of  Turin.  Robert  Mallet,  after  having  made  his  celebrated  exper- 
iments on  the  speed  of  transmission  of  shocks  in  the  rocks  at  Holyhead, 
instituted  compai'ative  investigations  into  the  speed  of  the  undulations  of 
the  great  earthquake  at  Calabria  in  December,  1857,  and  found  the  aver- 
age rate  774  feet  a  second.  Since  that  time  English  observers  established 
at  Travancore,  in  the  south  of  Hindostan,  have  estimated  the  movement 
of  the  undulations  of  a  local  shock  at  about  656  feet.  The  result  of  the 
calculations  varying  thus  in  proportion  of  one  to  four,  it  is  impossible  to 
indicate  any  average  figure  for  the  rate  of  transmission  of  terrestrial 
waves ;  it  is  certain  that  the  rapidity,  as  well  as  the  force  and  direction 
of  the  movement,  differs  according  to  the  nature  of  the  rocks,  and  the  po- 
sition of  the  chains  of  mountains  and  valleys. 

The  noises  which  are  heard  during  earthquakes  differ  in  intensity  still 
more  than  the  other  phenom^a,  and  are  much  more  difficult  to  classify, 
owing  to  the  deep  sensation  that  is  felt  w'hen  the  earth  is  heard  to  roar, 
and  the  part  which  the  imagination  never  fails  to  play  when  memory 
seeks  to  recall  tne  past.  The  sounds,  besides,  heard  at  the  time  of  the  sub- 
terranean downfall  sometimes  exceed  in  their  violence  all  known  noises, 
and  it  is  in  vain  to  seek  for  suitable  terms  in  which  to  describe  them.  In 
a  general  way,  the  noises  of  earthquakes  may  be  compared  to  explosions 
of  mines,  discharges  of  artillery,  peals  of  thunder,  the  rolling  of  carriages, 
the  fall  of  avalanches,  or  the  roar  of  cataracts.  The  diversity  of  these 
noises  is  explained  by  the  difference  of  the  phenomena  which  may  be  tak- 
ing place  in  the  interior  of  the  earth — the  falling  in  and  reboundings  of 
rocks,  the  overflow  of  subterranean  water,  the  irruption  of  masses  of  air 
through  fissures,  and  distant  echoes  reverberating  far  and  wide  in  the 
abysses.  It  is  a  strange  thing  that  sometimes  during  one  and  the  same 
earthquake  certain  persons  can  not  find  terms  strong  enough  to  express 
the  frightful  noises  that  they  have  heard,  while  others  think  they  have 
only  felt  the  shock  unaccompanied  by  the  least  sound.  According  to  M. 
Otto  Volger,  this  singular  difference  of  sensation  proceeds  from  the  fact, 
w'ell  known  to  natural  philosophers,  that  the  scale  of  sounds  perceived  by 
the  ear  differs  in  different  individuals;  just  as  in  a  meadow  some  persons 
do  not  hear  the  cry  of  the  cricket — the  note  is  too  shrill  for  them,  so, 
when  the  ground  is  shaken,  those  who  are  shaken  with  it  would  not  all  be 
able  to  hear  the  sounds  produced  by  the  cataclysm  on  account  of  nothing 
but  the  deepness  of  their  tone ;  the  noises  would  be  too  deep  for  their 


TERROR  CAUSED  BY  EARTBQVAEES.  517 

ears.  At  a  distance  from  the  centre  of  the  shock  the  noise  gradually  di- 
minishes in  intensity,  but  it  always  remains  difficult  to  distinguish  clearly, 
because  the  sound  is  transmitted  with  unequal  speed  both  under  the 
ground  and  in  the  atmosphere.  Through  the  terrestrial  strata  the  noise 
of  the  paroxysm  travels  with  more  rapidity  than  the  shock  itself;  the 
shock  is  heard  before  it  is  felt ;  then,  when  the  wave  has  passed,  the  sound 
is  heard  anew,  being  transmitted  more  slowly  by  the  air.  This  inequality 
in  the  passage  of  the  fi|||nd  through  the  different  mediums  results  in  a 
great  confusion  of  roaring  and  rattling,  of  which  it  is  very  difficult  to  give 
any  just  account.  Observers  have  compared  the  noise  of  a  distant  earth- 
quake sometimes  to  the  rumbling  of  thunder,  sometimes  to  a  stormy  wind 
or  the  flapping  of  the  wings  of  a  large  bird,  and  sometimes  even  to  a  dis- 
charge of  musketry,  the  crackling  of  fire,  or  the  whistle  of  a  locomotive. 
One  might  fancy  that  in  this  manifestation  of  its  mighty  vitality  nature 
makes  use  of  all  the  sounds  known  to  the  human  ear. 

All  this  diversified  uproar  and  these  frightful  noises  sufficiently  explain 
the  instinctive  terror  which  takes  possession  of  nearly  every  one  during 
^the  time  of  an  earthquake,  even  when  the  shocks  have  not  caused  any  fatal 
consequences.  Nevertheless,  as  Humboldt  remarks,  a  feeling  of  insecurity 
is  the  cause  which  generally  most  contributes  to  upsetting  moral  force. 
The  earth  which  wo  felt  so  firm  under  our  feet  becomes  as  fluctuating  as 
the  waves;  one  hardly  dares  to  walk  a  step  for  fear  of  being  swallowed 
up  in  the  opening  ground.  All  our  ideas  as  to  the  nature  of  things  be- 
come confounded,  and,  by  a  sudden  reaction  of  his  physical  or  his  moral 
nature,  the  man  who  feels  that  he  is  being  deprived  of  the  earth  he  stands 
on  loses  all  confidence  in  his  own  personal  powers. 

It  is  a  widely-spread  opinion,  which,  however,  is  not  as  yet  undeniably 
confirmed,  that  animals  manifest  the  greatest  uneasiness  at  the  approach 
of  an  earthquake.  In  certain  countries,  indeed,  where  these  convulsions 
of  the  ground  frequently  take  place,  cai'e  is  taken  to  observe  attentively 
the  ways  of  domestic  animals,  in  order  to  detect  the  presentiment  of  the 
coming  shock  and  to  prepare  for  the  danger.  It  may  perhaps  be  the  case 
that  slight  vibrations,  perceptible  only  to  the  delicate  senses  of  animals, 
precede  the  subterranean  downfalls;  but  very  often  it  is  probable  that 
remarks  of  this  kind  are  made  after  the  catastrophe,  and  that  imagination, 
excited  by  the  fright,  plays  no  inconsiderable  part  in  th6  descriptions. 
Be  this  as  It  may,  it  is  said  that,  before  an  earthquake,  rats,  mice,  moles, 
lizards,  and  serpents  frequently  come  out  of  their  holes,  and  hasten  hither 
and  thither  as  if  smitten  with  terror.  Even  the  crocodiles  have  fled  away 
from  their  marshes  and  hurried  toward  ten'a  firma^  roaring  with  fear.* 
At  Naples  it  is  said  that  the  ants  q\iitted  their  underground  passages 
smne  hours  before  the  earthquake  of  July  26, 1805,  and  that  the  grasshop- 
pers crossed  the  town  in  order  to  reach  the  coast ;  also  that  the  fish  ap- 
proached the  shore  in  shoals.f  A  fact  which  is  better  attested  is  the  fright 
of  animals  during  the  catastrophe  itself.  At  the  time  of  the  earthquake 
*  Humboldt,  Relation  Htstorique,  voL  v.       t  Landgrebe,  Natwrgeschichte  der  VuUcane,  vol.  ii. 


518  THE  EARTH. 

which  shook  the  valley  of  Viege  in  1855,. the  wild  birds  which  most  dread 
the  fowler,  such  as  owls,  woodpeckers,  and  peewits,  collected  on  the  trees 
close  to  the  dwelling-houses,  and  uttered  plaintive  cries,  as  if  to  demand 
the  succor  of  man.  Birds  of  long  flight — swallows  and  others — at  once 
took  wing,  and  flew  away  t»  distant  parts.  For  several  days,  also,  the 
frogs  ceased  their  croaking.* 

*  Otto  Volger,  Erdbehen  in  der  Schweij^vol.  iii. 


SECONDARY  EFFECTS  OF  SHOCKS,    *  5^9 


CHAPTER  LXXVn. 

SECONDARY  EFFECTS   OF   SHOCKS. — SPRIXGS. — JETS   OF  GAS. — FISSURES. — 
DEPRESSIONS   AND   ELEVATIONS,  OF   THE    GROUND. 

Earthquakes  very  frequently  exercise  a  considerable  influence  on  the 
discharge  of  springs  rising  to  the  surface  of  the  ground.  A  great  many 
instances  have  been  brought  forward  of  springs,  both  thermal  and  cold, 
whicli  have  suddenly  dried  up  or  have  increased  in  volume,  accompanied 
by  either  an  augmentation  or  diminution  of  temperature.  These  phenom- 
ena can  be  easily  understood.  After  each  downfall  of  rocks  or  fracture 
of  the  ground,  the  conduits  through  which  the  subterranean  rivulets  flow 
may  be  either  altogether  or  partially  obstructed ;  the  water  must  then 
seek  some  other  course,  or  must  flow  in  a  diminished  stream  through  the 
old  channel.  Sometimes,  also,  the  breaking  down  of  some  barrier  which 
penned  back  the  subterranean  water  opens  up  a  free  passage  to  it,  and  the 
spring  is  thus  augmented  in  its  discharge.  Again,  the  waters  of  several 
subterranean  currents  of  various  temperatures  may  become  mingled  in 
consequence  of  some  catastrophe,  and  the  springs,  therefore,  are  rendered 
either  warmer  or  colder.  In  August,  1854,  on  the  occasion  of  a  violent 
earthquake  in  the  central  Pyrenees,  the  heat  of  a  spring  at  Bareges  was 
raised  from  64°  to  82°  (Fahr.),  and  its  discharge,  which  was  2.729  gallons 
a  day,  increased  to  6338  gallons. 

The  effect  more  generally  produced  on  springs  by  the  occurrence  of  an 
earthquake  is  to  render  the  water  muddy  by  filling  it  with  the  debris 
which  has  fallen  from  the  rocks  disturbed,  and  been  raised  by  the  ascend- 
ing body  of  water.  During  a  series  of  observations  made  on  the  artesian 
well  at  Passy  in  1861  and  1862,  M.  Herve-Mangon*ascertained  that  at  the 
time  of  each  of  the  subterranean  shocks  of  Western  Europe  which  were 
recorded  by  M.  Perrey  during  the  above-named  interval,  the  water  in  the 
well  w^  charged  with  sediment.  On  the  14th  of  November,  1861 — the 
day  on  which  a  great  earthquake  occurred  in  Switzerland — the  sediment 
in  the  well  at  Passy  suddenly  increased  in  quantity  from  956  grains  per 
cubic  metre  to  2268  grains;  the  next  day  it  decreased  to  1404  grains. 
This  skillfulchemist,  by  numerous  processes,  established  several  other  strik- 
mg  coincidences  between  the  impurity  of  the  water  and  the  vibrations  of 
the  ground.  It  is  not  at  all  probable  that  these  geological  facts  are  de- 
void of  any  mutual  relation  ;  it  appears,  on  the  contrary,  that  the  artesian 
spring  at  Passy,  and  doubtless  also  most  other  springs  gushing  out  to  the 
surface,  might  be  looked  upon  as  actual  "  seismometers."  At  the  time  of 
earthquake  shocks  a  kind  of  clearing  out  takes  place  of  the  natural  or  ar- 
tificial conduits  through  which  the  spring  water  passes.  According  to  the 
observations  of  M.  Fran9ois,  Avho  devoted  considerable  study  to  the  action 


520  *  ^^^  EAETH. 

of  earthquakes  on  the  mineral  springs  of  the  Pyrenees,  the  results  of  a 
shock  are  rarely  felt  for  any  length  of  time  ;  after  the  lapse  of  two  or  three 
days  the  eflfects  are  no  longer  perceptible. 

In  all  countries  frequently  affected  by  earthquakes,  the  inhabitants  nev- 
er fail  to  tell  numerous  stories  as  to  sudden  eruptions  of  water,  mud,  gas, 
or  flames.  Phenomena  of  this  kind  may  be,  in  fact,  produced  in  many  dis- 
tricts, for  shocks  violent  enough  to  close  up  or  to  enlarge  the  conduits  of 
springs  may  equally  well  open  out  fresh  channels,  and  thus  afford  an  out- 
let to  water  pent  up  under  deep  layers  of  rocks.  In  like  manner,  the  hy- 
drogen gases  which  are  formed  in  the  ground  by  the  decomposition  of  or- 
ganic matter  may  find  an  outlet  by  the  breaking  down  of  the  rocks  above 
them,  and  burn  spontaneously,  like  the  gases  at  Baku.  Nevertheless,  these 
curious  eruptions,  however  probable  they  may  appear,  have  not  as  yet 
been  scientifically  observed,  and  no  idea  seems  to  have  been  formed  as  to 
the  real  importance  they  might  have.  Even  Mr.  Mallet,  the  great  advo- 
cate of  the  constant  connection  between  earthquakes  and  volcanic  phe- 
nomena, has  not  ventured  to  look  upon  these  sudden  jets  of  water,  mud, 
and  gas  as  facts  on  which  science  may  depend.  With  regard  to  the  sud- 
den appearances  of  flashes  and  sparks,  these  may  be  explained  in  many 
cases  by  the  collision  of  stones,  which  strike  against  one  another  as  they 
fall. 

Occasionally,  during  earthquakes,  the  ground  is  rent  open  for  very  con- 
siderable distances.  In  1783,  at  the  time  of  the  terrible  shocks  which  dis- 
turbed Calabria,  the  phenomena  of  ruptures  of  the  ground  ranked  among 
the  grandest  and  most  frightful  effects  of  the  catastrophe.  Whole  moun- 
tain-sides, undermined  by  water,  slid  down  e7i  masse,  and  tumbled  into  the 
plains  below,  covering  all  the  cultivated  ground.  Cliffs  fell  down  in  a 
body,  and  rocks  opened,  swallowing  up  the  houses  which  stood  upon  them. 
At  the  western  base  of  the  granitic  chain  of  the  peninsula,  the  ground  af- 
fected by  the  shock  was  cleft  open  for  a  length  of  more  than  1 8  miles,  and 
in  some  places,  especially  near  Polistena,  the  fissure  was  several  yards  in 
width.  Elsewhere  other  clefts  were  opened,  one  of  which,  near  Cergulli, 
was  no  less  than  131  feet  in  depth  for  a  length  of  more  than  a  mile,  and 
32  feet  wide.  In  the  environs  of  Rosarno,  on  the  shore  of  the  Guy  of  Ni- 
cotera,  well-like  cavities  were  hollowed  out  with  circular  margins,  doubt- 
less caused  by  the  gushing  out  of  springs.  Finally,  districts  with  a  level 
surface  were  cleft  in  every  direction  by  cracks  radiating  in  the  shape  of  a 
star ;  the  ground  was  broken  up  in  a  similar  manner  to  mud  which  has 
cracked  from  the  loss  of  its  moisture.  In  February,  1835,  on  the  occasion 
of  the  earthquake  at  Conception,  in  Chili,  similar  phenomena  were  ob- 
served :  every  where,  says  Fitzroy,  contact  ceased  between  the  shifting 
ground  of  the  plain  and  the  bases  of  the  rocky  hills.' 

Not  only  do  fissures  sometimes  form  in  the  ground  during  earthquakes, 
but  after  commotions  of  this  kind  the  level  of  the  terrestrial  surface  is  oc- 
casionally permanently  changed.  When  the  catastrophe  is  caused  by 
some  subterranean  downfall,  it  is  perfectly  natural  that  the  surface  layers, 


EFFECTS  OF  EASTHQITAKES. 


521 


being  suddenly  deprived  of  their  supports,  should  be  included  in  the  sub- 
sidence ;  and,  in  fact,  several  instances  have  been  brought  forward  of  these 
sinkings  in  the  level  of  the  ground.  In  some  countries  it  is  said  that  phe- 
nomena of  a  directly  opposite  class  have  been  observed,  and  whole  dis- 
tricts have  been  suddenly  upheaved  a  few  inches,  or  even  several  feet.  If 
the  facts  are  certain  (and  there  seems  but  little  doubt  about  them),  they 
would  go  to  prove  that  earthquakes,  from  which  these  upheavals  result, 
are  caused  by  the  pressure  of  confined  vapor. 

Among  shocks  of  this  kind  we  must  mention  the  great  geological  catas- 
trophe, unfortunately  but  too  well  known,  which,  in  the  year  1819,  changed 
the  shape  of  the  country  of  Cutch  over  a  vast  area.  A  part  of  the  Great 
Runn  sank  down  over  an  extent  of  some  thousands  of  square  miles,  and, 
in  consequence  of  the  inroads  of  the  salt  water,  it  became  a  tract  of  land 
of  an  undetermined  character — during  drought  a  desert  without  water, 
and  during  the  monsoons  a  salt  lagoon.  A  rampart  several  miles  in  length, 
164  feet  broad,  and  9  feet  in  height,  was  also  raised  in  a  straight  line  across 
one  of  the  former  mouths  of  the  Indus.  This  rampart  is  called  by  the  in- 
habitants of  the  adjacent  districts  "God's  wall"  {UUah  Uraul),  to  distin- 
guish it  from  the  Ally  and  Mora  barriers,  which  the  sovereigns  of  the  coun- 
try had  constructed  farther  up  stream.  According  to  Mr.  A.  Barnes,  the 
earthquake  which  produced  this  strange  phenomenon  of  elevation  and  de- 
pression was  felt  over  an  area  of  more  than  95,500  square  miles. 


Mora  Bund] 


\''^^-'=^?i^^^^^\^m 


Fig.  214.  Tliti  Uann  of  Catch  and  the  Ullah  Band. 


With  regard  to  the  earthquake  at  Conception  in  1835,  the  affirmative 
evidence  on  the  point  is  so  abundant,  that  the  raising  of  the  coast  at  this 


522  ^^^  EARTH. 

place  must  be  regarded  as  a  positive  fact  ;*  but  it  must  remain  unknown 
whether  some  enormous  depression  in  the  interior  of  the  continent  did 
not  compensate  for  the  temporary  upheaval  of  the  sea-coast.  Still  more 
recently,  on  the  23d  of  January,  1855,  at  the  time  of  an  earthquake  which 
violently  shook  New  Zealand,  and  especially  the  two  shores  of  Cook's 
Straits,  the  ground  on  which  the  town  of  Wellington  stands  was  raised 
23  inches,  a  cape  in  the  vicinity  was  elevated  nearly  10  feet,  while  a  fis- 
sure of  about  40  miles  in  length  opened  in  the  southern  island  on  the  oth- 
er side  of  the  straits,  and  the  alluvial  plain  of  a  small  stream  sank  consid- 
erably.! Also,  in  1861,  the  coast  of  Torre  del  Greco,  at  the  foot  of  Vesu- 
vius, was  suddenly  raised  Z^  feet  for  a  length  of  more  than  a  mile.  All 
these  are  extraordinary  phenomena,  and  a  just  hesitation  must  at  present 
be  felt  in  venturing  to  give  any  explanation  of  them. 

There  is  another  geological  fact  which  has  been  little  studied  as  yet, 
which,  however,  must  be  perhaps  attributed  to  oscillations  of  the  ground : 
this  is  the  cuiious  arrangement  that  is  assumed  in  some  plains  by  the  boul- 
ders, pebbles,  and  drifts  of  sand.  Thus,  in  the  Desert  of  Atacama,  in  many 
spots  regular  figures  are  to  be  met  with — circles,  squares,  or  lozenges — 
composed  of  small  fragments  of  quai-tz  or  other  stone.J  In  the  entirely 
uninhabited  plains  of  Safa,  at  the  foot  of  the  former  volcanoes  of  Djebel- 
Hauran,  M.  Wetzstein  likewise  remarked  a  multitude  of  small  figures 
with  regular  angles,  formed  something  like  mosaics,  over  very  considera- 
ble areas.*  Must  we  look  upon  these  designs  as  some  immense  symbolical 
work  to  be  attributed  to  the  ancient  inhabitants  of  the  district,  or  are 
they,  in  fact,  the  sports  of  nature,  and  phenomena  similar  in  character  to 
the  figures  shaped  out  by  grains  of  sand  agitated  on  vibrating  plates  ? 
This  question  remains  to  be  solved  by  future  observers. 

*  Vide  below,  p.  529.  t  F.  von  Hochstetter,  Neu  Seeland. 

X  Techndi,  JErganzungshe/i  ;  Mittheilungen  von  Petermann,  1860. 


PERIODICITY  OF  EAKTUqUAKES. 


523 


CHAPTER  LXXVm. 

PERIODICITY  OP  EARTHQUAKES. — THE  MAXIMUM  IN  WINTER. — THE  MAX- 
IMUM AT  NIGHT.  —  COINCIDENCE  WITH  HURRICANES.  —  INFLUENCE  OP 
THE    HEAVENLY   BODIES. 

From  time  immemorial  it  has  been  asserted  by  the  natives  of  the  coun- 
tries which  are  most  frequently  ravaged  by  earthquakes,  that  these  com- 
motions bear  some  intimate  relation  to  the  movements  of  the  atmosphere, 
and  very  generally  coincide  with  certain  uicteorological  conditions,  such 
as  rainy  seasons,  numerous  storms,  warm  and  damp  winds.*  Neverthe- 
less, most  geologists,  considering  these  oscillations  of  the  ground  to  be 
nothing  more  than  the  half-exhausted  quiverings  of  a  great  ocean  of  fire, 
have  even  recently  denied  the  possibility  of  any  such  coincidence. 

In  1834,  Professor  Merian,  having  classed,  according  to  their  appearance 
in  the  various  seasons  of  the  year,  118  earthquakes  which  occurred  at  Basle 
and  in  the  countries  round  it,  ascertained,  to  the  surprise  of  the  scientific 
world,  that  these  phenomena  are  much  more  frequent  in  winter  than  in 
summer.  This  fact,  which  was  at  first  called  in  question,  has  since  been 
indubitably  established  by  the  investigations  of  Alexis  Perrey  and  Otto 
Volger.  Only,  in  proportion  as  the  list  of  shocks  becomes  more  numer- 
ous, the  difierence  between  the  winter  maximum  and  the  summer  max- 
imum tends  to  disappear,  for  the  simple  reason  that,  in  the  two  opposite 
hemispheres,  the  seasons  follow  one  another  at  six  months'  intervals,  and 
that  the  various  phenomena  in  connection  with  the  seasons  are  thus 
brought  into  a  state  of  equilibrium  on  each  side  of  the  equator.  It  is 
therefore  necessary  to  study,  in  each  region  separately,  the  order  in  which 
the  occun-ence  of  earthquakes  is  divided  among  the  diflferent  seasons.  The 
comparative  frequency  of  these  phenomena  during  the  winter  season  is 


Fig.  216.  Hontbly  Distribution  of  66C  Earthqoakes  in  France. 


Nambers.^  w 

Jan.     Feb.    March.  April.   May.    June.    July.     Aug.     Sept. 

then  much  more  easy  to  be  observed.    Thus  the  656  shocks  enumerated 
in  France  by  Alexis  Perrey  up  to  the  year  1845  are  divided  in  the  pro- 
portion of  3  to  2  respectively,  for  the  half  years  commencing  in  Novem- 
*  Luigi  Greco ;  Ferdinand  de  Luca ;  Alexis  Perrey. 


524 


THE  EARTH. 


ber  and  May.  In  the  regions  of  the  Alps,  where  there  are  no  volcanoes, 
the  difference  between  the  number  of  earthquakes  in  winter  and  summer 
is,  on  the  other  hand,  enormous.  By  comparing  the  four  months  of  May, 
June,  July,  and  August,  with  December,  January,  February,  and  March, 
we  see  that  the  shocks  are  three  times  as  numerous  in  the  second  season 
as  in  the  first.  In  Italy,  according  to  the  same  author,  the  difference  was 
much  less  perceptible,  since  out  of  984  earthquakes,  453  took  place  in  the 
summer  season,  from  April  to  September,  and  531  during  the  winter  half 

Fig.  216.  Monthly  Distribation  of  1230  Earthqaakes  in  Switzerland. 


Numbers. 


Jan.     Feb.    March.  April.  May.    June.    July.     Aug.     Sept.     Oct.     Nov.     Dec. 


year,  from  October  to  March.  Nevertheless,  even  in  this  region,  where 
most  of  the  great  subterranean  movements  are  evidently  in  connection 
with  volcanic  action,  these  phenomena  are  perceptibly  more  frequent  dur- 
ing the  cold  portion  of  the  year. 

If  we  limit  ourselves  to  the  study  of  some  particular  centre  of  shocks, 
the  difference  observed  between  the  seasons  in  respect  to  the  frequency 
of  subterranean  shocks  is  still  more  considerable.  As  an  instance  of  this 
we  may  mention,  on  the  authority  of  Otto  Volger,  the  remarkable  region 
of  the  Mid-Valais,  where,  out  of  a  total  number  of  98  known  earthquakes, 
one  only  took  place  in  summer,  while  V2  were  felt  in  winter.     The  pro- 


Fig.  217.  Monthly  Distribation  of  98  Earthquakes  in  the  Mid-Valais. 


^1     ->     I 


Kninbers.     3a    |     i6     |     4     |     o     |     o     |     o     |     i      |     «>    J      »      I     ^     I     ^     I     "^ 
Jan.      Feb.    March.  April.    May.    June.    July.     Aug.     Sept     Oct.      Nov.      Dec 


portion  is  nearly  the  same  in  the  region  of  Hohensax,  on  the  southern 
slopes  of  Santis,  not  far  from  the  former  fork  of  the  Rhine. 

Not  only  are  subterranean  commotions  more  frequent  in  winter  than 
in  summer,  at  least  in  the  regions  of  Central  Europe  and  on  the  coasts  of 


PERIODICITY  OF  EARTHQUAKES. 
Fig.  218.  Monthly  Distribntlon  of  98  Earthquakes  in  Southern  SSntis. 


525 


I      '      I     »     I      >     I     o    J     o     I     0     I 


J 


^ 


Nambere. 

Jan.      Feb.   March.  April.    May.    Jiinel    July.     Aug.     Sept.     Oct.      Nov.      Dec. 

the  3Iediterranean  as  far  as  Asia  Minor  and  the  Caucasus,*  but  this  re- 
markable fact  has  also  been  observed — that  the  shocks  are  felt  more  fre- 
quently at  night  than  in  the  day,  and  this  holds  good  in  all  seasons  of  the 
year.  In  all  earthquake  regions  this  is  uniformly  the  case.  In  Switzer- 
land, out  of  502  earthquakes,  the  date  and  time  of  which  are  known,  only 
182  took  place  between  six  o'clock  in  the  morning  and  six  o'clock  in  the 
evening ;  320 — that  is,  nearly  double — were  felt  during  the  twelve  hours 
of  the  night.  There  is,  therefore,  for  every  diurnal  period,  a  series  of  al- 
teniations  resembling  those  of  the  annual  period ;  but  there  is,  in  truth, 
Fig.  219.  Switzerland:  Dj^tribation  of  435  Earthquakes  every  other  Hoar. 


Numbers. 


Night.  Duy.  Night. 

no  reason  for  astonishment  in  this,  as,  in  an  entirely  general  point  of  view, 
every  day,  in  its  rain,  its  storms,  and  all  its  meteorological  phenomena, 
may  be  looked  upon  as  an  epitome  of  the  whole  year.  Looking  at  it  in  a 
certain  way,  midday  is  summer,  and  midnight  is  the  winter  of  each  diur- 
nal revolution.  Have  we  not,  then,  a  good  right  to  infer,  from  the  regu- 
lar fluctuation  of  subterranean  agitations,  these  fluctuations  correspond- 
ing with  the  lapse  of  seasons  and  hours,  that  these  great  events  depend, 
at  least  in  certain  countries,  on  some  external  phenomena,  and  not  on  the 
tremblings  of  a  sea  of  lava  ?  "  Are  they  not,"  as  Volger  says, "  connected 
with  the  whole  body  of  laws  which  govern  the  return  of  light  and  dark- 
ness, heat  and  cold,  snow  and  rain,  drought  and  running  water?"  The 
greater  number  of  earthquakes  would  thus  be  facts  essentially  connected 
with  the  conditions  of  climate.  .     . 

It  is  also  related  that,  during  the  hurricanes  in  the  West  Indies,  the 
ground  is  severely  shaken,  as  if  the  wind,  which  tears  down  trees,  over- 
throws buildings,  and  drives  the  waves  into  immense  water-spouts,  had 
also  laid  hold  of  the  layers  of  the  rocks,  and  had  shaken  them  on  their 
bases.  Is  it  the  fact  that  the  inhabitants,  under  the  influence  of  terror, 
fancy  that  the  ground  itself  participates  in  the  immense  convulsion  ? 
Such  hallucinations,  would  not  seem  very  wonderful  when  we  consider 
that  at  each  fresh  fury  of  the  cyclone,  nothing  but  death  is  expected. 
*  Moritz,  Bulletin  de  VAcadimie  St.  Petersbourg,  vol.  viji. 


526 


THE  EABTH. 
Fig.  220.  Monthly  Distribution  of  2249  Earttaqnakes  in  Europe. 


riCA 


kSOO 


LUM 


Numbers.  363      293      284       254       280       227       238      258       238      287       362       390 
Jan.    Feb.  March.  April.  May.  June.  July.  Aug.   Sept.    Oct.    Nov.    Dec 

Nevertheless,  the  evidence  relative  to  this  coincidence  between  hurri- 
canes and  earthquakes  is  so  abundant  and  positive,  that  it  is  diflBcult  not 
to  put  faith  in  it.  In  1844,  on  the  occasion  of  a  hurricane  which  de- 
stroyed hundreds  of  vessels  in  the  roads  of  Havana,  a  shock,  which  was 
not  connected  with  any  volcanic  phenomenon,  agitated  the  ground  of  the 
island.*  Still  more  recently,  during  the  cyclone  of  the  6th  of  September, 
1865,  which  ravaged  Guadaloupe,  the  Saintes,  and  Marie  -  Galante,  the 
earth  suddenly  shook  at  the  most  terrible  moment  of  the  tempest,  and 
several  houses  were  thrown  down.  What  is  the  cause  of  this  coincidence 
between  earthquakes  and  cyclones?  Does  the  electric  storm  itself  pene- 
trate into  the  depths  of  the  earth  ?  or  do  the  torrents  of  rain  produce 
subterranean  downfalls  ?  These  are  questions  to  which,  at  present,  it  is 
impossible  to  reply. 

However  this  may  be,  we  must  at  any  rate  admit  that  there  are  at  least 
two  classes  of  earthquakes ;  one  class  proceeding  from  the  pressure  and 
eruption  of  vapor  and  lava,  the  other  caused  by  the  downfall  of  rocks ; 
both,  however,  producing  the  same  impression  on  the  senses  of  man,  and 
developing  themselves  in  the  same  way  over  vast  areas.  Perhaps  to  these 
two  classes  of  shocks  it  may  be  necessary  to  add  a  third — those  shocks, 
namely,  which  originate  in  the  relations  existing  between  our  planets  and 
the  other  bodies  in  space.  Thus,  according  to  Wolf,  there  is  a  constant 
relation  between  earthquakes  and  the  spots  on  the  sun.  Finally,  the  in- 
vestigations carried  on  with  so  much  perseverance  by  Alexis  Perrey  prove 
unquestionably  that  the  successive  phases  of  the  moon  exercise  consider- 
able influence  on  movements  of  the  ground.  Like  the  ocean,  the  earth, 
too,  has  its  tides.  The  frequency  of  earthquakes,  even  of  those  which  are 
only  revealed  to  us  by  the  delicate  instruments  of  M.  d'Abbadie,  augments, 
like  the  height  of  the  flow  of  the  tide,  at  the  epoch  of  the  syzygies.  This 
frequency  increases  when  the  moon  approaches  the  earth,  and  diminishes 
when  it  is  farther  away ;  in  a  word,  the  time  when  the  sea  oscillates  with 
the  greatest  force  is  also  the  time  when  the  earth  itself  most  frequently- 
trembles.  "Our  planet,"  says  M.  Boscowitz, " is  engaged  in  a  constant 
exchange  of  forces  and  influences  with  the  heavenly  bodies,  which,  like  it, 
occupy  ethereal  space." 

.*  Andr^  Poey,  Comptes  Rendus  de  VAcad^mie  des  Sciences,  1866. 


UPHEAVALS  A 


V.  -"i.an  •  L'l 


Drawn  Lv  A  "^AiiUnmn   eflcr    Ch  Darwm 


HARPER  &  ER( 


DEPRESSIONS 


PLjgni 


T.^i^  b^    Erhird.li  K   Ia-^ij    Tmuin 


RS.  NEW  YORK 


OaCILLATIOyS  OP  TEE  GROUND.  527 


CHAPTER  LXXIX. 

SLOW  OSCILLATIONS  OF  THE  GROUND. — DIFFICULTIES  PRESENTED  IN  THE 
OBSERVATION  OF  THESE  PHENOMENA. — CAUSES  OF  ERROR:  EROSION  OF 
SHORES,  SWELLING  AND  SINKING  OF  PEATY  SOILS. — INFLUENCE  OF  TEM- 
PERATURE.— LOCAL   UPHEAVALS. 

The  solid  ground,  which  people  once  considered  as  the  symbol  of  im- 
mobility, is,  on  the  contrary,  in  a  state  of  constant  oscillation.  The  crust 
of  the  earth,  carved  out  incessantly  by  the  various  meteorological  agents 
on  one.  side,  drawn  by  the  other  bodies  revolving  in  space  on  the  other, 
modified  by  water  and  pressed  upon  by  vapors,  gases,  and  molten  matter, 
never  ceases  to  undulate  as  a  raft  rising  and  sinking  on  the  waves  of  the 
sea.  At  rare  intervals  there  are  great  earthquakes ;  more  often  this  un- 
dulation of  the  ground  consists  in  mere  vibrations,  which  are  scarcely  per- 
ceptible except  by  the  aid  of  instruments.  The  terrestrial  crust  is  not 
only  continually  shaken  by  these  transient  shiverings ;  it  is,  besides,  actu- 
ated by  uniform  movements  of  incalculable  force,  which  at  some  points 
raise  it,  and  at  others  depress  it,  as  compared  with  the  level  of  the  sea. 
While  we  are  busy  on  its  surface,  the  earth  itself  is  shifting  under  our 
feet. 

These  swellings  up  and  depressions,  which  recall  to  mind  the  phenom- 
ena of  organized  bodies,  often  take  place  so  slowly,  that  to  verify  them 
with  any  degree  of  certainty,  successive  generations  of  observers  would 
require  the  lapse  of  many  years,  or  even  centuries.  The  "patient  earth" 
seems  to  revolve  inertly  in  space,  and  yet  it  is  at  work  without  intermis- 
sion in  modifying  the  form  of  its  seas  and  its  coasts.  During  each  geo- 
logical period,  the  continental  surface,  motionless  in  appearance,  rises  in 
some  spots  to  a  great  height  above  the  ocean,  and  in  others  it  sinks  be- 
neath the  water ;  every  where,  indeed,  the  ancient  relief  and  outline  of  the 
ground  are  being  slowly  modified.  In  accordance  with  what  law,  in  what 
geographical  order,  and  at  what  comparative  rate  of  progress  do  these 
gradual  oscillations  take  place,  which  result,  in  the  long  run,  in  eflPbcting  a 
change  in  the  general  aspect  of  the  globe  ?  Science  is  not  as  yet  in  a  po- 
sition to  give  a  positive  answer  to  these  questions.  But,  in  the  mean 
time,  until  geologists  are  able  to  estimate  exactly  the  dimensions  and  prog- 
ress of  each  wave  of  upheaval  which  is  formed  by  the  crust  of  the  earth, 
it  is,  at  all  events,  possible  to  bring  together  the  principal  facts  which  bear 
upon  the  subject  of  the  oscillatory  movements  of  continents  and  the  bed 
of  the  sea. 

Small  broken  shells,  the  scattered  remains  of  polypes,  almost  invisible 
grooves  marked  here  and  there  on  the  sides  of  rocks — all  these  signs, 


528  ^^^  EARTH. 

which  most  jDeople  would  pass  'hj  with  indiiference,  are  become,  thanks  to 
the  patience  and  sagacity  of  observers,  so  many  undeniable  proofs  of  the 
regular  movements  of  the  ground.  It  is,  however,  only  on  the  sea-coast 
and  in  the  vicinity  of  seas  that  savants  can  positively  verify  these  mani- 
festations of  the  vitality  of  the  globe.  Considering  the  ocean  as  a  fixed 
level-mark,  which  is  almost  motionless  in  relation  to  the  elevated  or  de- 
pressed masses  of  the  land,  they  can  easily  prove  the  general  elevation  of 
a  region  by  noticing  on  the  shore  the  j)arallel  lines  formed  at  different 
epochs  by  the  friction  of  the  sea-water.  But  farther  inland  the  marks  of 
the  same  kind  which  are  traced  out  on  their  banks  by  rivers  and  lakes  are 
very  seldom  able  to  furnish  incontestable  evidence  of  vertical  oscillations 
of  the  soil.  The  more  or  less  shifting  level  of  lakes  and  running  water 
depends  on  several  geological  circumstances,  and  it  is  only  when  all  these 
circumstances  are  perfectly  well  known  that  the  ancient  terraces  and  slopes 
of  erosion  which  exist  in  fluvial  and  lacustrine  basins  can  be  made  to  serve 
as  marks  to  measure  the  progress  of  terrestrial  oscillations.  As  a  matter 
of  fact,  geologists  are,  therefore,  compelled  to  limit  themselves  to  bringing 
under  notice  those  oscillatory  movements  of  the  earth's  crust  which  are 
taking  place  on  sea-coasts. 

In  studying  the  oscillations  of  the  earth,  it  is  important  to  be  very  care- 
fully on  our  guai'd  against  the  numerous  causes  of  error  which  arise  from 
the  eternal  combat  which  is  always  taking  place  on  the  shore  between 
the  land  and  the  sea.  Neither  the  gradual  encroachments  of  a'lluvial 
shores,  nor  the  pi'ogressive  erosions  which,  in  so^many  places,  the  coast  has 
to  undergo  from  the  sea,  are  to  be  considered,  without  due  examination, 
as  proofs  of  the  upheaval  or  subsidence  of  a  region.  The  sand  which  is 
driven  up  by  the  waves  of  the  sea,  and  the  alluvium  which  is  drifted  down 
in  the  currents  of  rivers,  are  deposited  on  most  low  coasts  in  sufficiently 
considerable  quantities  for  the  belt  of  shore  to  increase  constantly  in 
breadth.  Even  where  this  zone  sinks  slowly  with  the  land  adjacent,  as  is 
taking  place  at  the  north  of  the  Adriatic,  the  alluvium  may  nevertheless 
form  on  the  shore  a  kind  of  cushion,  and  may  defend  the  plains  of  the  in- 
terior against  the  waves  of  the  sea.  On  the  other  hand,  there  are  a  great 
many  steep  beaches  and  cliffs  which,  being  assailed  in  front  by  the  waves 
and  the  tide,  and  worn  a^ay  obliquely  by  lateral  currents,  recede  gradu- 
ally before  the  inroads  of  the  sea ;  but  in  cases  of  this  kind  it  is  usually 
impossible  to  detect  the  slightest  depression  in  the  general  level  of  the 
country.  Gentle  geological  elevation  of  the  ground  may,  indeed,  actually 
coincide  with  a  falling  back  of  the  shores.  The  coasts  of  Aunis  and  Sain- 
tonge  present  an  example  of  this  apparent  anomaly. 

In  movements  of  the  soil  it  is  necessary  also  to  distinguish  those  which 
are  produced  by  the  slow  pressure  of  subterranean  forces,  and  those  which 
are  occasioned  by  temporary  causes,  such  as  the  more  or  less  quantity  of 
water  contained  in  the  surface  layers,  the  activity  of  evaporation,  and  the 
bringing  into  cultivation  of  the  country.  Thus,  when  peat-mosses  form  in 
the  low-lying  lands  of  the  valleys,  taking  the  place  of  lakes  and  marshes, 


LOCAL  OSCILLATIONS.  529 

they  hold  the  water  in  their  masses  of  moss  just  as  an  immense  sponge, 
and,  gradually  swelling,  ultimately  rise  to  a  height  of  several  feet  above 
the  former  level  of  the  soil.  On  the  other  hand,  those  tracts  of  peat-moss 
which  have  been  dried  by  draining  operations  gradually  sink ;  the  mosses 
wither,  die,  and  are  reduced  to  dust.  One  might  fancy  that  the  soil  was 
slowly  sucked  toward  the  interior  of  the  earth  by  some  secret  force. 

There  is,  however,  no  reason  to  be  astonished  at  these  alternate  phenom- 
ena of  swelling  and  shrinking  which  are  afforded  by  peaty  soil,  as  a  mere 
variation  of  temperature  is  sufficient  to  produce  similar  results  in  the  com- 
pact strata  of  mountains.  In  the  daytime  the  particles  of  rocks  dilate  un- 
der the  influence  of  the  solar  rays ;  in  the  night  time  they  become  cool, 
and  contract  in  consequence  of  radiation,  and  the  total  mass  sinks  to  a 
very  slight  extent,  which  is  sometimes  perceptible  by  means  of  instru- 
ments. Thus  Moesta,  the  Chilian  astronomer,  has  been  enabled  to  ascer- 
tain that  the  National  Observatory  of  Chili,  situated  on  the  hill  of  Santa 
Lucia,  near  Santiago,  rises  and  descends  alternately  in  the  space  of  twen- 
ty-four hours.  The  daily  oscillations  of  the  rock,  which  in  turn  dilates 
and  shrinks,  are,  indeed,  considerable  enough  to  render  it  necessary  to  in- 
troduce this  element  of  calculation  into  the  mathematical  formulaj  devot^^ 
to  the  regular  observations.  Similar  phenomena,  but  occasioned  by  diF 
ferent  causes,  are  produced  under  the  Observatory  of  Armagh,  in  Ireland. 
After  heavy  rains,  the  hill  on  which  the  edifice  stands  rises  perceptibly ; 
then,  after  active  evaporation  has  got  rid  of  the  extra  water  contained  in 
its  pores,  the  hill  again  sinks. 

The  shocks  of  greater  or  less  violence  communicated  to  the  soil  in  vol- 
canic districts  produce  alterations  in  the  level  which  are  much  more  con- 
siderable than  the  slight  oscillations  caused  by  the  heat  of  the  sun  or  the 
various  atmospheric  agents.  But  these  alterations  of  level  are  none  the 
less  merely  local  phenomena,  and  although  they  are  doubtless  connected 
with  the  same  class  of  facts  as  the  slow  upheavals  and  depressions,  they 
must  be  clearly  distinguished  from  the  long-protracted  movements  which 
bulge  up  the  crust  of  the  earth  under  whole  continents.  As  an  instance 
of  the  local  undulations  which  are  mere  accidents  in  the  history  of  the 
planet,  we  may  mention  that  which  the  earthquake  of  Conception  caused 
to  take  place  temporarily  in  February,  1835,  at  the  Isle  Santa  Maria  and 
the  adjacent  coasts  of  the  Chilian  main  land.  An  enoiinous  mass  of  earth 
♦  was  suddenly  elevated.  The  shore  nearest  the  town  was  raised  perpen- 
dicularly a  yard  and  a  half,  while  the  island,  uprooted,  so  to  speak,  by  the 
violence  of  the  subterranean  shock,  was  upheaved  obliquely  2^  yards  at  its 
southern  point,  and  3^  yards  at  its  northern  extremity.  Two  months  aft- 
erward the  shore  at  Conception  was  scarcely  23  inches  above  its  former 
level,  and  the  island  had  also  sunk  in  proportion.  Finally,  toward  the 
middle  of  the  year,  every  trace  of  the  upheaval  had  disappeared,  and  the 
sea-water  came  exactly  up  to  the  same  winding  line  of  debris  which  it 
washed  before  the  catastrophe.* 

*  Fitzroy,  Voyage  of  the  *^ Adventure"  and  the  '■^Beagle." 

Ll 


530  ^^^  EARTH. 

The  famous  columns  of  the  supposed  Temple  of  Serapis,  which  rise  on 
the  shore  of  the  Mediterranean,  not  far  from  Pozzuoli,  likewise  bear  on 
their  marble  shafts  proofs  of  purely  local  oscillations.  Spallanzani  some 
time  ago  showed  that  these  columns,  the  bases  of  which  were  surrounded 
with  rubbish,  must  at  some  former  date  have  been  immersed  in  the  water 
of  the  sea  to  a  depth  of  about  21  feet ;  for  up  to  this  height  the  calcareous 
cases  of  the  serpulae  may  be  noticed  on  the  shafts,  and  also  the  innumera- 
ble holes  that  the  pholades  have  hollowed  out  in  the  thickness  of  the  mai*- 
ble,  which  is  eaten  away  circularly  by  the  waves.  The  temple,  having 
been  repaired  in  the  reign  of  Marcus  Aurelius,  must  certainly,  at  that  time, 
have  been  above  the  level  of  the  sea.  It  is  not  known  at  what  date  it 
sank,  together  with  the  hillock  on  which  it  stands.  It  might,  perhaps, 
have  taken  place  during  the  year  1198,  in  which  year  the  Solfatara  of 
Pozzuoli  produced  an  eruption.  With  regard  to  the  emergence  of  the 
colonnade  from  the  water,  it  is  probable  that  it  happened  in  the  year  1538, 
at  the  time  when  the  Monte  Nuovo  made  its  appearance.  If  these  sup- 
posed dates  are  the  real  ones,  the  lower  half  of  the  Temple  of  Serapis  must 
have  been  bathed  for  340  years  in  the  waters  of  the  gulf  But  this  event 
^kn  only  have  been  caused  by  some  local  agitation  of  the  earth ;  for,  dur- 
ing the  same  period,  the  adjacent  coasts  of  Naples  have  not  altered  their 
level  to  any  perceptible  extent.* 

*  Lyell,  Principles  of  Geology,  vol.  i. 


UPHEAVAL  OF  SCANDINAVIA.  53X 


CHAPTER  LXXX. 

UPHEAVAL   OF  THE   SCANDINAVIAN  PENINSULA;   OP  SPITZBEEGEN ;   OP  THE 
COASTS   OP   SIBERIA;    OP   SCOTLAND;    OP  WALES. 

On  all  those  coasts  where  heaps  of  modern  shells  now  left  dry,  and  the 
ledges  cut  out  at  diflferent  heights  in  the  faces  of  the  cliffs,  furnish  un- 
questionable testimony  of  a  progressive  upheaval  of  the  ground,  savants 
who  desire  to  study  the  progress  of  the  phenomenon  must,  of  course,  do 
so  both  by  direct  measurements  and  by  comparing  the  levels  taken  at 
longer  or  shorter  intervals.  More  than  a  hundred  and  thirty  years  ago, 
Celsius,  the  Swedish  astronomer,  formed  the  idea  of  resorting  to  these 
means,  not  with  the  intention  of  verifying  the  growth  of  the  Scandinavian 
peninsula — a  fact  which  to  him  did  not  seem  at  all  probable — but  in  order 
to  prove  the  supposed  alteration  in  the  level  of  the  waters  of  the  Baltic 
Sea.  He  was  aware,  from  the  unanimous  testimony  of  the  inhabitants  of 
the  sea-coasts,  that  the  Gulf  of  Bothnia  was  constantly  diminishing  both 
in  depth  and  extent.  Old  men  pointed  out  to  him  various  points  on  the 
coast  over  which,  during  their  childhood,  the  sea  used  to  flow,  and,  be- 
sides, showed  him  the  water-lines  which  the  waves  had  once  traced  out 
farther  inland.  Added  to  this,  the  names  of  places,  the  position  more  or 
less  upon  the  main  land  of  former  ports  now  abandoned,  and  of  edifices 
built  once  upon  the  shore;  the  remains  of  boats  found  far  from  the  sea; 
lastly,  the  written  records  and  popular  songs,  could  leave  no  doubt  what- 
ever as  to  the  retreat  of  the  sea-water.  At  this  epoch,  when  savants  &i\\\ 
believed  in  the  immovable  solidity  of  the  rocky  frame- work  of  the  globe, 
Celsius  was  naturally  bound  to  attribute  the  constant  growth  of  the  sea- 
coast  to  the  gradual  depression  of  the  level  of  the  #ea.  In  1730  he  felt 
himself  waiTanted,  by  comparing  all  the  evidence  he  had  collected,  in  pro- 
pounding the  hypothesis  that  the  Baltic  sunk  about  3  feet  4  inches  every 
hundred  years.  Then,  in  the  course  of  the  following  yeai',  having,  in  com- 
pany with  Linnaeus,  made  a  mark  at  the  base  of  a  rock  in  the  island  of 
Xoeffgrund,  situated  not  far  from  Jefle,  he  was  able  personally  to  verify, 
thirteen  years  afterward,  that  the  retreat  of  the  Baltic  Sea  was  taking 
place  quite  as  rapidly  as  he  had  siipposed.  The  difference  of  level  ob- 
served during  these  thirteen  years  was  7  inches,  or  4  feet  5  inches  for  a 
century.  From  1730  to  1839  the  upheaval  of  Loeffgrund  amounted  to  2 
feet  11  inches  only.* 

Celsius  was  accused  of  impiety  by  the  divines  of  Stockholm  and  Upsal. 
The  Parliament,  indeed,  wished  to  cut  the  matter  short  by  a  vote ;  the  two 
orders  of  peasants  and  nobility  declared  themselves  incompetent  in  the 
*  Lyell ;  Robert  Chambers. 


532  ^^^  EARTH. 

matter,  while  the  representatives  of  the  clergy,  followed  timidly  by  the 
burgesses,  condemned  the  new  opinion  as  an  abominable  heresy.*  Never- 
theless, the  geologists  who,  since  the  last  century,  have  visited  the  coasts 
of  Sweden,  have  been  compelled  to  verify  and  complete  Celsius's  observa- 
tions. They  have,  however,  been  forced  to  reject  the  first  hypothesis  of 
the  gradual  subsidence  of  the  water,  and  to  recognize  as  a  fact  that  the 
movement,  attributed  in  error  to  the  liquid  mass  of  the  Baltic,  was  that  of 
the  continent  itself.  As,  indeed,  had  been  already  laid  down  by  Antonio 
Lazzaro  Moro,  an  Italian  savant^  it  was  the  earth,  and  not  the  sea,  which 
was  the  moving  and  shifting  element. f  In  fact,  if  the  sea-level  was  pro- 
gressively sinking,  as  was  once  supposed,  the  water,  the  surface  of  which, 
owing  to  gravity,  must  always  remain  horizontal,  would  retreat  equally 
all  round  the  Scandinavian  peninsula,  and  on  all  the  sea-shores.  But  this 
is  not  the  case.  At  the  northern  extremity  of  the  Gulf  of  Bothnia,  at  the 
mouth  of  the  Tornea,  the  continent  is  emerging  at  the  rate  of  5  feet  3 
inches  a  century,  but  by  the  side  of  the  Aland  Isles  it  only  rises  3^  feet  in 
the  same  time ;  south  of  this  archipelago  it  rises  still  more  slowly ;  and 
farther  down,  the  line  of  the  shore  does  not  alter  as  compared  with  the 
level  of  the  sea.  The  terminal  point  of  Scania  is  gradually  being  buried 
under  the  waters  of  the  Baltic,  as  is  proved  by  the  forests  which  have 
been  submerged.  Several  streets  of  the  towns  of  Trelleborg,  Ystad,  and 
Malmoe  have  already  disappeared;  the  latter  has  sunk  5  feet  2  inches 
since  the  observations  made  by  Linnaeus,  and  the  coast  has  lost,  on  the  av- 
erage, a  belt  32  yards  in  breadth. 

On  the  west  coasts  of  the  Scandinavian  peninsula  the  phenomena  prov- 
ing a  recent  upheaval  of  the  ground  are  just  as  numerous  as  on  the  eastern 
shores ;  but  the  rapidity  of  the  ascending  movement  has  not  yet  been 
measured,  although  it  is  certainly  less  considerable  than  in  Sweden.  The 
terminal  point  of  Jutland,  bounded  by  an  ideal  line  tending  obliquely  from 
Fredericia  toward  the  northwest,  rises,  according  to  Forchhammer,  1 1  •70 
inches  a  century.  At  Christiania  the  increase  is  perhaps  still  less,  for,  ac- 
cording to  Eugene  Kobert,  the  pavement  of  the  ancient  town  appears  to 
have  remained  stationary  for  three  hundred  years.  Lastly,  farther  to  the 
north,  the  present  position  of  several  edifices  situated  in  the  island  of 
Munkholm,  near  Trondhjem,  proves,  as  Keilhau  the  geologist  says,  that 
during  a  thousand  years  the  elevation  of  the  ground  has  been  less  than  20 
feet.  This  is  all  that  is  positively  known.  Nevertheless,  a  comparison 
of  the  various  lines  of  level,  and  an  examination  of  all  the  other  indications 
of  a  slow  upheaval,  seem  to  show  that,  in  spite  of  the  numerous  inequali- 
ties in  the  rate  of  progress  of  the  phenomenon,  that  portion  of  the  coast 
which  is  nearest  to  the  pole  is  rising  the  most  rapidly  out  of  the  water. 
Elevated  beaches,  which  can  be  traced  by  the  eye  like  the  steps  of  an 
amphitheatre,  are  ai'ranged  in  stages  at  various  heights  on  the  slopes  of 
the  mountains.     Heaps  of  modern  shells  are  found  at  heights  of  500  to 

*  Anton  von  Etzel,  Die  Ostsee. 

t  Von  HofF,  Veranderungen  der  Erdoherflache,  vol.  iii.,  p.  318,  319. 


UPHEAVAL  OF  SCANDINAVIA.  533 

050  feet  above  the  level  of  tlie  sea,  and  the  great  branches  of  pink  coral 
formed  by  the  Lophohelia  jyrolifera^  which  lives  in  the  sea  at  a  depth 
varying  from  1000  to  2000  feet,  are  now  raised  up  to  the  base  of  the  cliff.* 
The  pine  woods,  too,  which  clothe  the  summits,  are  continually  being  up- 
heaved toward  the  lower  snow-limit,  and  are  gradually  withering  away  in 
the  cooler  atmosphere ;  wide  belts  of  forest  are  composed  of  nothing  but 
dead  trees,  although  some  of  them  have  stood  for  centuries.f 

The  whole  body  of  facts  known  on  the  subject  of  the  movements  of  the 
ground  of  Scandinavia  will  therefore  warrant  savants  in  comparing  the 
whole  peninsula  to  a  solid  plane  turning  round  a  line  on  which  it  rests, 
und  raising  one  of  its  ends  so  as  to  lower  the  other  in  the  same  proportion. 
The  gulfs  of  Bothnia  and  Finland,  like  vessels  tilted  up  out  of  the  horizon- 
tal, slowly  pour  their  waters  into  the  southern  basin  of  the  Baltic.  Fresh 
islets  and  ranges  of  islets  appear  in  succession,  rocks  are  laid  dry,  and  if 
the  elevation  of  the  bed  of  the  sea  continues  to  take  place  with  tlfe  same 
regularity  as  during  the  historic  ages,  it  may  be  predicted  that  in  three  or 
four  thousand  years  the  archipelago  of  Qvarken,  between  Umea  and  Vasa, 
will  be  changed  into  an  isthmus,  and  the  Gulf  of  Tornea  will  be  converted 
into  a  lake  similar  to  that  of  Ladoga.  Later  still,  the  Aland  Islands  will 
become  connected  with  the  continent,  and  will  serve  as  a  bridge  between 
Stockholm  and  the  empire  of  Russia.  It  is,  besides,  very  probable,  if  not 
certain,  that  the  great  lakes  and  innumerable  sheets  of  water  which  fill  all 
the  granite  basins  of  Finland  have  taken  the  place  of  an  arm  of  the  sea 
which  once  united  the  Baltic  to  the  great  Polar  Ocean.  The  erratic  blocks 
of  granite  scattered  about  all  over  Russia  can  only  have  been  carried 
thither  by  trains  of  ice  which  have  made  their  ^ay  over  the  sea  from  the 
mountains  of  Sweden.  The  shells  belonging  to  polar  waters,  which  are 
foiu^  as  far  as  the  basin  of  the  Volga,  also  testify  in  favor  of  the  existence 
of  l^rmer  arm  of  the  sea.  The  name  of  Scandinavia  itself  signifies  "  Igle 
of  Scand,"  and  the  name  of  Bothnia  (Botten)  proves  that  these  coast  prov- 
inces were  formerly  a  marine  bed.|  Here  philology  steps  in  to  aid  geol- 
ogy and  tradition. 

This  is  not  all.  The  Baltic  Mediterranean  also  communicated  with  the 
North  Sea  by  a  wide  channel,  the  deepest  depressions  of  which  are  now 
occupied  by  the  lakes  Maler,  Hjelmar,  and  Wenern.  Considerable  heaps 
of  oyster-shells  are  found  in  several  places  on  the  heights  which  command 
these  great  lakes  of  Southern  Sweden.  On  the  rocks  now  laid  dry,  which 
surround  the  Gulf  of  Bothnia,  banks  of  these  molluscs  have  also  been  dis- 
covered exactly  similar  to  those  of  Norway  and  the  western  coasts  of  Den- 
mark. With  regard  to  the  celebrated  kjoekkenmceddings  of  the  Danish 
islands,  they  are  in  great  part  composed  of  oyster-shells,  which  the  inhab- 
itants, in  the  Age  of  Stone,  evidently  used  to  collect  in  the  bottoms  of  the 
neighboring  bays.     It  has  been  proved  by  the  investigations  of  M.  de  Baer 

*  Carl  Vogt,  Nordfahrt. 

t  Keilhau,  Bulletin  de  la  SorUti  Giologique  de  France,  First  Series,  toL  \\u 

X  Von  Maack ;  Eugene  Robert. 


534 


THE  EARTH. 


that  the  oyster  can  not  live  and  grow  in  water  holding  more  than  thirty- 
seven  parts  in  a  thousand  of  salt,  or  less  than  sixteen  or  seventeen  parts 


~T5f- 


Si^3    Linjfmdet  cites- eUif!L*9oooanf 


y'ToNV  '\ 


AM 


—  * 


Fig.  221.  Elevation  of  the  Bed  of  the  Gulf  of  Bothnia. 

in  a  thousand.     Now  the  Baltic  Sea,  into  which  its  numerous  tributaries 
bring  a  large  quantity  of  fresh  water,  does  not  contain,  on  the  average, 


ELEVA TION  OF  SCANLINA  VIA.  535 

more  than  five  parts  in  a  thousand  of  salt ;  and,  indeed,  in  some  of  the 
gulfs,  the  water,  now  devoid  of  all  its  former  inhabitants,  has  become  en- 
tirely fresh.  And  yet — the  heaps  of  oyster-shells  prove  it — the  Baltic  Sea 
and  the  inland  lakes  were  once  as  salt  as  the  North  Sea  is  at  the  present 
day.  Whence,  then,  could  this  saltness  proceed,  except  from  some  for- 
mer strait  which  occupied  the  depressions  in  which  the  Swedish  engineers 
have  dug  out  the  Trolhatta  Canal?  Besides,  when  the  sluices  were  being 
constructed,  there  were  found,  not  far  from  the  cataracts,  and  at  a  height 
of  40  feet  above  the  Cattegat,  various  marine'remains,  mingled  with  relics 
of  human  industry — boats,  anchors,  and  piles.  According  to  M.  de  Baer, 
it  is  not,  at  the  most,  more  than  five  thousand  years  before  our  century 
that  we  must  date  the  closing  up  of  the  straits  which  used  to  exist  between 
Southern  Sweden  and  the  great  mass  of  the  northern  plateaux. 

Since  Leopold  von  Buch  has  placed  beyond  all  doubt  the  important  fact 
of  the  gradual  upheaval  of  the  northern  portion  of  the  Scandinavian  pen- 
insula, several  geologists  have  ascertained  that  the  elevation  does  not  take 
place  in  a  mode  that  is  perfectly  uniform.  During  by-gone  centuries  the 
movement  has  sometimes  been  accelerated  and  sometimes  slackened,  as  is 
proved  by  the  inequality  of  the  elevated  sea-beaches  which  run  along  the 
sides  of  the.  mountains  on  the  coasts  of  Norway.  Some  of  these  steps  or 
shelves  that  the  waves  have  cai'ved  out  in  the  rook  are  wide  and  gently 
inclined ;  others  are  abrupt,  and  can  scarcely  be  distinguished  from  the 
slopes  above  them.  Lastly,  the  measurements  made  by  M.  Bravais  along 
the  lines  of  erosion  of  Altenfjord  have  proved  that  they  are  not  parallel, 
and  that  the  rocky  masses  situated  at  the  ends  of  the  gulfs  bave  been 
more  energetically  uphieaved  than  the  layers  lying  nearer  the  sea.  Thus 
the  upper  bank  of  Altenfjord  has  risen  at  the  eastern  end  to  a  height  of 


lituik  of  Altenfjord. 


219  feet  above  the  level  of  the  sea,  but  at  the  entry  of  the  bay  it  has  only 
risen  91  feet.  In  like  manner,  the  low6r  shelf,  throughout  the  whole  of  its 
immense  circuit  round  the  gulf,  presents  a  slight  inclination  toward  the 
sea,  being  no  less  than  88  feet  high  on  the  east,  and  only  45  feet  at  the 
outer  promontories.  Thus  the  action  of.nplieaval  is  evidently  stronger  in 
the  vicinity  of  the  mass  of  mountains  than  it  is  on  the  coast;  but  this  does 


536  ^^^  EARTH. 

not  afford  any  sufficient  reason  for  saying  that  at  a  certain  distance  to  the 
west,  under  the  bed  of  the  sea,  the  movement  of  the  ground  entirely  ceases.* 

M.  Carl  Vogt  has  propounded  an  ingenious  hypothesis  to  account  for 
this  inequality  of  elevation.  According  to  his  theory,  rocks  of  various  na- 
tures— schists,  sandstones,  or  limestone — which  compose  the  mountains  of 
the  Scandinavian  peninsula,  incessantly  swell  in  consequence  of  the  infil- 
tration of  snow-water,  and,  owing  to  fresh  crystallizati(Jns  taking  place  by 
means  of  moisture,  are  gradually  converted  into  masses  of  stratified  gran- 
ite. This  hypothesis,  which  "has  been  much  discussed  by  geologists,  would 
certainly  explain  the  raising  of  the  lines  of  erosion  of  the  Norwegian  coast 
near  the  groups  of  mountains,  but  it  would  fail  to  account  for  the  intervals 
of  comparative  repose,  and  especially  for  the  sinking  of  the  ground,  which 
many  geological  facts  prove  to  have  taken  place  during  the  glacial  period. 
It  is,  therefore,  necessary  to  admit  that  other  forces  have  been  in  action  iu 
the  solid  mass  of  Scandinavia. 

Added  to  this,  we  must  not  lose  sight  of  the  fact  that  the  upheaval  of 
this  peninsula  is  not  an  isolated  event,  and  that  the  other  countries  of  the 
north  of  Europe  and  Asia,  notwithstanding  the  diversity  of  their  rocks,  all 
appear  to  be  actuated  by  a  similar  movement  of  ascension.  The  islands 
of  Spitzbergen  exhibit  generally,  between  the  present  sea-shore  and  the 
mountains,  former  sea-beaches  which  are  gently  inclined,  and  half  a  mile  to 
two  miles  and  a  half  in  breadth,  on  which  are  found,  up  to  a  height  of  147 
feet,  heaps  of  bones  of  whales  and  shells  of  the  present  period.  These  re- 
mains, surrounding  all  the  snow-clad  slopes  of  Spitzbergen,  prove  that  this 
archipelago,  like  Scandinavia,  is  gradually  emerging  from  the  waves  of  the 
Polar  Ocean.f  The  northern  coasts  of  Russia  and  Siberia  are  likewise 
rising,  as  is  attested  by  popular  tradition  and  the  evidence  of  learned 
travelers.  MM.  De  Keyserling,  Murchison,  and  De  Verneuil  have  found,  at 
points  250  miles  to  the  south  of  the  White  Sea,  on  the  banks  of  the  Dwina 
and  the  Vaga,  beds  of  sand  and  mud  containing  several  kinds  of  shells  sim- 
ilar to  those  which  inhabit  the  neighboring  seas,  and  so  well  preserved 
that  they  have  not  lost  their  colors.  In  like  manner,  M.  De  Middendorf 
states  that  the  ground  of  the  Siberian  toundras  is  in  great  part  covered 
with  a  thin  coating  of  sand  and  fine  clay,  exactly  similar  to  that  which  is 
now  deposited  on  the  shores  of  the  Frozen  Ocean :  in  this  clay,  too,  which 
contains  in  such  large  quantities  the  buried  remains  of  mammoths,  there 
are  also  found  heaps  of  shells  perfectly  identical  with  those  of  the  adjacent 
ocean.  Far  inland,  besides,  trains  of  driftwood  are  seen,  the  trees  forming 
which  once  grew  in  the  forests  of  Southern  Siberia ;  these  trees,  having 
been  first  carried  into  the  sea  by  the  current  of  the  rivers,  have  been 
thrown  up  by  the  waves  on  the  former  coasts,  which  are  now  deserted  by 
the  sea.  It  is  this  half-rottA  wood  which  is  called  by  the  natives  "  Noah's 
wood,"  fancying  that  they  have  before  them  the  remains  of  the  ark  of  the 
deluge.  More  than  this,  there  are  also  direct  proofs  of  the  upheaval  of 
Siberia.     The  island  of  Diomida,  which  Chalaourof  noticed  in  1760  to  the 

*  Bravais,  Voyages  en  Scandinavie,  vol.  i. 

t  J>Ia\mgren, Mitt/ieilungen  von  Petennann,\o\.  ii,,  1863. 


GRADUAL  UrSISINO  OF  LAND.  537 

east  of  Cape  Sviatoj,was  found  to  be  joined  to  the  continent  at  the  date 
of  Wrangell's  voyage,  sixty  yeai"s  later.  It  is,  besides,  very  probable  that 
this  upheaval  of  the  ground  is  prolonged  to  the  east  over  a  great  portion 
of  the  circumpolar  land  of  North  America,  as  far  as  northern  Greenland,* 
for  numerous  indications  of  this  phenomenon  have  been  recognized  in  the 
Arctic  Isles  scattered  off  the  coasts  01  the  continent.  At  Port  Kennedy 
Mr.  Walker  found  shells  of  the  present  period  at  a  height  of  557  feet  above 
the  sea;  a  bone  of  a  whale  lay  at  a  height  of  164  feet.f 

The  cliflfs  of  Scotland  also  present  phenomena  similar  to  those  of  Scandi- 
navia. Parallel  water-marks  traced  out  by  the  waves  on  the  escarpments 
of  rocks,  and  collections  of  shells  peculiar  to  the  neighboring  seas,  attest 
the  gradual  elevation  of  this  portion  of  Great  Britain.  The  elevation,  too, 
must  have  been  of  a  much  more  regular  character  than  that  of  the  coasts 
of  Norway,  for,  according  to  Robert  Chambers,  not  the  slightest  variation 
of  level  is  noticed  on  the  ancient  terraces.  This  ascending  movement  is 
still  continuing ;  for  it  has  been  ascertained  that  the  marine  cliffs  which 
were  once  situated  above  the  estuaries  of  the  Forth,  the  Tay,  and  the 
Clyde  contain  not  only  organic  remains  of  recent  ages,  but  also  heaps  of 
pottery  of  Roman  origin.  The  former  Roman  port  of  Alaterva  (Cramond), 
the  quays  of  which  are  still  visible,  is  now  situated  at  some  distance  from 
the  sea,  and  the  ground  on  which  it  stands  has  risen  at  least  24^  feet.  In 
other  places  the  debris  scattered  on  the  bank  show  that  the  coast  has  risen 
about  26^  feet.J  Now,  by  a  remarkable  coincidence,  the  ancient  wall  of 
Antoninus,  which,  at  the  time  of  the  Romans,  served  as  a  barrier  against 
the  Picts,  comes  to  an  end  at  a  point  26  feet  above  the  level  of  high  tides. 
The  general  upheaval  of  the  region  may  therefore  be  estimated  at  0*195 
inch  a  year;  but  since  1810  the  movement  has  become  more  rapid,  as  is 
proved  by  the  tide-meters  at  the  port  of  Leith,  and  it  is,  at  present,  at  the 
rate  of  0'546  a  year.§  Farther  to  the  south,  on  the  sides  of  the  mountains 
of  Wales,  there  are  numerous  indications  of  the  presence  of  the  sea  during 
the  present  period.  Mr.  Darbishire  lately  discovered,  not  far  from  Snow- 
don,  at  a  height  of  1357  feet,  a  bed  of  drift  containing  fifty-four  species  of 
shells  of  similar  kinds  to  those  still  existing  in  the  northern  seas  of  Eu- 
rope ;  the  same  soil  was,  however,  found  at  a  point  650  feet  higher,  but  de- 
void of  shells. 

Thus,  from  Wales  to  Spitzbergen  and  the  eastern  coasts  of  Siberia,  the 
ground  has  continued  to  rise  slowly  during  a  portion  of  the  Glacial  period, 
and  also  during  the  present  epoch.  The  area  of  upheaval  includes  a  por- 
tion of  the  earth's  surface  which  is  not  less  than  160  degrees  of  longitude. 
In  the  face  of  these  facts,  are  we  to  consider  the  phenomena  of  uplieaval 
as  mere  local  accidents  produced  by  the  swelling  of  rocks  and  volcanic 
shocks,  or  must  we  look  upon  them  as  the  results  of  some  general  cause 
acting  in  various  ways  over  the  surface  of  the  whole  planet  ?  The  latter 
hypothesis  appears  to  us  to  be  the  more  probable. 

•  Vide  below,  p.  655.  t  Samuel  Haughton,  Natural  History  Review,  April,  1860. 

X  Arch.  Geikie,  JBt/in6tir^/i  New  Philosophical  Journal,  "Sew  Series,  xiv. 
S  Smith,  Geoloffica I  Mat/a :i lie,  September,  ISCC. 


53S  THE  EARTH. 


CHAPTER  LXXXI. 

UPHEAVAL   OF    THE   MEDITERRANEAN    REGIONS. — FORMER    LIBYAN    STRAIT. 
— COASTS    OF  TUNIS,  SARDINIA,  CORSICA,  ITALY,  AND  WESTERN  FRANCE. 

The  countries  of  the  South  of  Europe  certainly  possess  a  more  grace- 
fully-indented outline  than  any  other  regions  on  the  face  of  the  earth. 
The  peninsulas  which  they  throw  out  present  the  greatest  variety  of  con- 
tour and  aspect,  and  they  have  thus  become,  as  it  Avere,  imbued  with  vital- 
ity, owing  to  their  numerous  articulations,  similar  to  those  of  an  organized 
body.  Correspondent  with  this  multiplicity  of  external  shapes  are  the 
singular  irregularities  and  exceptional  contrasts  in  the  movements  of  the 
ground.  A  certain  complication  is  here  and  there  manifested  between  the 
upheaved  regions  and  those  which  are  subsiding.  Nevertheless,  a  suffi- 
cient number  of  observations  have  been  collected  to  warrant  us  in  admit- 
ting, in  a  general  way,  the  qlevation  of  most  of  the  countries  which  sur- 
round the  basin  of  the  Mediterranean.  These  regions,  which  in  several 
places  have  been  caused  to  oscillate  by  volcanic  forces,  constitute  a  con- 
siderable area  of  upheaval,  extending  from  the  deserts  of  the  Sahara  to 
Central  France,  and  from  the  coasts  of  Spain  to  the  steppes  of  Tartary. 
The  mountainous  peninsula  of  Scandinavia  is  situated  in  the  middle  of  the 
upheaved  regions  of  Northern  Europe,  and,  by  a  kind  of  polarity,  the  long 
depression  of  the  Mediterranean  occupies  the  centre  of  the  vast  areas  in 
the  South  of  Europe  and  Northern  Africa,  which  are  gradually  rising. 

This  immense  space  was  once  bounded,  toward  the  tropical  zone,  by  an- 
other sea,  or  at  least  by  a  strait  several  hundreds  of  miles  in  width,  which 
commenced  at  the  Gulf  of  Syrtes,  and,  filling  up  the  depressions  of  the 
Berber  Sahara,  joined  the  Atlantic  in  front  of  the  archipelago  of  the  Ca- 
naries. In  1863  MM.  Escher  von  der  Linth  and  Desor  ascertained,  accord- 
ing to  M.  Charles  Laurent,  that  the  sands  of  these  regions  are  entirely 
identical  with  those  of  the  nearest  Mediterranean  shores,  and  contain  the 
same  species  of  shells.  One  of  these  witnesses  of  the  past,  the  common 
cockle  {Cardium  edule),  is  found  not  only  on  the  surface  of  the  ground, 
but  also  at  some  depth,  and  likewise  up  to  a  height  of  900  feet  upon  the 
sides  of  the  hills.  The  Algerian  Sahara  has,  therefore,  risen  to  this  extent 
during  a  recent  geological  period.  Various  depressions,  the  surface  of 
which  is  lower  than  the  level  of  the  Mediterranean,  have  been  gradually 
separated  from  the  sea,  and,  in  the  present  day,  they  exhibit  nothing  but 
marshy  pools  or  interminable  plains.  At  a  recent,  and  perhaps  historical 
epoch,  Lake  Tritonis  of  the  ancients,  now  the  Sebkha  Faraoun,  into  which 
flowed  the  Igharghar,  has  ceased  to  be  a  prolongation  of  the  Gulf  of 
Gabes,  and  has  become  a  mere  marsh.     It  was  the  last  remnant  of  the 


VPHEAVAL  OF  THE  MEDITERRANEAN  BEG  IONS.  53Q 

arm  of  the  sea  which  separated  the  mountainous  regions  of  Atlas  from  the 
African  continent,  both  so  distinct  in  their  general  character,  as  well  as  in 
their  fauna  and  flora.  To  the  existence  of  this  African  Mediterranean, 
which  is  now  replaced  by  white  sands,  beds  of  salt,  and  rocks  devoid  of 
verdure,  MM.  Escher  von  der  Linth  and  Lyell  in  great  part  attribute  the 
enormous  extent  of  the  former  glaciers  of  Europe.  It  is,  in  fact,  very  nat- 
ural to  think  that,  before  the  drying  up  of  this  inland  sea,  the  masses  of 
air  blown  to  the  north  would  become  saturated  with  moisture  while  pass- 
ing over  the  water,  and,  rising  gradually  to  the  higher  regions,  would  con- 
stantly convey  fresh  layers  of  snow  to  the  summits  of  the  Alps,  instead  of 
melting  the  snow,  as  the  foh7i  now  does,  heated  as  it  is  by  the  reflection 
from  the  burning  sand  of  Africa.*  It  ;s,  however,  possible  that  the  Swiss 
mountains  have  decreased  in  height  since  the  Glacial  period.  The  same 
slow  oscillation  of  the  ground  which  emptied  the  Libyan  Mediterranean 
has,  perhaps,  by  its  reaction,  lowered  the  foundations  of  the  Alps,  and 
brought  them  nearer  to  the  level  of  the  sea.f 

On  the  coasts  of  the  Mediterranean,  the  indications  which  would  lead  us 
to  infer  the  fact  of  some  upheaval  of  the  ground  are  plentiful  enough. 
Thus  the  shores  of  Tunisia  are  constantly  encroaching  on  the  sea.  The 
ancient  ports  of  Carthage,  Utica,  Mahedia,  Porto  Farina,  Bizerta,  and  oth- 
ers, are  now  filled  up.|  The  bays  are  done  away  with,  the  points  advance 
farther  and  farther  into  the  sea ;  and  these  phenomena  take  place  with  a 
rapidity  sufiicient  to  show  that  we  are  witnessing  the.efl'ect  of  a  vertical 
impulse  similar  to  that  which  once  upheaved  the  beds  of  the  Saharan  seas. 
In  like  manner,  Sicily  appears  to  be  constantly  elevated  by  the  forces  in 
action  under  the  beds  of  its  surface.  On  the  heights  which  command  Pa- 
lermo, caves  have  been  observed  at  an  elevation  of  180  feet,  which  have 
been  hollowed  out  by  the  sea  during  a  period  characterized  by  existing 
species  of  Bhell-fish.§  On  the  eastern  coast  of  the  island,  Gemellaro  has 
recorded  a  recent  upheaval  of  more  than  42  feet.  In  Sardinia,  not  far 
from  Cagliari,  M.  De  la  Marmora  points  out,  as  existing  at  heights  of  242 
and  231  feet,  deposits  which  contain  remnants  of  pottery  mixed  with  mod- 
ern shells,  which  deposits,  in  his  idea,  were  on  a  level  with  the  sea  at  a 
date  when  the  island  was  inhabited  by  man.  Certainly  M.  Emilien  Dumas, 
an  excellent  observer,  considers  that  these  remnants  of  pottery  and  heaps 
of  shells  are  nothing  but  the  remnants  of  the  cooking  of  food,  similar  to 
the  kjoekkenmoeddings  of  Denmark.  If  this  be  the  case,  there  would  be 
nothing  to  prove  that  Sardinia  was  upheaved  at  any  recent  epoch.  But 
are  the  enoraious  banks  of  oyster-shells  which  cover  the  ground  at  the 
Lake  of  Diana,  6  feet  above  the  level  of  the  sea,  and  are  continued  far  un- 
der the  water,  to  be  considered  as  nothing  but  the  debris  of  Roman  ban- 
quets ?  Such  an  idea  does  not,  at  least,  appear  at  all  probable  to  M.  Au- 
capitaine  and  a  number  of  other  observers. 

*  Vide  the  chapter  on  "Winds." 

t  Lvell,  Inaugural  Address  to  the  British  Assot:iation  at  Bath,  ISCA. 

X  Guerin,  Voyat/e  Archiolof/ique  a  la  R^gencc  de  Tunis.  §  Lyell,  ^lii/j'«7t«Vy  of  Man. 


54(3  ^^^  EARTH. 

The  facts  of  upheaval  brought  forwai-d  by  geologists  as  regards  the 
other  regions  of  the  coast  of  the  Mediterranean  are  not  as  yet  sufficiently 
verified,  and  it  can  not  be  positively  asserted  that  these  shores  have  risen 
above  the  sea  during  the  present  period.  Nevertheless,  the  body  of  evi- 
dence is  of  considerable  importance,  and  merits  serious  consideration. 
Thus,  round  the  former  island  of  Circe,  now  become  a  promontory  of  Tus- 
cany, the  rocks,  which  have  much  the  appearance  of  a  former  sea-beach, 
are  pierced  by  pholades.^  With  regard  to  the  discovery  of  banks  of  mod- 
ern shells  made  by  Risso  near  Villefranche,  at  the  extremity  of  the  Cape 
of  Saint  Hospice,  M.  Emilien  Dumas  disputes  its  scientific  value.  Never- 
theless, it  is  plain  that  this  coast,  and  the  whole  of  the  adjacent  shore  as 
far  as  Spezzia,  were  covered  by  sea-water  at  a  recent  geological  epoch. 
All  that  is  necessary  to  prove  this  is  to  examine  the  caves  of  Menton,  of 
Ventimiglia,  and  of  the  Cape  of  Noli,  which  were  hollowed  out  by  the 
waves  at  some  former  date,  and  open  like  rows  of  arched  doors  and  win- 
dows along  the  fa9ade  of  some  palace. 

The  southern  coasts  of  France  do  not  afford  any  direct  evidence  of  an 
upheaval  of  the  soil ;  but  various  indications  possess  a  value  which  can 
not  be  disputed.  Astruc,  of  Languedoc,  brings  forward  a  great  number 
of  facts,  which  prove  that,  at  the  time  of  the  Romans  and  in  the  Middle 
Ages,  the  marshes  extended  much  farther  inland.  The  ancient  Roman 
road  from  Beaucaire  to  Beziers  describes  a  wide  curve  toward  the  north, 
doubtless  to  avoid  the  plains  on  the  shore,  which  were  then  entirely  under 
water.  Ancient  cities  with  Gallic  names — as  Ugemum  (Beaucaire)  and 
Nemausus  (Nismes) — are  found  along  the  ancient  road,  while  all  the  places 
situated  to  the  south  bear  Latin  or  Roman  names — as  Aigues  Mortes,Fran- 
quevaux,Vauvert,  and  Frontignan  {Frons  stagni) — and  appear,  therefore, 
to  be  of  more  modern  origin.  It  is,  besides,  proved  by  various  documents 
that  ancient  ports  have  filled  up,  and  have  been  converted  into  terra  Jirma. 
Astruc  also  points  out  the  remarkable  fact  that  the  Romans,  who  highly 
appreciated  thermal  springs,  were  not  aware  of  the  abundant  wells  of 
Balaruc,  although  the  eddies  of  steam  could  not  have  failed  to  point  them 
out  if  they  had  not  been  covered  at  that  time  by  the  waters  of  the  Lake 
Thau.  This  is  an  important  argument  in  favor  of  the  hypothesis  of  a 
gradual  elevation  of  this  part  of  France. 

Beyond  the  Mediterranean  basin  this  movement  of  general  upheaval 
appears  to  continue  toward  the  north  and  west.  Thus,  at  Seixal,  opposite 
Lisbon,  they  have  been  compelled  to  cease  building  ships  of  the  line  on 
account  of  the  increasing  diminution  of  the  water,  which  is  attributed  both 
to  the  deposits  of  mud  and  also  to  the  upheaval  of  the  rocks.  On  the  At- 
lantic coasts  of  France  a  great  number  of  phenomena  of  a  similar  nature 
have  also  been  adduced.  To  many  geologists,  especially  to  M.  Bravais,  it 
seems  probable  that  the  whole  of  France,  agitated  by  a  slight  and  almost 
imperceptible  tremor,  is  being  slowly  upheaved  on  the  southern  side,  and 
turns  on  a  base-line  passing  through  the  peninsula  of  Brittany.  At  all 
*  Romanelli,  Breislnk,  quoted  by  Bottger,  Mittelmeer, 


VTHEAVAL  OF  THE  COASTS  OF  EUROPE,  54;^ 

events,  the  coasts  of  Poitou,  Aunis,  and  Saintonge  appear  to  have  risen 
since  the  commencement  of  the  historical  epoch.  Guerande,  Croisic, 
Bourgneuf,  and  Sables  d'Olonne  show  upon  their  shores  unquestionable 
traces  of  recent  elevation.  The  former  Gulf  of  Poitou,  the  entrance  of 
which,  two  thousand  years  ago,  was  not  less  than  18  to  25  miles  in  width, 
which,  too,  penetrated  inland  as  far  as  Niort,  has  constantly  contracted  its 
dimensions  since  the  above-named  date,  and  is  now  nothing  more  than  a 
small  bay,  known  under  the  name  of  the  Creek  of  Aiguillon.*  The  con- 
stant deposit  of  marine  alluvium  would  scarcely  be  a  sufficient  cause  for 
this  i-apid  increase  of  the  land ;  it  is  therefore  probable  that  at  this  spot 
the  upper  layers  of  the  ground  are  regularly  in  a  course  of  upheaval 
Farther  to  the  south.  La  Rochelle,  which  owes  its  name  to-  the  position 
which  it  once  occupied  on  a  rock  almost  isolated  in  the  midst  of  the  water, 
now  only  communicates  with  the  sea  by  a  narrow  channel,  often  choked 
up  with  mud.  Brouage,  another  fort  which,  in  the  Middle  Ages,  was  a 
town  of  important  trade,  is  now  nothing  more  than  a  ruin,  some  distance 
from  the  sea.  ^The  district  of  Marennes,  to  which  the  name  of  "  Colloque 
des  lies"  was  once  given,  is  now  entirely  connected  with  the  main  land, 
and  the  arms  of  the  sea  which  cross  it  have  been  converted  into  draining- 
channels,  salt  marshes,  and  oyster-beds.  In  like  manner,  the  peninsula  of 
Arvert,  situated  between  the  mouth  of  the  Seudre  and  that  of  the  Gironde, 
ceased  to  be  an  archipelago  during  the  course  of  the  Middle  Ages.  At 
Rochefort  it  has,  indeed,  been  calculated  approximately  how  much  the 
ground  has  risen,  the  slips  for  ship-building,  dug  out  in  the  time  of  Louis 
XIV.,  having  been  gradually  elevated  more  than  a  yard.f  "  The  bank  is 
pushing  up,"  say  the  inhabitants  of  the  coast,  who  have  long  since  ob- 
served the  gradual  upheaval  of  the  ground. 

*  De  Quatrefages,  Les  Cotes  de  la  Saintonge. 

t  Babinet,  Revue  des  Deux-Mondes,  September  1 5, 1 855.  ■ 


r542  ^^^  EARTH. 


CHAPTER  LXXXn. 

COASTS   OP  ASIA  MINOR. — ANCIENT    OCBAN   OF   HYECANIA. — COASTS    OP 
PALESTINE    AND   EGYPT. — THE   ADRIATIC   GULP. 

Phenomena  of  upheaval  are  also  very  common  in  the  islands  and  round 
tlie  edge  of  the  eastern  basin  of  the  Mediterranean.  Like  Sicily  and  sev- 
eral parts  of  the  coasts  of  Italy  and  Greece,  a  considerable  number  of  isl- 
ands— as  Malta,  Rhodes,  and  Cyprus—  are  surrounded  with  circular  ter- 
races more  or  less  elevated  above  the  level  of  the  sea,  and  composed  of 
calcareous  or  sandy  rocks  of  recent  formation.*  The  northern  portion  of 
the  island  of  Crete  has  risen  more  than  60  feet  during  the  present  geolog- 
ical period.f  A  study  of  the  shores  of  Asia  Minor  proves  that  there  also 
the  ground  has  continued,  since  man  inhabited  that  region-,  to  rise  with  a 
rather  rapid  movement.  During  historic  times  this  part  of  the  continent 
has  gained  a  considerable  belt  of  land  at  the  expense  of  the  -(Egean  Sea. 
It  is  not  the  alluvium  of  the  rivers,  or  the  matter  washed  up  by  the  sea, 
which  has  caused  this  increase  of  the  land,  for  the  Anatolian  rivers  are 
very  inconsiderable,  and  the  water  which  bathes  the  coast  can  not,  on  ac- 
count of ^ts  great  depth,  throw  up  much  sand.  It  must,  therefore,  be  in 
consequence  of  a  slow  upheaval  of  the  earth's  crust  that  the  ruins  of  Troy, 
Smyrna,  Ephesus,  and  Miletus  have  gradually  become  more  distant  from 
the  coast,  and  appear  to  be  receding  still  farther  inland.  From  the  same 
cause  so  many  islands  in  the  -^gean  Sea  which  were  once  separate  are 
now  united,  or  are  connected  with  the  main  land,  and  form  headlands  or 
Ijills  surrounded  by  low-lying  plains.  The  testimony  of  ancient  authors  is 
imanimous  as  to  these  encroachments  of  the  shores.  Thus  it  is  said  that 
the  two  halves  of  Lesbos,  Issa,  and  Antissa  have  become  united,  that  the 
bays  have  been  converted  into  inland  lagoons,  and  that  various  islands 
have  joined  on  to  the  main  land  at  Mindus,  Miletus,  the  Parthenion  Cape, 
at  Ephesus,  also  at  points  near  Halicamassus  and  Magnesia.  At  the  time 
of  Herodotus,  the  mountain  of  Lade,  not  far  from  which  the  Ionian  galleys 
fought  a  battle  with  the  Persian  fleet,  was  an  island ;  at  the  present  day 
it  forms  part  of  the  main  land,  and  stands  in  the  midst  of  the  plain  of  the 
Meander.  Since  the  date  of  Strabo  and  Pliny,  several  other  islands  have 
similarly  become  headlands.  The  former  Latmican  Gulf  is  converted  into 
a  lake,  known  under  the  name  of  Akiz.  The  encroachments  oi terra  firma 
on  this  gulf  have  added  to  the  eastern  coast  of  Asia  Minor  about  67  square 
miles  in  less  than  two  thousand  years.  This  retirement  of  the  sea  took 
place  likewise  in  preceding  ages,  for  the  town  of  Priene  (Samsoun),  which 
at  the  time  of  Strabo  was  4|-  miles  from  the  shore,  had  been  built  at  a  pre- 
vious date  on  the  sea-coast.     In  like  manner,  the  village  of  Ayasoulouk, 

*  Albert  Gaudry,  Revue  des  Deux-Mondes,  November  1, 1861 ;  Newbold. 
t  Raiilin  ;  Leycester  and  Spratt.      Vide  p.  545. 


ELEVATION  OF  ASIA  MINOR.  543 

where  the  ruins  of  the  ancient  city  of  Ephesus  may  still  be  seen,  is-at  the 
present  time  two  leagues  from  the  coast,  and  the  former  estuary  which 
was  commanded  by  the  town  is  now  converted  into  a  marshy  plain. 
Would  the  little  river  Meander,  the  total  length  of  which  is  not  more  than 
341  miles,  have  been  able,  by  nothing  but  its  alluvial  deposits,  to  fill  up 
lakes  and  estuaries  of  so  large  an  area,  and  to  modify  so  considerably  the 
outline  of  the  shore  ?  It  is  therefore  important  that  the  discharge  of  this 
river  and  its  annual  deposit  of  alluvium  should  be  exactly  measured,  in 
order  that  we  may  arrive  certainly  at  the  real  cause  of  these  encroach- 
ments on  the  part  of  the  Anatolian  coast,  where,  according  to  the  ancient 
saying  of  Pausanias, "  all  is  unstable  and  changing."  According  to  M.  De 
Tchihatcheff,  this  portion  of  the  coast  of  Asia  Minor  has  gained,  since  his- 
toric times  began,  an  extent  of  about  185  square  miles,  equal  to  the  area 
of  the  Isle  of  Wight.* 

Similar  phenomena  are,  however,  likewise  taking  place  on  the  southern 
coast  of  Asia  Minor.  Near  Adalia,  the  Lake  of  Capria,  which  was  very 
extensive  at  the  time  of  Strabo,  first  ceased  to  communicate  with  the  sea, 
and  then  gradually  emptied,  being  now  nothing  but  a  marshy  hollow : 
the  surface  of  the  peninsula  has  thus  been  increased  by  an  area  of  154 
square  miles.  On  the  north  of  Asia  Minor  a  great  number  of  signs  prove 
that  there  also  the  water  has  retreated  before  the  shores  and  rocks  of  the 
continent.  During  the  present  geological  period  the  area  of  the  Euxine 
has  been  diminished,  and,  according  to  the  traditions  of  the  Crimean  Tar- 
tars, it  is  still  diminishing.  Banks  of  modern  shells  have  been  left  by  the 
sea  at  considerable  heights  on  the  hills  of  Thrace  and  Anatolia  ;f  round 
the  Crimea,  salt  lakes,  stagnant  marshes,  now  exist  far  inland  in  the  place 
of  former  gulfs.  Certainly  enough  the  Black  Sea,  before  the  opening  of 
the  Bosphorus,  received  from  its  tributary  rivers  more  water  than  the  sun 
and  wind  could  evaporate,  and  must  necessarily  have  much  exceeded  the 
level  to  which  it  now  reaches.  But  if  the  earth  itself  had  remained  sta- 
tionary, and  had  not  slowly  risen,  the  sea-water  would  not  have  left  the 
marks  of  its  presence  at  any  point  higher  than  the  former  Strait  of  Isnik, 
the  site  of  which  is  now  dotted  over  with  lakes  which  once  formed  a  part 
of  the  sea.  It  is,  perhaps,  in  consequence  of  the  upheaval  of  the  ground 
that  this  strait  was  closed,  and  the  water  of  the  Black  Sea,  gradually 
accumulating  in  its  basin,  was  compelled  to  open  by  force  a  new  outlet 
through  the  volcanic  fissures  which  have  now  become  the  Bosphorus. 

A  geological  examination  of  Southern  Russia  and  the  plains  of  Tartary 
will  preclude  us  from  entertaining  any  doubt  as  to  the  fact  that  the  Cas- 
pian Sea,  the  Sea  of  Aral,  and  all  those  innumerable  sheets  of  water  which 
are  scattered  over  the  steppes,  were  separated  from  the  Euxine  and  the 
Gulf  of  Obi  by  a  gradual  upheaval  of  the  continent.  The  plains  are  still 
covered  with  salt  and  marine  remains.  The  inland  seas  and  the  scattered 
lakes  are  still  inhabited  by  seals,  and  their  fauna  altogether  presents  an  es- 
sentially oceanic  character.     Herodotus,  Strabo,  Ptolemaeus,  and  all  the 

*  Asie  Mineure.     Von  Hoff,  Ver&nderungen  der  Erdoberfldche. 
t  De  Tchihatcheff,  Le  Boaphore  et  Constantinople. 


544  THE  EAETH. 

authors  of  antiquity  attribute  to  the  ancient  Hyrcanian  Ocean  an  extent 
far  larger  than  that  of  the  Caspian  of  our  day ;  most  of  them,  indeed,  con- 
sidered this  inland  sea  as  a  prolongation  of  the  Frozen  Ocean.  This  lat- 
ter opinion,  no  doubt  erroneous  as  regards  a  date  two  thousand  years  ago, 
would  certainly  have  been  true  of  some  anterior  epoch.  After  Humboldt's 
profound  investigations  on  Central  Asia,  we  shall  not,  at  the  present  day, 
show  too  great  temerity  in  assuming  that,  during  some  portion  of  the 
present  period,  a  vast  strait,  like  that  which  once  ran  along  the  southern 
base  of  the  Atlas,  extended  from  the  Black  Sea  to  the  Gulf  of  Obi  and  the 
Frozen  Ocean.*  The  vast  depression  of  the  Caspian  plains  which  is  below 
the  level  of  the  sea,  and,  according  to  Halley,  was  produced  by  the  shock 
of  some  wandering  comet,  is,  on  the  contrary,  really  owing  to  a  slow  ele- 
vation of  the  ground. 

The  observations  of  level  made  on  the  coasts  of  the  Mediterranean  have 
enabled  us  to  ascertain  not  only  that  the  lai'ger  portion  of  this  inland  ba- 
sin of  the  ancient  world,  and  many  of  the  regions  bordering  on  it,  have 
gradually  risen,  but  that  they  have,  in  addition,  pointed  out  the  limits  of 
the  area  of  upheaval.  They  may  be  distinguished  with  some  degree  of 
precision  on  the  coast  of  Syria  and  Palestine ;  it  may  be  noticed  that  in 
this  region  the  surface  of  the  ground  is  corrugated  like  that  of  water,  and 
forms  a  series  of  waves  and  depressions  fluctuating  in  contrary  directions. 
The  shores  of  the  Gulf  of  Iskanderoun  are  regularly  gaining  in  width  by 
means  of  the  elevation  of  the  ground  as  well  as  of  the  matter  thrown  up 
by  the  sea ;  but  at  Beyrout  a  tower  is  shown  which  is  sinking  farther  and 
farther  into  the  water.  More  to  the  south,  the  former  Isle  of  Tyre  is  now 
connected  with  the  continent,  and  several  parts  of  the  peninsula  bear 
traces  of  the  sojourn  of  the  sea  during  some  recent  epoch.  Lastly,  Kaisa- 
rieh  and  some  other  towns  in  Palestine  are  included  in  an  area  of  subsi- 
dence, as  is  proved  by  the  remains  of  fortifications  which  are  now  visible 
below  the  level  of  the  Mediterranean. 

On  the  east,  all  the  Egyptian  coasts  were  still  rising  at  a  comparatively 
very  recent  epoch,  for  the  Bitter  Lakes  and  the  banks  of  the  Nile  exhibit 
former  sea-beaches  on  which  modern  shells  are  found.  But  at  the  present 
day  the  ground  is  sinking  continuously  and  imperceptibly.  Ruined  towns 
are  situated  in  the  midst  of  the  marshy  plain  of  Lake  Menzaleh,  which  is 
covered  by  the  sea  during  the  greater  part  of  the  year.  Farther  on,  a  for- 
mer branch  of  the  Nile,  with  the  banks  which  bordered  it,  is  entirely  hid- 
den by  the  waters  of  the  Mediterranean.  The  same  phenomenon  occurs 
on  the  other  side  of  the  Delta.  In  1784  the  sea  made  an  irruption  into  the 
interior  of  the  land,  and  formed  the  Lake  of  Aboukir  in  the  midst  of  a 
plain  on  which  important  towns  once  stood.  In  like  manner  it  may  be  in- 
ferred, from  the  ancient  descriptions  of  Alexandria  and  its  environs,  that  a 
considerable  subsidence  of  the  ground  must  have  taken  place  there  during 

*  In  Captain  Maury's  magnificent  studies,  in  which,  however,  imagination  sometimes  has 
as  large  a  share  as  science,  he  endeavors  to  prove,  by  very  ingenious  arguments,  that  the  up- 
heaval of  the  Andes,  by  modifying  the  system  of  winds  and  rain  over  the  whole  earth,  was  the 
cause  of  the  gradual  drj-ing  up  of  the  plains  of  the  Caspian  and  Aral. 


COASTS  OP  EQ  TFT.— THE  ADRIATIC.  545 

the  centuries  of  our  era.  Artificial  caves  and  catacombs,  dug  out  in  the 
days  of  the  Ptolemies,  and- incorrectly  known  as  "Cleopatra's  Baths,"  are 
now  invaded  by  the  waves.*  On  the  shores  of  the  Red  Sea,  not  far  from 
Suez,  some  sepulchral  caves  hollowed  out  in  the  calcareous  rock  have  like- 
wise been  inundated,  owing  to  the  subsidence  of  the  ground.  Perhaps 
this  movement  in  the  ground  of  Egypt  is  common  to  all  that  portion  of 
the  Mediterranean  which  may  be  called  the  Egyptian  Sea ;  for  in  the  isl- 
and of  Crete  the  western  point  has  constantly  risen  during  the  modem 
epoch,  but  the  side  nearest  to  Egypt  is  gradually  sinking  under  the  w'ater. 
As  Strabo  himself  expressly  said.  Nature  is  seeking  to  destroy  the  Isthmus 
of  Suez,  which  she  once  formed  between  the  two  continents.  Man,  in  his 
operations  of  cutting  through  it,  is  only  anticipating  the  geological  labor 
of  centuries  to  come. 

Along  the  shores  of  the  Adriatic  Sea,  to  the  north  of  Zara  andPesaro, 
geographers  have  noted  other  phenomena  of  depression  which  mark  the 
northern  limit  of  the  great  Mediterranean  area  of  upheaval  In  the  mid- 
dle of  the  sixteenth  century  Angiolo  Eremitano  propounded  the  opinion 
that  the  isles  of  Venice  were  sinking  at  the  rate  of  about  a  foot  a  century, 
and  this  hypothesis,  which  was  based  upon  a  comparison  of  the  buildings 
and  the  pavement  of  the  streets  with  the  water,  has  since  been  fully  con- 
firmed. In  the  Isle  of  St.  George,  Roman  constructions  are  now  found  be- 
low tlie  level  of  the  lagoons  ;  in  other  places  paved  roads  are  covered  by 
the  water,  and  churches  and  bridges  have  sunk  in  comparison  with  the 
surface  of  the  sea.  In  1731  Eustache  Manfredi  noted  the  same  subsHfence 
of  the  soil  under  the  edifices  of  Ravenna,  but  he,  in  error,  attributed  it  to 
the  gradual  elevation  of  the  level  of  the  Adriatic.  In  addition,  an  entire 
town — Conca — once  situated  not  far  from  the  Cattolica,  at  the  mouth  of 
the  Crustummio,  has  been  entirely  submerged  for  some  centuries,  and, 
when  the  sea  is  calm,  the  remains  of  two  of  its  towers  may  still  be  seen 
under  the  waves.  M.  Giacinto  Collegno  thinks  that  all  these  alterations 
of  level  are  produced  by  the  deposit  of  the  alluvium  brought  down  by  the 
Po  and  the  other  rivers  descending  from  the  Apennines  and  the  Alps. 
This  is  a  cause  which  must  certainly  contribute  in  no  small  extent  to  the 
general  depression  of  the  Venetian  coasts  of  the  Adriatic  Sea,  but  proba- 
bly it  is  not  the  only  cause,  for  the  opposite  coasts  of  Dalmatia  and  Istria 
are  also  sinking,  in  spite  of  the  compact  nature  of  their  rocks.  At  Trieste, 
at  Zara,  and  in  the  Isle  of  Poragnitza,  various  works  of  man — such  as  pave- 
ments, mosaics,  and  sepulchres — may  be  seen  below  the  level  of  the  sea,f 
Moreover,  as  Lyell  remarks,  the  artesian  borings  which  have  been  made 
in  the  delta  of  the  Po  to  a  great  depth  below  the  sea  have  brought  up 
nothing  but  river  alluvium,  which  unquestionably  establishes  the  fact  of  a 
gradual  depression  of  the  ground.  The  earth  which  is  penetrated  by  the 
boring-rod  at  the  bottom  of  the  artesian  wells  was  once  situate  above  the 
level  of  the  sea. 

*  JjjfiW,  Antiquity  of  Man ;  Pococke;  Wilkinson;  Rchleiden. 
t  Donati,//«s^oire  Naturelle  de  la  Mer  Adriatique ;  Schleiden,  LtiPlante, 

M  M 


546 


THE  EARTH. 


CHAPTER  LXXXm. 

SUBSIDENCE    OP    THE    SHORE    OF    THE    CHANNEL    OF    HOLLAND,    OF 
SCHLESWIG,  OP  PRUSSIA. 

Whether  it  be  that  the  whole  of  Central  Europe  participates  in  the 
movement  of  depression  to  which  the  shores  of  the  Adriatic  are  subject, 
or  whether  the  latter  be  merely  a  local  phenomenon,  it  is  nevertheless  the 
case  that  the  southern  coasts  of  the  Channel  and  North  Sea  are  also  sink- 
ing, although  very  slowly.  On  the  coast  of  Bi'ittany  and  Normandy,  nu- 
merous forests  which  have  been  submerged,  and  buildings  surrounded  by 
the  sea-water,  prove  that  the  ground  has  sunk  during  the  present  period. 
In  709,  the  monastery  of  Mount  St.  Michael  was  built  in  the  midst  of  a 
forest  ten  leagues  (?)  from  the  sea ;  it  now  stands,  like  an  island,  in  the 
midst  of  sand-banks.  The  inroads  of  the  sea  are  still  continuing,  especially 
in  the  Bay  of  La  Hougue  and  in  the  harbor  of  Carteret.*  It  appears,  how- 
ever, that  various  undulations,  like  those  on  the  coast  of  Syria,  also  exist 
on  these  coasts,  for  in  several  places  banks  of  sand  and  modern  shells  have 
been  discovered  at  heights  from  40  to  50  feet  above  the  level  of  the  sea. 
At  some  remote  epoch,  but  nevertheless  contemporary  with  man,  the  val- 
ley 9(  the  Somme  was  also  upheaved,  but  for  thousands  of  years  it  has 
been  slowly  subsiding,  as  submarine  foi*ests  are  found  along  the  coast, 
and  the  peat-bogs  of  Abbeville,  the  bottom  of  which  is  situated  below  the 
Bay  of  Somme,  afford  no  other  debris  but  the  remains  of  animals  and  veg- 
etables which  lived  on  the  earth  or  in  fresh  water.  When  these  peat- 
mosses began  to  grow,  the  ground  of  the  valley  must  have  been  higher 
than  the  surface  of  the  neighboring  seas.f 

In  Flanders  and  Holland  the  phenomena  of  subsidence  have  been,  if  not 
more  considerable,  at  least  more  important  in  their  results,  on  account  of 
the  very  low  level  of  these  countries  in  comparison  with  the  sea.  A  mere 
enumeration  of  the  successive  catastrophes  brought  about  by  this  gradual 
depression  constitutes  a  terrible  history.  The  plains  of  Dordrecht  have  be- 
come a  forest  of  reeds  (Biesbosch).  The  Zuyder  Zee  itself — once  a  marsh, 
next  a  lake,  and  then  an  arm  of  the  sea— ris  still  continuing  to  sink:  at  the 
present  time  there  is,  it  is  said,  sufficient  depth  for  ships  of  heavier  burden 
than  those  which  used  to  navigate  it  in  former  centuries.  Like  a  raft 
gradually  sinking  under  the  waves,  Holland  would  be  slowly  swallowed 
up  in  the  abyss  if  it  were  not  that  the  inhabitants,  accepting  the  contest 
with  the  elements,  have  walled  in  their  country  by  means  of  dikes,  and 
laid  it  dry  by  immense  operations  of  drainage,  which  will  never  cease  to 
be  a  subject  of  astonishment.    Several  savants^  at  the  head  of  whom  stands 

*  Bonissent,  Congres  Scientijique  de  Cherbourg,  1860. 
t  Lyell,  A  ntiquity  of  Man. 


SUBSIDENCE  OF  HOLLAND.  547 


Fig.  223.  Biesbosch. 

the  eminent  geologist  M.  Staring,  are  of  the  opinion  that  the  gradual  de- 
pression of  the  land  which  is  thus  embanked  is  caused  only  by  the  subsi- 
dence of  the  alluvial  ground,  the  weight  of  the  dikes,  and  the  incessant 
passage  of  men  and  cattle.  However  great  may  be  the  importance  of 
these  combined  causes,  the  phenomena  of  subsidence  which  have  been 
noted  for  the  last  fifteen  centuries  are  considerable  enough  to  warrant  us 
in  accepting  M.  Elie  de  Beaumont's  hypothesis  as  to  the  depression  of  the 
ground  of  Holland.  If,  at  least,  we  may  judge  by  the  meari  level  both  of 
the  pavement  of  the  towns  and  of  the  fields  under  cultivation,  the  move- 
ment of  depression  is  most  rapid  at  the  mouths  of  the  rivers — the  Scheldt, 
the  Meuse,  and  the  Rhine.  At  Calais  the  streets  are  more  than  a  yard 
above  the  high  tide,  while  the  cultivated  ground  descends  to  the  limits  of 
the  tide.  At  Dunkirk  the  height  of  the  streets  is  not  more  than  23  inches, 
and  the  fields  are  plowed  at  a  level  of  a  yard  below  the  sea.  At  Fumes 
and  Ostend  the  streets  are  still  lower,  and  the  level  of  the  polders  is  al- 
ways sinking.  Near  the  mouths  of  the  Scheldt  it  is  11^  feet  below  the 
high  tide.  Farther  to  the  north  the  ground  gradually  rises,  but  the  streets 
of  Rotterdam  and  Amsterdam  are  lower  than  the  level  of  the  equinoctial 
tides.* 

All  the  adjacent  coasts — those  of  the  south  of  England,  and  of  Cornwall 
and  Yorkshire,  as  well  as  those  of  Hanover  and  Schleswig — likewise  afford 
certain  proofs  of  a  considerable  subsidence  by  their  submarine  peat-mosses, 
their  submerged  forests,  and  their  former  coasts  now  become  islands.  On 
the  western  coasts  of  Schleswig  the  subsidence  has  been,  on  the  average, 
*  Bourlot,  Variationa  de  Latitude  et  de  Climat. 

m 


548 


THE  EARTH. 


Fig.  224.  Coast  of  Friesland. 


13  feet  during  the  present  period.  In  this  locality,  at  the  bottom  of  the 
port  of  Husum,  there  was  discovered,  in  the  midst  of  a  submerged  fofest  of 
birches,  a  tomb  of  the  Age  of  Stone,  necessarily  dating  from  a  period  ante- 
rior to  the  subsidence  of  the  ground  on  which  it  stood.  On  the  eastern 
coasts  of  Schleswig  and  Holstein  many  phenomena  of  the  same  nature 
have  been  remarked,  which  can  only  be  explained  by  a  gradual  subsidence 
of  the  shore.  The  remains  of  an  old  castle  situated  at  the  mouth  of  the 
Schlei  are  covered  by  the  water.  Farther  on,  the  stumps  of  the  trees  of 
an  ancient  deer-forest  of  the  Middle  Ages  may  be  seen  under  the  water 
about  half  a  mile  from  the  shore.  In  the  Straits  of  Fehmara  are  found 
the  remains  of  an  ancient  wall ;  and,  lastly,  near  Travemunde,  two  blocks 
of  stone,  which  stood  on  the  beach  at  the  end  of  the  last  century,  are  now 
surrounded  by  water.*  These  are  facts  which  will  not  permit  us  to  at- 
tribute, solely  and  wholly,  to  the  action  of  the  waves  the  transformation 
of  several  peninsulas  into  islands,  and  lakes  by  the  sea-shore  into  arms  of 
the  sea.  According  to  John  Paton,  Denmark  and  Schleswig-Holstein  have 
lost,  since  the  year  1240,  an  area  of  about  1225  square  miles,  or  one  eight- 
eenth of  the  whole  surface  of  the  territory. 

Farther  to  the  east,  all  round  the  southern  basin  of  the  Baltic,  the  in- 
roads of  the  water  have  led  several  geologists  to  admit  that  the  ground 
of  these  countries  is  slowly  subsiding.  Rugen  is  broken  up  into  islets  and 
peninsulas ;  Bornholm  is  surrounded  by  submarine  forests,  one  of  which, 
according  to  Forchhammer,  is  26  feet  below  the  line  of  the  shore.  Other 
submerged  forests  fringe  the  coasts  of  Pomerania  and  Eastern  Prussia. 
*  Von  Maack, i>as  urgeschichtUche  Schleswig-Holsteinische  Land,l860. 


DEPRESSION  OF  FRIESLAND  AND  DENMARK.  549 

The  islands  of  WoUin  and  TJsedom,  situated  in  front  of  the  mouths  of  the 
Oder,  have  gradually  been  eaten  away  by  the  waves.  The  sandy  bar 
which  impedes  the  entrance  to  the  port  of  Swinemunde  used  to  form  a 
peninsula  of  Usedom,  indeed,  during  historical  periods.*  Lastly,  accord- 
ing to  the  evidence  of  Barth,  the  point  of  Samland  has  been  overwhelmed 
by  the  water,  as  may  be  easily  recognized  by  the  fact  that  the  church  of 
St.  Adalbert,  which  was  built  about  the  end  of  the  fifteenth  century  at  a 
point  4^  miles  from  the  sea,  is  now  found  in  a  state  of  ruin  only  100  paces 
from  the  beach. 

These  are  facts  which  can  not  be  questioned.  Nevertheless,  we  are  not 
3'et  warranted  in  considering  them  as  positive  proofs  of  the  subsidence  of 
the  ground,  for  Voigt,  and  several  other  scientific  observers,  class  them 
among  the  simple  phenomena  of  ei'osion  and  deposit.  However  this  may 
be,  there  are  very  strong  reasons  for  considering  the  channel  and  the 
southern  waters  of  the  North  Sea  and  the  Baltic  as  a  trench  of  depression, 
an  elongated  valley  1100  miles  in  extent,  separating  the  area  of  upheaval 
of  Northern  Europe  from  that  which  is  bounded  at  its  northern  extremity 
by  the  coasts  of  Poitou. 

*  Anton  von  Etzel,  Die  Ostsee. 


550 


THE  EARTH. 


CHAPTER  LXXXIV. 

UPHEAVAL    OF    THE    COASTS    OF    CHILI    AND    PERU. — PROBABLE    DEPRESSION 

OF  THE   COASTS   OF   LA  PLATA  AND   BRAZIL. COASTS   OF   NORTH  AMERICA 

AND   GREENLAND. 

The  New  World — that  double  continent,  the  architecture  of  which  is 
distinguished  by  general  features  of  such  simple  grandeur — likewise  ex- 
hibits a  remarkable  regularity  in  the  action  of  its  gentle  oscillations.  The 
latter  are  much  more  easy  to  study  than  the  movements  of  the  more  in- 
dented and  irregular  peninsulas  of  Europe,  and  are  also  better  known : 
since  the  epoch  when  the  illustrious  Darwin  noted  the  fact  that  a  great 
part  of  South  America  was  constantly  rising,  savants  and  observers  have 
only  had  to  confirm  the  result  of  his  investigations. 

It  is  principally  on  the  coasts  of  Chili  that  the  traces  of  the  general  up- 
heaval of  the  country  are  quite  self-evident.     Round  every  headland,  at 


Fig.  225.  Coasts  of  Puerto  Jsaii  Jorge. 


the  outlets  of  many  of  the  valleys  which  cut  deep  into  the  mountainous 
masses  on  the  coast,  former  sea-beaches  may  be  distinguished,  on  which 
shells  of  the  present  epoch,  like  those  of  the  creatures  which  are  now  liv- 
ing in  the  neighboring  bays,  are  scattered  about  or  even  heaped  up  in 
thick  layers.  These  beaches,  which  are  separated  from  one  another  by 
cliffs  or  escarpments  of  various  heights,  resemble  the  steps  of  a  gigantic 
staircase.  From  these  it  may  be  readily  seen  that  the  coast  was  not 
raised  by  any  uniform  movement,  and  that  intervals  ot  comparative  re- 
pose have  elapsed  between  each  of  the  stages  furnished  by  the  growing 
mass  of  rocks.  On  the  hills  of  the  Isle  of  Chiloe,  Darwin  found  heaps  of 
modern  shells  at  a  height  of  347  feet.  On  the  north  of  Conception,  several 
lines  of  level  cut  out  by  the  waves  during  the  present  period  are  found  at 
an  elevation  of  600  to  1000  feet.  Near  Valparaiso  these  levels  are  no  less 
than  1295  feet  above  the  level  of  the  sea;  but  north  of  this  town  they  be- 
come lower.  At  Coquimbo  they  scarcely  exceed  110  feet,  and  on  the  fron- 
tier of  Bolivia  they  are  only  65  to  80  feet  above  the  sea-level.  Thus  the 
rising  action  of  the  rocks  is  especially  developed  in  those  regions  of  the 


ELEVATION  OF  THE  COASTS  OF  CHILI  AND  PERU.  551 

sea-coast  which  are  in  the  same  latitude  as  the  loftiest  summits  of  the 
Chilian  Andes — Aconcagua,  Maypu,  and  Tupungato.  We  may  infer  from 
this  that  these  high  peaks  indicate  the  axis  of  the  portion  of  the  upheaved 
crust,  and  that  the  mountains  themselves  tend  to  increase  more  rapidly 
than  the  plateaux  and  shores  situated  below  them.  In  fact,  in  Chili,  as  in 
Norway,  the  terraces  which  overlook  former  bays  or  the  mouths  of  val- 
leys are  not  horizontal,  as  they  appear  to  be ;  they  rise  gradually  toward 
the  mountains,  and  increase  in  height  as  they  recede  from  the  present 
coast.  The  upheaving  force  acts,  therefore,  with  more  energy  under  the 
Chilian  Andes  than  under  the  rocks  of  the  adjacent  coast.  The  white 
summits  are  gradually  mounting  up  into  the  sky. 


:;m  ft 


Fig.  22fi.  Coasts  of  Coquimbo. 

Trigonometrical  measurements  carried  on  for  a  long  series  of  years  will 
some  day  enable  us  to  recognize  this  increase  in  the  giants  of  Chili,  and 
their  upward  progress  into  the  regions  of  eternal  snow ;  but,  up  to  the 
present  time,  the  only  calculations  which  have  been  made  on  the  subject 
of  the  rapidity  of  the  upheaval  of  the  Andes  are  based  merely  on  the  study 
of  the  sea-shores  extended  at  their  base.  Comparing  the  present  state  of 
things  with  the  evidence  derived  from  history,  Darwin  proves  that,  during 
seventeen  years,  between  1817  and  1834,  the  ground  at  Valparaiso  has 
risen  10  feet  T  inches,  or  about  7^  inches  a  year.  This  rather  rapid  move- 
ment was  preceded  by  a  state  of  comparative  inaction,  for,  from  1614  to 
1817,  more  than  two  centuries,  the  elevation  of  the  shore,  as  proved  by  an 
examination  of  the  localities,  certainly  could  not  have  exceeded  5  feet  11 
inches.  At  Coquimbo,  Conception,  and  the  island  of  Chiloe,  the  emerge- 
ment  of  the  shore  has  taken  place  still  more  slowly.  But,  however  im- 
perceptible the  phenomenon  may  be,  it  is  none  the  less  taking  place  during 
the  course  of  ages,  and  must  ultimately  completely  change  the  aspect  of 
the  American  coasts.  Several  ancient  ports  which  were  once  frequented 
are  now  inaccessible ;  other  harbors  have  been  formed,  thanks  to  the  fresh 
protecting  points  which  have  emerged.  Numerous  islands,  always  desig- 
nated by  the  Indian  nai^e  huapi,  have  become  promontories. 

The  indications  of  a  gradual  upheaval  are  equally  visible  on  the  coasts 
of  Bolivia  and  Peru.  In  the  eastern  zone  of  the  Desert  of  Atacama  the 
ground  is  covered  at  considerable  heights  with  shells  and  saline  efflores- 
cence, and  seems  as  if  it  had  been  abandoned  by  the  ocean  only  the  day 
before.  Above  Cobija,  Iquique,  and  several  other  coast  towns,  stages  are 
marked  out  similar  to  those  at  Coquimbo,  and,  like  the  latter,  were  once 
washed  by  the  water  of  the  Pacific.  In  front  of  Arica  the  sea  has  receded 
165  yards  in  the  space  of  forty  years,  and  the  merchants  of  the  town  have 
been,  in  consequence,  compelled  to  lengthen  their  landing-stage.     But  in 


552  THE  EARTH. 

front  of  Callao,  on  one  of  the  clifis  of  the  island  of  San  Lorenzo,  a  most  in- 
teresting proof  has  been  found  of  the  elevation  of  the  shore  during  the  pe- 
riod it  was  inhabited  by  man.  At  a  height  of  85  feet  above  the  sea,  Dar- 
win discovered,  in  a  bed  of  modern  shells  deposited  on  a  terrace,  roots  of 

1200  ft.  •  

"'K^»S'*'^^V        639  ft.  


Fig.  227.  Valley  of  Eio  Sauta  Cruz. 

sea-weed,  bones  of  birds,  ears  of  maize,  plaited  reeds,  and  some  cotton 
thread  almost  entirely  decomposed.  These  relics  of  humali  industry  ex- 
actly resemble  those  which  are  found  in  the  huacas  or  burial-places  of  the 
ancient  Peruvians.  There  can  be  no  doubt  that  the  island  of  San  Lorenzo, 
and  probably  the  whole  of  the  adjacent  coast,  have  risen  at  least  80  feet 
since  the  Red  Man  inhabited  the  country.  It  nevertheless  appears  that  in 
our  days  the  ground  on  which  Callao  stands  has  again  sunk,  for  the  place 
where  the  ancient  tOAvn  stood  is  now  in  great  part  under  water.  This  de- 
pression is  doubtless  merely  local,  and  only  temporarily  affects  the  gen- 
eral ascending  movement  of  the  coast ;  for  farther  to  the  north,  at  Colon 
and  at  Santa  Marta,  and  several  other  points  of  the  coast  of  New  Granada, 
the  ground  has  visibly  risen  since  Europeans  first  landed  on  the  continent. 
By  admitting,  however,  that  Callao  forms,  in  fact,  the  northern  limit  of  the 
area  of  upheaval,  it  results  that  the  mass  raised  presents  from  north  to 
south  a  length  of  at  least  2480  miles.  It  is  almost  equal  to  the  distance 
from  London  to  Tobolsk. 

The  movements  of  the  eastern  coast  of  South  America  which  are  at  pres- 
ent going  on  have  not  been  recognized  so  certainly  as  those  of  the  west- 
ern shore,  doubtless  on  account  of  the  extremely  slow  rate  at  which  they 
proceed.  An  investigation  of  geological  facts  proves  that  the  ground  rose 
during  the  post-Pliocene  period — that  is,  during  the  age  of  shell-fish  still 
existing,  and  of  the  great  animals  which  were  the  contemporaries  of  our 
ancestors,  the  megatherium,  the  mastodon,  and  the  glyptodon.  The  Ar- 
gentine pampas  have  preserved  the  uniform  appearance  of  the  ocean  which 
once  covered  them.  The  parallel  terraces  of  Patagonia,  extending  for 
more  than  500  miles,  vary  but  a  few  yards  in  height  along  all  the  points 
of  their  immense  development,  and  the  arms  of  the  sea  which  wind  in  be- 
tween the  terminal  promontory  of  America  and  the  Tierra  del  Fuego  re- 
tain all  their  ancient  outlines.  At  the  present  time  this  portion  of  the 
continent  appears  to  be  oscillating  in  a  contrary  direction,  and  to  be  sink- 
ing by  an  imperceptible  movement  toward  the  level  of  the  Atlantic.  At 
the  foot  of  the  high  cliffs  of  Patagonia  the  sea  is  incessantly  increasing  at 
the  expense  of  the  continent,  and,  although  the  breakers  are  not  possessed 
of  force  sufficient  to  demolish  the  rocky  beds  for  more  than  13  to  16  feet 
below  the  surface,  the  depth  of  the  sea  nevertheless  augments  with  an 


OSCILL^ONS  OF  SOUTH  AMERICA.  553 

even  slope,  iu  proportion  to  the  distance  from  the  shore,  even  over  the  site 
of  the  foi-mer  cliffs.  The  bed  of  the  sea  must  therefore  be  sinking,  and 
with  it  the  enormous  mass  of  the  plateaux  which,  during  the  recent  period 
of  the  great  mammals,  rose  with  such  marvelous  regularity. 

On  the  coast  of  Brazil,  especially  at  Bahia,  various  recent  depressions 
seem  to  indicate  that  there  also  the  surface  of  the  continent  is  regularly 
sinking.  The  ascertained  facts  were  not,  however,  sufficiently  numerous 
to  justify  any  categorical  assertion,  until  Professor  Agassiz,  in  company 
with  some  other  geologists,  undertook  his  recent  exploration  of  the  River 
of  the  Amazons.  In  the  first  place,  he  verified  the  remarkable  fact  that, 
in  spite  of  the  enormous  quantity  of  sediment  drifted  down  by  its  current, 
this  river  does  not  form  any  deposits  at  its  mouth.  Instead  of  throwing 
out  into  the  ocean  a  long  peninsula  of  alluvium,  like  that  of  the  Mississip- 
pi, or  at  least  forming,  beyond  the  regular  coast-line,  a  delta  similar  to 
those  of  the  Rhone,  the  Nile,  or  the  Po,  the  Amazon,  on  the  contrary, 
widens  out  in  a  large  gulf  toward  the  sea,  and,  in  the  great  estuary,  it  is 
difficult  to  say  exactly  where  the  mouth,  properly  so  called,  commences. 
The  banks  of  the  river,  and  the  islands  which  lie  in  its  outlet,  are  not  com- 
posed of  alluvium  brought  down  by  the  current  of  fresh  water,  but  are  all 
formed  of  rock  with  horizontal  strata  deposited  by  the  water  of  the  river 
at  some  former  epoch,  and  long  since  solidified.  Thus,  in  the  contest  which 
takes  place  in  the  estuary  of  the  Amazon,  as  in  every  other  river-mouth, 
between  the  currents  of  fresh  and  salt  water,  between  the  fluviatile  allu- 
vium and  the  erosions  of  the  sea,  the  latter  always  prevail.  Instead  of  en- 
croaching on  the  ocean,  the  valley  of  the  Amazons  has  been  invaded  by 
the  latter  for  at  least  300  miles ;  for  the  geological  study  of  the  ground 
on  the  two  shores  of  the  estuary  proves  that  rocky  layers,  exactly  similar 
to  those  farther  up  stream,  exist  on  the  coast  as  far  as  the  valleys  of  the 
Itapicuru  and  the  Parnahyba.  These  two  rivers  once  fell  into  the  Ama- 
zon, but,  in  consequence  of  the  erosion  of  their  shores  and  those  of  the 
great  current  which  they  joined,  the  sea  has  advanced,  as  it  were,  to  meet 
them,  and  they  have  thus,  by  degrees,  become  entirely  independent  of  the 
Amazon  system.  In  a  similar  way,  the  stream  of  the  Tocantins  is  now 
only  indirectly  connected  with  the  great  central  river,  and  sooner  or  later 
it  must  ultimately  become  isolated,  as  the  Itapicuru  and  the  Parnahyba 
already  are.  The  action  of  erosion,  caused  doubtless  by  a  constant  sink- 
ing of  the  ground,  is  still  continuing.  The  shores  are  noticed  to  recede  all 
round  the  estuary  at  Maranhao,  at  Piauhy,  at  Macapa,-  and  on  the  coasts 
of  Marajo.  On  the  shores  of  the  latter  island,  near  Soure,  a  wide  gulf,  into 
which  flows  the  Igarape  Grande,  nas  recently  been  formed  across  a  forest 
for  a  space  of  more  than  18  miles  from  bank  to  bank.  The  rocks  in  the 
vicinity,  which  once  rose  above  the  sea-level,  are  gradually  becoming  cov- 
ered. At  Bragan^a,  the  bay,  which  used  to  advance  scarcely  a  mile  and  a 
half  into  the  land,  now  penetrates  for  nearly  five  miles.  The  light-house 
of  Vigia,  which  was  built  at  some  distance  from  the  sea,  was  a  very  few 
years  afterward  washed  by  the  waves.     A  signal-mast,  which  was  set  up 


554  TEE  EARTH.      ^ 

in  December  out  of  reach  of  the  water,  was  surrounded  by  the  sea  in  the 
June  following.  Facts  of  this  kind  render  very  probable  the  existence  of 
a  see-saw  movement,  which  is  upheaving  all  the  western  coast  of  America 
from  the  island  of  Chiloe  to  Callao,  and  depressing  the  eastern  side  of  the 
Argentine  Andes,  of  Patagonia,  and  Brazil.  Thus  a  large  portion  of  the 
South  American  continent  is  constantly  gaining  on  one  side  that  which  it 
loses  on  the  other,  and  is  gradually  making  its  way  through  the  ocean  in 
a  westward  direction.  Agassiz  assigns  to  this  phenomenon  of  displace- 
ment a  very  ancient  origin,  for  in  his  view  the  Antilles,  which  once  formed 
the  isthmus  joining  the  two  Americas,  have  been  gradually  submerged, 
and  the  rivers  of  Guiana,  once  tributaries  of  the  Orinoco,  have  become  in- 
dependent rivers. 

In  North  America  the  vertical  oscillations  of  the  ground  have  not  been 
recognized  over  so  considerable  a  length  as  in  the  southern  continent,  but 
the  few  observations  which  have  been  already  made  on  some  points  of  the 
coast,  in  California  as  well  as  round  the  Gulf  of  Mexico,  render  the  hypoth- 
esis very  probable  that  a  general  upheaval  is  taking  place,  to  which  one 
of  the  parallel  chains  of  the  Rocky  Mountains,  or  of  the  Sierra  Nevada, 
serves  as  axis.  The  shore-belt  of  Tamaulipas  and  Texas  increases  ^o  rap- 
idly in  width,  not  only  because  the  south  wind — which  here  blows  almost 
the  whole  year  through — throws  up  a  large  quantity  of  sand,  but  also  be- 
cause the  ground  itself  is  rising.  During  eighteen  years — from  1845  to 
1863 — the  shores  of  the  Bay  of  Matagorda  have  risen  11  to  22  inches.  In 
consequence  of  this  gradual  increase  in  the  land,  which  is  also  proved  by 
the  heaps  of  shells  left  far  from  the  shore,  it  has  been  found  necessary  to 
transfer  the  port  of  Indianola  to  Powderhorn,  a  place  4 J  miles  nearer  the 
entry.*  The  peninsula  of  Florida  is  likewise  being  upheaved  by  some  sub- 
terranean forces,  as  is  proved  by  the  coral-banks  which  are  rising  above 
the  level  of  the  sea.  Those  mysterious  elevations,  the  "  mud-lumps,"  which 
are  scattered  around  the  coast  near  the  mouths  of  the  Mississippi,  the  ori- 
gin of  which  M.  Thomassy  has  tried  to  explain  by  atti'ibuting  them  to  the 
pressure  of  subteiTanean  water,f  also  appear  to  testify  in  favor  of  a  gen- 
eral upheaval  of  the  region. 

The  eastern  side  of  North  America  is  not  rising  uniformly,  for,  although 
it  is  proved  that  the  coasts  of  Labrador  and  Newfoundland  are  being 
slowly  elevated,  it  is  also  proved  that  other  regions  are  sinking.  Lyell 
has  ascertained  that  certain  parts  of  the  coasts  of  Georgia  and  South  Car- 
olina are  subject  to  a  movement  of  subsidence,  and  it  is  in  consequence  of 
a  gradual  depression,  no  less  than  from  a  constant  action  of  erosion,  that 
Sullivan  and  Morris  Islands,  at  the  entrance  of  Charleston  Roads,  are  inces- 
santly diminishing  in  area.  In  like  manner,  all  that  portion  of  the  coast 
which  has  as  its  centre  the  Bay  of  New  York,  and  is  bounded  on  the  north 
by  Cape  Cod,  and  on  the  south  by  Cape  Hatteras,  has  gradually  sunk  un- 
der the  water  of  the  Atlantic ;  and  the  subsidence  has  not  yet  ceased,  at 
least  as  regards  the  coasts  of  New  York  and  New  Jersey.     An  isle  which, 

*  Adolf  Donai,  Mittheilungen  non  Petermann,  April,  1864,  f  Vide  above,  p.  250. 


MO  VEMENTS  OF  THE  COASTS  OF  NORTH  AMERICA.  555 

on  a  map  of  1649,  is  marked  down  as  possessing  an  area  of  290  acres,  is  at 
the  present  day  not  more  than  100  square  yards  in  extent  at  low  tide,  and 
at  high  tide  is  %ntirely  submerged.  If  we  are  to  put  faith  in  tradition, 
the  Straits  of  Hell  Gate,  which  form  the  entry  to  the  port  of  New  York, 
are  of  recent  origin.  Two  centuries  ago  the  natives  related  to  the  Dutch 
colonists  established  in  the  island  of  Manhattan  that,  at  the  time  of  the 
fathers  of  their  grandfathers,  it  was  possible  to  cross  dry-shod  from  one 
bank  to  the  other,  and  that  the  sea  only  penetrated  into  the  straits  at  the 
time  of  the  great  equinoctial  floods.  The  land-surveyors  employed  on  the 
survey  have  calculated  that  the  shores  of  the  Bay  of  Delaware  lose,  on  the 
average,  nearly  eight  feet  every  year.  As  far  as  it  is  possible  to  judge 
from  the  observations  made  since  the  colonization  of  the  country,  the  slow 
subsidence  of  this  portion  of  the  American  coast  maybe  estimated  at  23^ 
inches  every  century.* 

In  the  vast  island  of  Greenland,  which  lies  in  the  axis  of  North  America, 
the  progress  of  gradual  subsidence,  succeeding  to  a  period  of  upheaval, 
appears  to  be  much  more  rapid.  For  a  long  time  the  Esquimaux  have 
been  acquainted  with  this  phenomenon,  and  the  Danish  colonists  on  the 
western  coast  have  also  been  enabled  to  verify  the  facts  since  the  last 
century  by  noticing,  for  a  length  of  more  than  620  miles,  rocks,  advanced 
promontories,  and,  indeed,  their  own  dwellings,  gradually  disappearing 
under  the  inroads  of  the  water.  According  to  Wallich,  this  receding 
movement  is  still  going  on  as  regards  the  bed  of  the  sea  to  the  south  of 
Iceland,  and  the  sunken  land  of  Bass,  marked  out  on  all  the  old  charts,  has 
really  existed.  On  the  north  of  Greenland,  from  latitude  76°,  and  in  Gren- 
nell's  Land,  as  well  as  in  the  other  polar  regions  of  the  New  World,  the 
directly  contrary  phenomenon  is  taking  place.  In  his  voyage  undertaken 
to  discover  the  open  sea,  Hayes  ^oticed  on  all  the  coasts  the  existence  of 
ancient  sea-beaches,  which  had  gradually  risen  to  a  height  of  100  feet ; 
added  to  this,  all  the  cliffs  of  the  headlands  had  been  polished  up  to  this 
height  by  the  action  of  the  ice. 

*  Cook,  Geological  Survey;  Arnold  Guyot,  American  Journal,  March,  1861. 


/ 


556  .  ^-^-^  EARTH. 


CHAPTER  LXXXV. 

REEFS    OF    THE    SOUTH    SEA. — DARWIN's    THEORY    AS    TO    UPHEAVALS    AND 

DEPRESSIONS. 

The  study  of  shores  has  not  only  enabled  us  to  note  the  upheaval  and 
subsidence  of  great  continental  masses ;  it  has  also  made  known  to  savants 
the  oscillations  of  the  tracts  of  ocean,  for  the  numerous  islands  which  lie 
either  alone  or  in  groups  in  the  Indian  Ocean  have  served  as  evidence  to 
prove  the  movement  of  the  ground  on  which  they  stand.  Lines  of  erosion, 
parallel  terraces,  banks  of  modern  shells,  and  all  the  other  marks  of  the 
former  presence  of  the  water,  point  out,  in  each  of  the  islands  of  the  Pa- 
cific, as  well  as  on  the  coasts  of  Europe  and  the  New  World,  the  various 
upheavals  which  have  taken  place.  But,  in  addition,  most  of  these  islands 
are  surrounded  with  living  girdles  of  corals,  which  exactly  measure  all  the 
changes  in  level,  either  elevation  or  depression,  to  which  the  shores  are 
subject.  The  discovery  of  this  fact,  that  the  terrestrial  oscillations  are,  so 
to  speak,  rendered  visible  by  the  work  of  polypes,  is  doubtless  one  of  the 
most  important  achievements  of  modern  geography ;  and  it  is  to  the  pa- 
tient investigations  and  sagacity  of  Darwin  that  science  is  indebted  for  it. 
By  comparing  his  own  observations  with  those  of  the  explorers  who  pre- 
ceded him,  the  English  geologist  has  been  enabled  to  point  out,  just  as  if 
he  had  witnessed  them  with  his  own  eyes,  the  various  movements  which 
raise  or  depress  the  bed  of  the  ocean,  ov^r  an  area  as  great  as  that  of  the 
two  continents  of  Europe  and  Asia. 

All  the  travelers  who  have  crossed  the  South  Seas  have  been  struck 
with  astonishment  at  the  sight  of  the  reefs  raised  by  the  polypes  in  the 
midst  of  the  water.  Some  of  these  reefs  circle  round  at  a  distance  from 
islands,  or  even  archipelagoes ;  they  then  form  barriers  of  coral.  Others, 
situated  far  from  any  land,  are  distributed  in  the  shape  of  rings,  or  of 
more  or  less  elongated  crescents,  round  lagoons  or  bays  remarkable  for 
their  pale  green  water ;  these  are  the  atolls.  In  those  parts  of  the  ring 
where  the  constructions  of  the  polypes  and  madrepores  have  not  yet 
reached  the  surface,  the  waves  which  flow  over  the  submarine  bar  rise  in 
foamy  breakers;  in  other  parts  of  the  reef  there  are  Just  visible  above  the 
waves  rocks  of  a  dazzling  white  or  a  delicate  pink  hue.  Next  comes  a 
semicircular  range  of  islets,  like  Druidical  stones  set  up  by  giants  in  the 
open  sea.  Lastly,  upon  the  emerged  group  which  occupies  that  portion 
of  the  atoU  which  is  most  exposed  to  the  violence  of  the  waves  and  wind, 
cocoa-nut  trees  ^d  other  tropical  growths  wave  in  the  air,  either  in  mere 
groups  or  in  regular  groves.  This  is  the  most  common  form  of  the  reefs 
among  all  the  thousands  of  atoUs  which  are  dotted  over  the  South  Seas, 


ATOLLS,  OE  CORAL-REEFS. 


557 


12»3 


Fig.  228.  Keeling  AtolL 

When  these  coral-banks  have  not  as  yet  reached  the  surface,  their  position 
is  only  pointed  out  by  a  circle  of  breakers ;  those  that  have  attained  the 
last  stage  of  their  development  form  a  circular  grove,  which,  seen  from 
above,  would  look  like  a  coronal  of  leaves  floating  on  the  blue  water. 

How  have  these  wonderful  reefs  been  raised  ?  As  was  long  ago  proved 
by  Chamisso,  the  French  traveler,  the  ^lypes  love  to  build  in  the  midst 
of  water  which  is  breaking  into  foam ;  it  may  therefore  be  readily  under- 
stood that  wherever  a  submarine  bank  exists,  the  coral-reefs  assume,  like 
the  breakers  themselves,  a  more  or  less  annular  form.  But  in  spots  where 
the  sounding-line  reveals  no  shallows  near  the  atolls,  how  have  the  polypes 
been  able  to  raise  from  the  bottom  of  the  abyss  their  calcareous  habita- 
tions ?  In  order  to  explain  this  phenomenon,  scientific  men  once  hit  upon 
a  strange  hypothesis ;  they  looked  upon  every  cctoll  as  the  circumference 
of  a  crater,  which  the  submarine  forces  of  the  globe  had  raised  up  to  a  dis- 
tance of  a  few  yards  from  the  surface,  so  as  t^  form  a  base  to  the  opera- 
tions of  the  polypes.  Although  this  explanation  might  be  true  enough 
for  a  very  limited  number  of  atolls,  it  would  be  incomprehensible  how 
thousands  and  thousands  of  volcanoes  should  have  been  elevated  to  the 
same  height  below  the  level  of  the  sea.  Nor  could  it  be  understood  why 
the  craters  of  these  supposed  volcanoes  should  so  often  assume  very  elon- 
gated forms.  Lastly,  it  would  be  impossible  to  conceive  why,  taking  into 
account  the  multitudes  of  annular  reefs,  of  which  several  archipelagoes 


i58 


THE  EARTH. 


are  composed,  and  especially  the  double  range  of  the  Maldives,  465  miles 
long  by  50  miles  broad,  no  a^o^has  ever  distinguished  itself  by  an  erup- 
tion of  lava  or  ashes. 


Fig.  229.  Atoll  of  Ebon. 

The  form  of  these  reefs,  therefore,  has  no  connection  with  volcanic  phe- 
nomena, properly  so  called,  and,  like  so  many  other  facts  in  the  terrestrial 
history,  can  only  be  explained  by  being  attributed  to  slow  movements  of 
the  surface.  The  subsidence  of  the  bed  of  the  sea  will  account  for  the 
formation  of  atoUs  and  barriers  of  reefs ;  on  the  other  hand,  a  gradual  ele- 
vation of  the  ground  expkiins  the  position  of  the  corals  Avhich  fringe  the 
shore  at  a  certain  height  above  the  waves.  Thus,  whether  they  rise  or 
sink,  the  reefs  formed  by  the  polypes  may  serve  as  a  measure  of  the  ver- 
tical oscillations  to  which  continental  coasts,  islands,  and  even  the  abysses 
of  the  sea  are  subject. 

It  is  easy  enough  to  verify  the  movement  of  land  which  is  rising,  as,  in 
this  case,  we  see  the  banks  of  coral  resting  upon  the  beach,  and  sprinkling 
with  their  debris  that  portion  of  the  shore  which  is  above  the  level  of  the 


OSCILLATIONS  OF  THE  SEA-BOTTOM. 


559 


sea.  Often,  too,  the  channels  can  be  distinguished  which  once  separated 
them  from  the  coast,  and  on  the  high  ground  of  several  islands  calcareous 
banks  are  found,  which  evidently  owe  their  origin  to  polypiers.  With  re- 
gard to  the  coral  islands  which  are  not  included  in  the  area  of  upheaval, 
they  are  surrounded  by  annular  reefs,  constructed  in  the  midst  of  the 
water  at  some  distance  from  the  shore.  When  this  distance  is  but  small, 
and  the  coral  banks  are  not  very  thick,  theae  is  nothing  to  prove  that  the 
level  of  the  coast  has  changed  ;  for  the  observations  ofsava7its  prove  that 
polypes  can  live  and  build  their  rocky  habitations  at  a  depth  of  from  100 
to  150  feet.  Generally,  however,  the  walls  of  coral  and  calcareous  sand, 
which  form  the  outer  sides  of  the  reef,  descend  much  lower.  Most  of  them 
lie  on  slopes  composed  of  their  own  debris,  and  are  immersed  in  the  sea  at 
a  slope  of  45°  to 'depths  of  several  hundreds  and  even  thousands  of  feet. 


Fig.  230.  Isle  of  Vanikoro. 

• 

It  is  evident  that  in  a  case  like  this  the  bed  of  the  ocean  must  have  sub- 
sided. The  polypes  commenced  their  work  of  construction  a  few  yards 
below  the  surface,  and  then,  in  proportion  as  the  ground  sank  on  which 
their  coral  edifice  stood,  they  continued  to  build  upward  and  upward,  in 
order  to  approach  the  light.  The  mountainous  islands,  which  they  sur- 
round with  their  reefs,  gradually  diminish  in  height,  leaving  between  them- 
selves and  the  barrier  of  coral  a  channel  of  increasing  width  and  depth. 
The  time  is  approaching  when,  first  having  been  reduced  to  the  state  of 
islets,  they  will  become  divided  into  isolated  peaks,  which  one  after  the 
other  will  be  submerged,  and  disappear  in  the  sea.     Then  all  that  remains 


560 


THE  EARTH. 


will  be  an  atoll^  inclosing  within  its  inci'easing  walls  a  lagoon,  in  which 
calcareous  debris  is  slowly  gathered ;  narrow  beaches  and  reefs,  like  the 
pieces  of  wreck  still  floating  above  a  foundering  ship,  surround  the  spot 
where  the  island  has  been  swallowed  up.  The  natives  of  the  atolls  ol 
Ebon  relate  that  they  have  heard  their  fathers  say  that  an  elevated  island, 
the  hills  of  which  were  shaded  by  cocoa-nut  trees  and  bread-fruit  trees, 
once  occuj)ied  the  greater  p^t  of  the  lagoon.  The  isles  disappeared,  but 
the  reefs  are  still  maintained  just  above  the  level  of  the  water,* 

When  the  subsidence  of  a  whole  archipelago  of  submarine  peaks  takes 
place  slowly  and  regularly,  it  may  often  happen  that  the  sea,  striking 
forcibly  against  the  outer  walls  of  the  reefs,  breaks  this  barrier,  and  hol- 
lows out  for  itself  a  free  passage  across  the  central  lagoon.  Then  the 
banks  of  coral  rise  in  the  midst  of  the  breakers  on  both  sides  of  the  newly- 
formed  channel,  and  the  original  atoll  is  thus  divided  into  two  annular 
isles.  In  proportion  as  thts  submarine  mass  sinks,  other  ruptures  of  the 
same  kind  take  place  in  each  of  the  isolated  fractions  of  the  atoU^  and  the 
archipelago  of  reefs  is  ultimately  composed  of  a  considerable  number  of 
islets,  which,  in  their  turn,  are  also  broken  up.  In  this, way  are  formed 
these  wonderful  groups  of  annular  banks  arranged  in  immense  ovals. 


Fig.  231.  Section  of  Isle  Vanikoro. 

The  Atoll  Ari  of  the  Maldives  is  an  example  of  this  astonishing  forma- 
tion of  coral  islands.  If  we  could  represent  in  a  drawing  the  shapes  that 
the  ensemble  of  the  groups  has  successively  assumed  during  the  course  of 
centuries,  we  should  obtain  a  series  of  curves  similar  to  those  which  geog- 
raphers avail  themselves  of  to  delineate  the  slopes  of  a  mountainous 
group.  Sometimes,  however,  the  movement  of  a  depression  is  so  rapid 
that  the  sea  does  not  confine  itself  to  opening  channels  here  and  there 
across  the  atolls.  The  coral  insects  do  not  build  fast  enough  to  maintain 
their  dwellings  on  a  level  with  the  surface ;  they  gradually  perish,  and 


Fig.  232.  Growth  of  Coral  on  a  Mountain  slowly  sabeiding, 
*  Doane,  Nautical  Magazine,  Sept. ,  1 8G3. 


ATOLL    ARI 


PL.XXh'. 


?o:-w.Eoj<i.  uf  jMut 


<?       fSt 


Dhig-b(NK*ah 


"rSw" 


fioft^  ky  Irhara 


-};«i.pPPP.  8fBRQri?'=,R^    N^W  YORK 


OSCILLATIONS  OF  THE  SEA-BOTTOM. 


561 


th^gdoUs,  which,  layer  by  layer,  have  been  raised  by  innumerable  genera- 
tion of  constructors,  disappear,  and  form  annular  shoals.  Of  this  kind  is 
the  great  bank  of  Chagos,  south  of  the  Maldives,  which  the  sounding-line 


Fig.  233.  Great  Bank  of  Chagos. 


shows  to  have  once  been  one  of  the  largest  atolls  in  the  Indian  Ocean.  In 
the  group,  indeed,  of  the  Maldives,  several  islets,  whicli  were  recently  in- 
habited and  green  with  vegetation,  are  now  slowly  being  swallowed  up 
beneath  the  surface  of  the  water.* 

*  Darwin,  Coral  Reefs, 

Nn 


502  THE  EARTH. 


CHAPTER  LXXXVI. 

THE    GREAT  AREAS    OF   UPHEAVAL   AND   DEPRESSION. — MOBILITY   OP  THE 
SO-CALLED   RIGID   CRUST   OF   THE    EARTH. 

Owing  to  the  evidence  which  is  furnished  by  coral  reefs,  which  evidence, 
however,  is  supplemented  at  a  large  number  of  points  by  other  indications, 
it  is  now  possible  to  fix  almost  exactly  the  limits  of  the  areas  both  of  up- 
heaval and  subsidence,  which  divide  between  them  the  hemispheres  in- 
cluded within  the  coasts  of  South  America  and  Africa.  While  the  group 
of  the  Sandwich  Islands  is  rising,  as  if  it  were  still  subject  to  the  forces 
which  are  elevating  the  American  continent,  a  gradual  subsidence  may  be 
noticed  in  rtie  archipelagoes  of  the  central  basins  of  the  South  Seas,  tWI 
Bass  and  Society  Islands,  and  also  the  Gilbert,  Marshall,  and  Caroline  Isl- 
ands ;  in  one  word,  all  this  "  milky  way"  of  islands,  islets,  and  reefs,  which 
extends  diagonally  across  the  Pacific  for  a  length  of  more  than  9000  miles, 
and  with  an  average  width  of  1200  miles.  These  islands  are  the  remnants 
of  a  former  continent,  which  has  sunk  down,  with  the  people  who  inhabited 
it.  Since  the  first  European  navigators  visited  these  seas,  several  islands 
have  disappeared,  and  others,  such  as  Whit-Sunday  Island,  have  consider- 
ably diminished  in  size. 

In  a  parallel  line  with  this  great  area  of  depression,  which  is  at  least 
twice  as  large  as  Europe,  lies  a  wave  of  upheaval  which  coincides  with 
the  semicii'cie  of  volcanoes  running  round  the  western  side  of  the  basin 
of  the  South  Sea.  New  Zealand,  which  is  situated  on  the  southern  end 
of  this  rising,  and  is  based  on  a  long  furrow  of  fire,  is  rising  in  certain 
places  so  considerably,  that  English  colonists,  who  have  only  arrived  there 
a  few  years,  have  been  able  to  notice  that  the  headlands  increase  in  height, 
and  that  banks  of  rocks  are  gradually  obstructing  the  entrance  of  the 
ports.  At  the  commencement  of  the  present  geological  epoch,  the  moun- 
tains of  Zealand  were  at  least  1900  feet  lower  than  they  now  are,  and  the 
ice-floes,  from  a  continent  situated  to  the  east,  floated  with  their  load  of 
erratic  rocks  on  to  the  incipient  islets,  and  were  there  stranded.  But  since 
that  time  the  New  Zealand  Alps  have  risen  ten  successive  times,  as  is 
proved  by  the  ten  terraces  lying  in  stages  on  the  sides  of  the  mountains,* 
Even  at  the  present  day  the  latter  are  still  increasing.  In  ten  years  the 
shores  at  Lyttleton  have  risen  three  feet.  The  New  Hebrides,  the  Salomon 
Islands,  the  northern  and  western  coasts  of  New  Guinea,  the  numerous  isl- 
ands which  compose  the  great  Sunda  Archipelago  (which  latter  are  proved 
by  their  altogether  Asiatic  fauna,  as  studied  by  Wallace,  to  have  once 

*  Julius  Haast.  F.  von  Hochstetter  also  asserts  that  the  eastern  coast  is  being  upheaved, 
but  he  thinks  that  the  western  coast  has  sunk,  and  that  the  axis  of  a  see-saw  movement  passes 
through  the  two  islands. 


AREAS  OP  UPHEAVAL  AND  DEPRESSION. 


563 


formed  a  portion  of  the  neighboring  continent),  are  all  now  rising,  after 
having  quite  recently  subsided,  and  banks  of  coral  emerging  from  the  sea 
are  incessantly  being  added  to  the  shores. 

At  the  angle  of  the  Asiatic  continent  the  wgive  of  elevation  divides  in 
a  fork,  so  as  to  run  round  the  Chinese  Sea,  which  is  bordered  by  the 
gradually-depressed  coasts  of  Cochin-China  and  Tonquin.  To  the  north 
the  upheaved  region  is  continued  toward  America  by  the  Philippine,  For- 
mosa,* Liou-Kieou  Islands,f  and  Japan ;  that  is,  all  the  islands  from  Borneo 
to  Kamtschatka,  through  which  passes  the  fissure  of  eruption  of  the  vol- 
canoes of  the  Western  Pacific.  Quite  recently  Russian  travelers  have  dis- 
covered, on  the  coast  of  the  great  island  Saghalien,  heaps  of  modern  shells, 
lying  not  far  from  the  shore,  on  beds  of  marine  clay,  and  also  former  bays, 
which  are  now  convei'ted  into  lakes  or  salt  marshes.  In  like  manner,  it 
has  been  proved  that  the  regions  of  the  Amoor  are  gradually  being  up- 
heaved ;  for,  in  order  to  maintain  its  level,  the  river  has  constantly  to 
hollow  out  its  bed  between  the  clifis,  and  on  the  plateau  by  the  river-side, 
semicircular  sheets  of  water  may  still  be  seen,  which  are  evidently  former 
windings  of  the  Amoor. 

On  the  west  of  the  Sunda  Archipelago,  Sumatra,  fringed  on  its  eastern 
coasts  by  peninsulas  which  once  were  islands,  and,  indeed,  still  bear  the 
name  {poulo),  seems  to  be  the  starting-point  of  another  movement  of  up- 
heaval, which  embraces  all  the  coasts  situated  round  the  Bay  of  Bengal. 
The  Nicobar  and  Andaman  Archipelagoes  are  gradually  rising.  Ceylon 
is  likewise  rising ;  at  least  part  of  it,  as  is  proved  by  the  banks  of  coral 
lying  in  gradations  one  above  another  on  the  hills,  and  also  by  the  tradi- 
tions of  the  natives.  But  it  is  probable  that  the  extremity  of  the  isle  is 
undergoing  a  slight  see-saw  movement,  for  Adam's  Bridge,  the  chain  of 


Culf       of  Mana 


■77.1E  oCJeaiia- 


Fig.  234.  Bridge  of  Adam  or  Kama. 

shoals  which  joins  Ceylon  to  the  Coromandel  coast,  which,  too,  according 
to  the  legend,  formerly  served  as  a  road  to  the  triumphal  array  of  Hanou- 

*  Ferd.  de  Richthofen,  Zeitschrijt  der  Geologischen  Gesellscha ft,  rol.xu. 
t  Swinhoe,  North  China  Branch  of  Asiatic  Society,  No.  11,  May,  1869. 


564  T^^  EARTH. 

man,  the  monkey,  appears  to  have  once  been  a  perfect  isthmus.  Scarcely 
three  centuries  have  elapsed  since  the  peninsula  of  Rameseram,  whither 
thousands  of  Hindoos  went  every  year  in  pilgrimage,  has  become  detached 
from  the  main  land,  and  formed  an  islet,  like  the  ruins  of  a  fallen  pier.* 
Farther  to  the  north  there  has  been  an  upheaval.  If  we  may  put  faith  in 
the  Brahmin  legend,  Veruna,  the  god  of  the  sea,  two  thousand  three  hun- 
dred years  ago,  ordered  the  waves  to  abandon  the  low  plain  of  Malayala, 
which  extends  along  the  Malabar  coast  between  Mangalore  and  Cape  Co- 
morin.f  With  regard  to  the  basin  of  the  Lower  Ganges,  it  appears  to 
form  a  pari?  of  the  area  of  upheaval  of  the  Bay  of  Bengal,  and,  with  all 
its  southern  part,  to  be  gradually  rising ;  for  the  tributaries  of  the  river 
which  traverse  this  region  —  the  Coosy,  the  Mahanada,  and  the  Soane — 
are  constantly  shifting  their  mouths  farther  up-stream.  .The  last-named 
water- course  has  retreated  more  than  four  miles  during  the  last  eighty 
years.  According  to  Mr.  Ferguson,  at  the  confluence  of  the  Ganges  and 
Gogra  we  find  the  western  limit  of  the  wave  of  upheaval,  which  commences 
at  the  islands  of  New  Zealand,  8000  miles  away  toward  the  southeast. 

Almost  the  whole  of  the  space  occupied  by  Australia  and  the  Indian 
Ocean,  properly  so  called,  is  situated,  like  the  central- basin  of  the  Pacific, 
in  an  area  of  gradual  depression.  While,  from  New  Guinea  to  Sumatra 
and  the  Philippines,  a  new  continent  is  emerging  from  the  water,  the  old 
Australian  continent,  so  remarkable  for  its  fauna  and  its  flora,  which  seem 
to  belong  to  some  former  geological  period,  is  gradually  sinking  down,  to- 
gether with  the  surrounding  isles — the  Louisiade  Archipelago,  New  Cale- 
donia, and  the  reefs  of  the  Coral  Sea.  Up  to  the  present  time,  one  portion 
alone  of  Australia  is  known  to  be  experiencing  a  continuous  movement  of 
elevation — the  district  of  Hobson's  Bay,  near  Melbourne,  which,  according 
to  M  Becker,  is  rising  at  the  rate  of  about  four  inches  a  year.  Be  this  as 
it  may,  the  great  mass  of  the  continent  is  imperceptibly  sinking,  and  the 
polypes  which  surround  the  coast  are  compelled  to  heighten  their  reefs 
more  and  more.  J  The  Indian  Ocean,  to  the  west  of  Australia,  is  almost 
entirely  devoid  of  islands ;  but  all  those  that  emerge  from  the  depths  of 
the  sea  over  a  space  of  more  than  3700  miles  in  width  are  atolls,  which 
would  be  slowly  submerged  if  the  polypes  were  not  incessantly  building 
up  the  edges  of  the  reefs.  Among  these  islands  are  the  celebrated  Keel- 
ing Atoll,  which  Mr.  Darwin  has  studied  so  profitably  for  science,  and  the 
Maldive  Archipelago,  that  double  chain  of  submaiine  mountains,  every 
peak  of  which  is  crowned  with  a  coral  tiara  raised  above  the  water. 

Thus  the  space  which  extends  over  two  thirds  of  the  circle  of  the  globe, 
from  the  eastern  coast  of  America  to  the  western  shores  of  the  Indian 
jOcean,  presents  two  areas  of  upheaval  and  two  areas  of  subsidence  suc- 
ceeding one  another  from  east  to  west.  Next  to  the  American  continent, 
which  is  slowly  rising,  Ave  have  the  innumerable  low-lying  islands  of 
Oceania,  the  greater  part  of  which  would  have  long  ago  disappeared  if 

*  Ritter,  Erdkunde.  f  Duncan,  Asiatic  Researches,  voL  v. ;  Von  HofF,  Veranderungen. 

X  Gregory,  Philosophical  Society  of  Brisbane, 


ELEVATION  OF  PARTS  OF  OCEANIA  AND  AFRICA.  5^5 

it  were  not  that  the  labor  of  the  polypes  has  maintained  them  on  a  level 
with  the  waves.  Next,  there  is  developed,  in  a  vast  semicircle,  pointed 
out  from  afar  by  its  volcanoes,  a  large  zone  of  isles  and  sea-coasts  which 
are  gradually  rising,  as  if  to  replace  in  the  future  the  old  continent  of 
Australia.  Lastly,  the  same  causes  which  are  depressing  the  bed  of  the 
Central  Pacific  are  likewise  lowering  that  of  the  Indian  Ocean,  with  its 
shallows  and  its  reefs. 

Beyond  lies  the  enormous  mass  of  Africa,  the  coasts  of  which  have  not 
yet  been  explored  by  scientific  men,  except,  perhaps,  over  some  small  ex- 
tent. Nevertheless,  sufficient  observations  have  been  made  .to  warrant 
us  in  considering  Eastern  Africa  and  the  islands  adjoining  it  as  a  third 
wave  of  upheaval,  corresponding  with  those  of  America  and  the  Sunda 
Islands.  The  banks  of  coral  which  surround  Mauritius  Island,  Reunion, 
and  Madagascar,  and  those  which  border  the  African  coast  from  Mozam- 
bique to  Mombaze,  bear  witness  to  the  elevation  of  the  ground.  In  like 
manner,  the  southern  coasts  of  the  Red  Sea  still  exhibit  at  various  eleva- 
tions evident  traces  of  the  recent  presence  of  sea-water.  ,  Most  of  the  trav- 
eler who  have  visited  these  places,  Ferret  and  Gallinier,  RUppel,  Salt, 
Valencia,  and  Niebuhr,  have  been  struck  by  the  sight  of  reefs  emerged 
from  the  sea,  former  sea-beaches  white  with  salt,  and  bays  which  are  now 
left  far  inland,  and  are  converted  into  marshes.  Quite  recently  M.  Lejean 
has  recognized  the  fact  that,  by  the  upheaval  of  the  ground,  the  former 
port  of  Djeddah  is  completely  separated  from  the  sea,  and  has  become  a 
mere  lake ;  this  port,  at  the  time  of  Niebuhr,  was  still  accessible  to  ships 
of  small  tonnage.  The  inhabitants  of  the  coast  assert  that  both  the  bed 
and  the  shores  of  the  Red  Sea  change  eveiy  twenty  years. 

Not  far  from  the  Isthmus  of  Suez,  on  the  north,  the  slow  elevation  of 
the  groiind  is  replaced  by  a  contrary  movement ;  but  on  the  western  side 
it  is  not  yet  known  where  the  first  signs  are  to  be  found  of  any  rising  of 
the  ground.  The  observations  of  M.  Eugene  Robert  on  the  coast  of  Sene- 
gal would  perhaps  show  that  this  portion  of  Afiica  is  in  an  area  of  up- 
heaval. It  is,  however,  a  fact,  that  beyond  the  African  continent,  Madeira, 
St.  Helena,  and  probably  the  Canary  Islands,  the  remains  of  the  ancient 
Atlantis,  are  gradually  sinking  into  the  ocean.  All  these  facts  tell  in  favor 
of  the  hypothesis  according  to  which  the  equatorial  position  of  the  circum- 
ference of  the  globe  presents  three  waves  of  upheaval,  separated  from  one 
another  by  three  intervening  depressions.  The  centre  of  each  depression 
lies  in  the  middle  of  an  ocean ;  the  three  upheaved  regions  are  the  great 
Sunda  Archipelago,  a  kind  of  continent  in  process  of  formation,  and  the 
enormous  masses  of  Africa  and  America. 

As  will  be  understood,  these  regular  oscillations  must  take  plaq|^  obe- 
dience to  some  general  law  still  unknown,  although  none  the  less  certain. 
We  can  not  consider  them,  with  Berzelius,  to  le  nothing  but  mere  acci- 
dents, produced  by  the  subsidence  or  the  rupture  of  the  terrestrial  crust. 
Neither  must  these  regular  movements  be  confounded  with  volcanic  trem- 
blings, for  they  are  distinguished  from  the  latter  by  their  excessive  slow- 


5g6  THE  EARTH. 

ness,  as  well  as  by  their  character  of  generality.  Moreover,  all  these  facts, 
whatever  may  be  their  origin,  are  determined  by  causes  affecting  the  whole 
mass  of  the  planet.  If  earthquakes  have  their  tides,  as  is  said  to  be  proved 
by  the  greater  frequency  of  these  phenomena  at  the  time  of  the  full  and 
new  moon,  we  can  not  doubt  that  the  slow  oscillations  of  the  terrestrial 
envelope  also  have  their  regular  cycles.  Only  the  reason  of  these  secular 
tides  still  remains  unknown.  Must  we  seek  for  it  in  some  alteration  of  the 
physical  conditions  of  the  globe,  or  in  the  revolutions  of  some  astronom- 
ical period?  As  far  as  regards  these  points,  we  are  reduced  to  mere  hy- 
pothesis. Some  day  or  other,  when  scientific  men  have  observed  all  the 
lines  of  level  from  the  north  to  the  south  pole,  and  all  the  debris  which 
have  been  left  by  the  sea,  as  it  were  so  many  precise  measurements,  on 
sea-coasts  and  mountain-sides,  we  shall  be  able  to  exactly  specify  the  di- 
mensions of  each  wave  of  upheaval,  and  also  what  the  impulsive  force  is 
which  actuates  them.  We  shall  then  know  whether  the  regions  that  are 
elevated  are  always  equal  in  extent  to  those  that  subside,  and  whether 
the  surface,  like  that  of  every  vibrating  body,  presents  certain  "nodal 
lines,"  round  which  the  agitated  portions  arrange  themselves  in  rhythmical 
figures.  We  shall  know,  too,  whether  continents  and  seas,  alternately  ele- 
vated and  depressed  as  if  by  some  secular  tide,  are  slowly  shifting  their 
positions  round  the  planet,  assuming  therein  various  harmonic  forms.  Per- 
haps even  it  will  be  proved  that  in  the  bowels  of  the  earth  an  exchange 
of  solid  particles  is  taking  place  similar  to  the  circulation  of  the  aerial  and 
liquid  particles  of  the  atmosphere  and  the  ocean.  The  globe,  a  simple 
mass  as  it  is  of  condensed  gas,  is  not  entirely  congealed;  it  has  retained, 
like  every  other  body,  some  remains  of  its  former  fluidity,  and,  just  as  in 
a  lump  of  metal  coming  out  of  a  furnace,  the  particles  which  compose  it 
never  cease  to  turn  slowly  round  and  round  one  another. 

Be  this  as  it  may,  it  remains  an  unquestionable  fact  that  an  incessant 
movement  is  causing  an  undulation  in  the  so-called  rigid  crust  of  our 
globe.  The  continental  masses  are  still  elevated  through  a  long  course 
of  ages ;  next,  they  sink  only  to  rise  again  with  slow  and  majestic  oscilla- 
tions. Scandinavia,  which  is  at  present  rising,  sank  during  the  Glacial  pe- 
liod,  and  the  population  which  at  that  time  made  it  their  abode  were 
forced  to  abandon  their  valleys  step  by  step  as  they  became  converted 
into  fjords.  In  like  manner,  the  Chilian  Andes  and  the  mountains  of  New 
Zealand,  which  are  at  the  present  time  increasing  in  height,  previously 
sank  by  degrees,  the  former  8000  and  the  latter  5000  feet,  before  they  rose 
as  they  are  now  doing.  It  is  likewise  proved  that  at  a  great  number  of 
other  points — in  Peru,  in  Egypt,  in  North  America,  and  in  Greenland — 
changq^  of  the  same  nature  have  taken  place  during  the  present  era  of 
geological  history,  without  any  violent  revolution  having  thrown  the  earth 
into  confusion.  Continents  rise  and  sink  as  if  through  some  gentle  action 
of  respiration ;  they  move  in  long  undulations,  which  may  be  compared  to 
the  waves  of  the  sea ;  the  far-reaching  glance  of  science  can  already  trace 
out  these  undulations  through  the  long  lapse  of  centuries.     "  The  time 


~l 


OSCILLATIONS  OF  THE  CRUST  OF  THE  EARTH.  557 

will  come,"  says  Darwin, "  when  geologists  will  consider  the  quiescence  of 
the  terrestrial  crust  through  a  long  period  of  its  history  to  be  as  improba- 
ble as  an  absolute  calm  in  the  atmosphere  during  a  whole  season  of  the 
year."  t 

In  the  universe  every  thing  Is  changing  and  every  thing  is  in  motion, 
for  motion  itself  is  the  first  condition  of  vitality.  In  by-gone  days,  men 
who,  through  isolation,  hatred,  and  fear,  were  left  in  their  native  ignorance, 
and  filled  with  a  feeling  of  their  own  weakness,  could  recognize  in  all  that 
surrounded  them  nothing  but  the  Immovable  and  the  Eternal.  In  their 
i(^s  the  heavens  were  a  solid  vault,  a  firmament  on  which  the  stars  were 
fastened;  the  earth  was  the  firm,  unshaken  foundation  of  the  heavens,  and 
nothing  but  a  miracle  could  disturb  its  surface.  But  since  civilization  has 
connected  all  the  nations  of  the  earth  in  one  common  humanity — since 
history  has  linked  century  to  century — since  astronomy  and  geology  have 
enabled  science  to  cast  her  retrospective  glance  on  epochs  thousands  and 
thousands  of  years  back,  man  has  ceased  to  be  an  isolated  being,  and,  if  we 
may  so  speak,  is  no  longer  merely  mortal :  he  is  become  the  consciousness 
of  the  imperishable  universe.  No  longer  connecting  the  vitality  either  of 
the  stars  or  the  earth  merely  with  his  own  brief  and  fleeting  existence,  but 
comparing  it  with  the  duration  of  the  existence  of  his  own  race  and  of  all 
the  beings  who  have  lived  before  him,  he  has  seen  the  celestial  vault  re- 
solve itself  into  infinite  space,  and  has  recognized  the  earth  as  nothing  but 
a  little  globe  rotating  in  the  midst  of  the  ''  milky  way."  The  firm  ground 
which  he  treads  under  his  feet,  and  long  thought  to  be  immovable,  is  re- 
plete with  vitality,  and  is  actuated  by  incessant  motion ;  the  very  moun- 
tains rise  or  sink ;  not  only  do  the  winds  and  ocean-currents  circulate 
round  the  planet,  but  the  continents  themselves,  with  their  summits  and 
their  valleys,  are  changing  their  places,  and  are  slowly  traveling  round  the 
circle  of  the  globe.  In  order  to  explain  all  these  geological  phenomena,  it 
is  no  longer  necessary  to  imagine  alterations  in  the  earth's  axis,  ruptures 
of  the  solid  crust,  or  gigantic  subterranean  downfalls.  This  is  not  the 
mode  in  which  Nature  generally  proceeds ;  she  is  more  calm  andf  more 
regular  in  her  operations,  and,  chary  of  her  might,  brings  about  changes 
<jf  the  grandest  character  without  even  the  knowledge  of  the  beings  that 
she  nourishes.  She  upheaves  mountains  and  dries  up  seas  without  dis- 
turbing the  flight  of  the  gnat.  Some  revolution,  which  appears  to  us  to 
have  been  produced  by  a  mighty  cataclysm,  has  perhaps  taken  thousands 
of  years  to  accomplish.  Time  is  the  earth's  attribute.  Year  after  year 
she  leisurely  renews  her  charming  drapery  of  foliage  and  flowers,  just  as, 
during  the  long  lapse  of  ages,  she  reconstitutes  her  seas  and  her  continents, 
and  moves  them  slowly  over  her  surface. 


THE     END. 


\ 


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respecting  the  Primordial  Condition  and  the  Ultimate  Destiny  of  the  Earth  and 
the  Solar  System.  By  Alexanpeb  Winciieli,,  LL.D.,  Professor  of  Geology, 
Zoology,  and  Botany  in  the  University  of  Michican,  and  Director  of  the  State 
Geological  Survey.    With  Illustrations.    12rao,  Cloth,  $2  00. 


WHITE'S  MASSACRE  OF  ST.  BARTHOLOMEW.  The  Massacre  of  8t  Bartholo- 
mew :  Preceded  by  a  Historv  of  the  Religious  Wars  in  the  Reign  of  Charles  IX. 
By  He.nbv  White,  M.A.    With  Illustrations.    8vo,  Cloth,  $1  76. 


2  Harper  6-  Brothers'  Valuable  Standard  Works. 

LOSSING'S  FIELD-BOOK  OF  THE  REVOLUTION.  Pictorial  Field-Book  of  the 
Eevolntion;  or,  Illustrations,  by  Pen  and  Pencil,  of  the  History,  Biography, 
Scenery,  Relics,  and  Traditions  of  the  War  for  Independence.  By  Benson  J. 
L088INO.  2  vols.,  8vo,  Cloth,  $14  00;  Sheep,  $15  00;  Half  Calf,  $18  00;  Full 
Turkey  Morocco,  $22  00. 

LOSSING'S  FIELD-BOOK  OF  THE  WAR  OF  1812.  Pictorial  Field-Book  of  the 
War  of  1812;  or.  Illustrations,  by  Pen  and  Pencil,  of  the  History,  Biography, 
Scenery,  Relics,  and  Traditions  of  the  Last  War  for  American  Independence.  By 
Benson  J.  Lossino.  With  several  hundred  Engravings  on  Wood,  by  Lossing  and 
Barritt,  chiefly  from  Original  Sketches  by  the  Author.  1088  pages,  Svo,  Cloth, 
$T00;  Sheep,  $8  50;  Half  Calf,  $10  00. 

ALFORD'S  GREEK  TESTAMENT.  The  Greek  Testament :  with  a  critically  revised 
Text;  a  Digest  of  Various  Readings;  Marginal  References  to  Verbal  and'Idio- 
matic  Usage ;  Prolegomena ;  and  a  Critical  and  Exe^etical  Commentary.  For 
the  Use  of  Theological  Students  and  Ministers.  By  Henry  Alfoed,  D.D.,  Dean 
of  Canterbury.  Vol.  I.,  containing  the  Four  Gospels.  944  pages,  Svo,  Cloth, 
$6  00 ;  Sheep,  $6  50. 

ABBOTT'S  FREDERICK  THE  GREAT.  The  History  of  Frederick  the  Second, 
called  Frederick  the  Great.  By  Joun  S.  C.  Aubott,  Elegantly  Hlustrated.  Svo, 
Cloth,  $5  00. 

ABBOTT'S  HISTORY  OP  THE  FRENCH  REVOLUTION.  The  French  Revolu- 
tion of  1789,  as  viewed  in  the  Light  of  Republican  Institutions.  By  Joun  S.  C.  Ab« 
BOTT.    With  100  Engravings.    Svo,  Cloth,  $5  00. 

ABBOTT'S  NAPOLEON  BONAPARTE.  The  History  of  Napoleon  Bonaparte.  By 
John  S.  C.  Auijott.  With  Maps,  Woodcuts,  and  Portraits  on  Steel.  2  vols., 
Svo,  Cloth,  $10  00. 

ABBOTT'S  NAPOLEON  AT  ST.  HELENA ;  or,  Interesting  Anecdotes  and  Remark- 
able Conversations  of  the  Emperor  during  the  Five  and  a  Half  Years  of  his 
Captivity.  Collected  from  the  Memorials  of  Las  Casas,  O'Meara,  Montholon, 
Antommarchi,  and  others.  By  John  S.  C.  Abbott.  With  Illustrations.  Svo, 
Cloth,  $5  00. 

ADDISON'S  COMPLETE  WORKS.  The  Works  of  Joseph  Addison,  embracing  the 
whole  of  the  "Spectator."    Complete  in  3  vols.,  Svo,  Cloth,  $6  00. 

ALCOCK'S  JAPAN.  The  Capital  of  the  Tycoon :  a  Narrative  of  a  Three  Years' 
Residence  in  Japan.  By  Sir  Rutuekford  Alcock,  K.C.B.,  Her  Majesty's  Envoy 
Extraordinary  and  Minister  Plenipotentiary  in  Japan.  With  Maps  and  Engravings. 
2  vols.,  ]2mo.  Cloth,  $3  50. 

ALISON'S  HISTORY  OF  EUROPR  First  Series  :  From  the  Commencement  of 
the  French  Revolution,  in  1789,  to  the  Restoration  of  the  Bourbons,  in  1815.  [In 
addition  to  the  Notes  on  Chapter  LXXVI.,  which  correct  the  errors  of  the 
original  work  concerning  the  United  States,  a  copious  Analytical  Index  has  been 
appended  to  this  American  edition.]  Second  Series  :  From  the  Fall  of  Napoleon, 
in  1815,  to  the  Accession  of  Louis  Napoleon,  in  1852.    S  vols.,  Svo,  Cloth,  $16  00. 

BALDWIN'S  PRE-HISTORIC  NATIONS.  Pre-Historic  Nations ;  or.  Inquiries  con- 
cerning some  of  the  Great  Peoples  and  Civilizations  of  Antiquity,  and  their 
Probable  Relation  to  a  still  Older  Civilization  of  the  Ethiopians  or  Cushites  of 
Arabia.  By  John  D.  Baldwin,  Member  of  the  American  Oriental  Society. 
12mo,  Cloth,  $1  75. 

EARTH'S  NORTH  AND  CENTRAL  AFRICA.  Travels  and  Discoveries  in  North 
and  Central  Africa:  being  a  Journal  of  an  Expedition  undertaken  nnder  th» 
Auspices  of  H.  B.  M.'s  Government,  in  the  Years  1849-1855.  By  Henbt  Babth, 
Ph.D.,  D.C.L.    Illustrated.    3  vols.,  Svo,  Cloth,  $12  00. 

HENRY  WARD  BEECHER'S  SERMONS.  Sermons  by  Henrt  Ward  Beeouer, 
Plymouth  Church,  Brooklyn.  Selected  from  Published  and  Unpublished  Dis- 
courses, and  Revised  by  their  Author.  With  Steel  Portrait.  Complete  in  2  vols., 
Svo,  Cloth,  $6  00. 

LYMAN  BEECHER'S  AUTOBIOGRAPHY,  &o.  Autobiography,  Correspondence, 
Ac,  of  Lyman  Beecher,  D.D.  Edited  by  his  Son,  Charles  Beecher.  M'ith  Three 
Steel  Portraits,  and  Engravings  on  Wood.    In  2  vols.,  12mo,  Cloth,  $5  00. 

BOSWELL'S  JOHNSON.  The  Life  of  Samuel  Johnson.  LL.D.  Including  a  Journey 
to  the  Hebrides.  By  James  Boswell,  Esq.  A  New  Edition,  with  numerous 
Additions  and  Notes.  By  John  Wilson  Cbokeb,  LL.D.,  F.R.S.  Portrait  of 
BoBwelL    2  vols.,  Svo,  Cloth,  $4  00. 


Harper  6-  Brothers'  Valuable  Standard  Works.  3 

DRAPER'S  CIVIL  WAR  History  of  the  American  Civil  War.  By  John  W.  Dba- 
PEE,  M.D.,  LL..D.,  Professor  of  Chemistry  and  Physiology  In  the  University  of 
New  Yorlc    In  Three  Vols.    8vo,  Cloth.  $3  50  per  vol. 

DRAPER'S  INTELLECTFAL  DEVELOPMENT  OF  EUROPK  A  History  of  the 
Intellectual  Development  of  Europe.  By  John  W.  Duai-kb,  M.D.,  LL.D.,  Profess- 
or of  Chemistry  ana  Physiolojjy  in  the  Uuiwsity  of  New  York-    Svo,  Cloth,  $6  00. 

DRAPER'S  AMERICAN  CIVIL  POLICY,  'ffoughts  on  the  Future  CivU  Policy  of 
America.  By  John  W.  Dbaper,  M.D.,  LL.D.,  Professor  of  Chemistry  and  Physiol- 
ogy in  the  University  of  New  York.    Crown  Svo,  Cloth,  $2  50. 

DU  CHAILLU'S  AFRICA.  Explorations  and  Adventures  in  Equatorial  Africa :  with 
Accounts  of  the  Manners  and  Customs  of  the  People,  and  of  the  Chase  of  the  Go- 
rilla, the  Crocodile,  Leopard,  Elephant,  Hippopotamus,  and  other  Animals.  By 
Pacl  B.  Dd  CuAiLLU.  Numerous  Illustrations.    Svo,  Cloth,  $5  00. 

BELLOWS'S  OLD  WORLD.  The  Old  World  in  its  New  Face :  Impressions  of  Eu- 
rope in  1S6T-186S.    By  Heney  W.  Bellows.    2  vols.,  12mo,  Cloth,  $3  60. 

BROD  HEAD'S  HISTORV  OPTTIiW  YORK.  History  of  the  State  of  Ne>f  York. 
By  JouN  RoMEYN  Bkodueau.    1609-lCai.    2  vols.    Svo,  Cloth,  $3  00  per  vol. 

BROUGHAM'S  AUTOBIOGRAPHY.  Life  and  Times  of  Henbt,  Loep  BBonoHAM. 
Written  by  Himself.    In  Three  Volumes.    12mo,  Cloth,  $2  00  per  voL 

BULWER'S  PROSE  WORKS.  Miscellaneous  Prose  Works  of  Edward  Bulwer, 
Lord  Lytton.    2  vols.,  12rao,  Cloth,  $3  60. 

BULWER'S  HORACB  The  Odes  and  Epodes  of  Horace.  A  Metrical  Translation 
into  English.  With  Introduction  and  Commentaries.  By  Loed  Lytton.  With 
Latin  Text  from  the  Editions  of  Orelli,  Macleane,  and  Yonge.    12mo,  Cloth,  $1  75. 

BULWER'S  KING  ARTHUR.  A  Poem.  By  Eabl  Lytton.  New  Edition.  12mo, 
Cloth,  $1  75. 

BURNS'S  LIFE  AND  WORKS.  The  Life  and  Works  of  Robert  Bums.  Edited 
by  RoBEUT  CuAMBEKS.    4  vols.,  12mo,  Cloth,  $6  00. 

REI^EER,  DOGS,  AND  SNOW-SHOES.  A  Journal  of  Siberian  Travel  and  Ex- 
plorations made  in  the  Years  1865-'67.  By  Riohaed  J.  Bush,  late  of  the  Russo- 
American  Telegraph  Expedition.    Illustrated.    Crown  Svo,  Cloth,  $3  00. 

CARLYLE'S  FREDERICK  THE  GREAT.  History  of  Friedrich  II.,  called  Frederick 
the  Great.  By  Thomas  Cablyle.  Portraits,  Maps,  Plans,  &c.  C  vols.,  12mo, 
Cloth,  $12  00. 

CARLYLE'S  FRENCH  REVOLUTION.  History  of  the  French  Revolution.  Newly 
Revised  by  the  Author,  with  Iiylex,  &c.    2  vols.,  12mo,  Cloth,  $3  60. 

CARLYLE'S  OLIVER  CROMWELL.  Letters  and  Speeches  of  Oliver  CromwelL 
With  Elucidations  and  Connecting  Narrative.    2  vols.,  12mo,  Cloth,  $3  60. 

CHALMERS'S  POSTHUMOUS  WORKS.  The  Posthumous  Works  of  Dr.  Chalmers. 
Edited  by  his  Sou-in-Law,  Rev.  William  Hanna,  LL.D.  Complete  in  9  vols., 
12mo,  Cloth,  $13  60. 

COLERIDGE'S  COMPLETE  WORKS.  The  Complete  Works  of  Samuel  Taylor 
Coleridge.  With  an  Introductory  Essay  upon  his  Philosophical  and  Theological 
Opinions.  Edited  by  Professor  Shbdd.  Complete  in  Seven  Vols.  With  a  flue 
Portrait.    Small  Svo,  Cloth,  $10  80. 

CURTIS'S  HISTORY  OF  THE  CONSTITUTION.  History  of  the  Origin,  Formation, 
and  Adoption  of  the  Constitution  of  the  United  States.  By  Geoboe  Ticknob 
CiRTis.    2  vols.,  Svo,  Cloth,  $G  00. 

DOOLITTLE'S  CHINA.  Social  Life  of  the  Chinese :  with  some  Account  of  their  Re- 
ligious, Governmental,  Educational,  and  Business  Customs  and  Opinions.  With 
special  but  not  exclusive  Reference  to  Fuhchnu.  By  Rev.  Jusrrs  Doolittle, 
Fourteen  Years  Member  of  the  Fuhchan  Mission  of  the  American  Board.  Illus- 
trated with  more  than  150  characteristic  Engravings  on  Wood.  2  vols.,  12mo, 
Cloth,  $5  00. 

GIBBON'S  ROME.  History  of  the  Decline  and  Fall  of  the  Roman  Empire.  By  Ed- 
WAEii  Gibbon.  With  Notes  by  Rev.  H.  H.  Mii.man  and  M.  GnzoT.  A  new  cheap 
Edition.  To  which  is  added  a  complete  Index  of  the  whole  Work,  and  a  Portrait 
of  the  Author.    6  vols.,  12mo,  Clotn,  $9  00. 


4  Harper  &*  Brothers'  Valuable  Standard  Works. 

HARPER'S  NEW  CLASSICAL  LIBRARY.    Literal  Translations. 

The  following  Volumes  are  now  ready.    Portraits.    12mo,  Cloth,  $1  50  each. 

C.£8AB.  — VlROlL.  —  SaLLCBT.  —  HoRAOE.—  ClCEUO'S  ORATIONS. — ClOKRO'S  OfFIOEFj 

&c — CioEEO  ON  Oratory  and  Orators.— Tacitus  ('2  vols.).  —  Terence. — 
SoPUOCLES. — Juvenal. — Xenopuon. —  Homer's  Iliad. — Homkr's  OnvssEY. — 
Herodotus. — Demostuenes.— ^uucydides. — .^Escuylus. — Euripides  (2  vols.). 
— LivY  (2  vols.).  ^ 

DAVIS'S  CARTHAGE.  Carthage  and  her  Remains :  being  an  Account  of  the  Exca- 
vations and  Researches  on  the  Site  of  the  Phoenician  Metropolis  in  Africa  and  other 
adjacent  Places.  Conducted  under  the  Auspices  of  Her  Majesty's  Government. 
Bv  Dr.  Davis,  F.R.G.S.  Profusely  Illustrated  with  Maps,  Woodcuts,  Chromo- 
Lithographs,  &c.    8vo,  Cloth,  $4  00. 

EDGE  WORTH'S  (Miss)  NOVELS.   With  Engravings.    10  vols.,  12mo,  Cloth,  $16  00. 

GROTE'S  HISTORY  OF  GREECE.    12  vols.,  12mo,  Cloth,  $18  00. 

HELPS'S  SPANISH  CONQUEST.  The  Spanish  Conquest  in  America,  and  itsRela- 
tion,to  the  History  of  Slavery  and  to  the  Government  of  Colonies.  By  Abtbub 
Helps.    4  vols.,  12mo,  Cloth,  $6  00. 

HALE'S  (Mrs.)  WOMAN'S  RECORD.  Woman's  Record ;  or,  Biographical  Sketches 
of  all  Distinguished  Women,  from  the  Creation  to  the  Present  Time.  Arranged 
in  Four  Eras,  with  Selections  from  Female  Writers  of  each  Era.  By  Mrs.  Saeau 
JosEPiiA  Hale.    Illustrated  with  more  than  200  Portraits.    8vo,  Cloth,  $5  00. 

HALL'S  ARCTIC  RESEARCHES.  Arctic  Researches  and  Life  among  the  Esqui- 
maux :  being  the  Narrative  of  an  Expedition  in  Search  of  Sir  John  Franklin,  in 
the  Years  18()0, 1861,  and  1862.  By  Charles  Francis  Hall.  With  Maps  and  100 
Illustrations.  The  Illustrations  are  from  Original  Drawings  by  Charles  Parsons, 
Henry  L.  Stephens,  Solomon  Eytinge,  W.  S.  L.  Jewett,  and  Granville  Perkins, 
after  Sketches  by  Captain  Hall.    8vo,  Cloth,  $5  00. 

HALLAM'S  CONSTITUTIONAL  HISTORY  OF  ENGLAND,  fi-om  the  Accession  of 
Henry  VIL  to  the  Death  of  George  IL    8vo,  Cloth,  $2  00. 

HALLAM'S  LITERATURE.  Introduction  to  the  Literature  of  Europe  during^the 
Fifteenth,  Sixteenth,  and  Seventeenth  Centuries.  By  Heney  Hallam.  2  vols., 
8vo,  Cloth,  $4  00. 

HALLAM'S  MIDDLE  AGES.  State  of  Europe  during  the  Middle  Ages.  By  Henbt 
Hallam.    8vo,  Cloth,  $2  00. 

HILDRETH'S  HISTORY  OF  THE  UNITED  STATES.  First  Series  :  From  the 
First  Settlement  of  the  Country  to  the  Adoption  of  the  Federal  Constitution. 
Second  Series  :  From  the  Adoption  of  the  Federal  Constitution  to  the  End  of 
the  Sixteenth  Congress.     6  vols.,  8vo,  Cloth,  $18  00. 

HUME'S  HISTORY  OF  ENGLAND.  History  of 'England,  from  the  Invasion  of  Ju- 
lius Caesar  to  the  Abdication  of  James  II.,  16S8.  By  David  Hume.  A  new  Edi- 
tion, with  the  Author's  last  Corrections  and  Improvements.  To  which  is  Prefix- 
ed a  short  Account  of  his  Life,  written  by  Himself.  With  a  Portrait  of  the  Au- 
thor.   6  vols.,  12mo,  Cloth,  $9  00. 

JAY'S  WORKS.  Complete  Works  of  Rev.  William  Jay :  comprising  his  Sermons, 
Family  Discourses,  Morning  and  Evening  Exercises  for  every  Day  in  the  Year, 
Family  Prayers,  &c.  Author's  enlarged  Edition,  revised.  3  vols.,  8vo,  Cloth, 
$6  00. 

JEFFERSON'S  DOMESTIC  LIFE.  The  Domestic  Life  of  Thomas  Jefferson :  com- 
piled from  Family  Letters  and  Reminiscences  by  his  Great-Granddaughter, 
Sarah  N.  Randolph.  With  Illustrations.  Crown  8vo,  Illuminated  Clothi,  Bev- 
eled Edges,  $2  80. 

JOHNSON'S  COMPLETE  WORKS.  The  Works  of  Samuel  Johnson,  LL.D.  With 
an  Essay  on  his  Life  and  Genius,  by  Abthub  Murphy,  Esq.  Portrait  of  Johnson. 
2  vols.,  8vo,  Cloth,  $4  00. 

'KINGLAKE'S  CRIMEAN  WAR.  The  Invasion  of  the  Crimea,  and  an  Account  of 
its  Progress  dovpn  to  the  Death  of  Lord  Raglan.  By  Alexander  William  Kino- 
lake.     With  Maps  and  Plans.    Two  Vols,  ready.    12mo,  Cloth,  $2  00  per  vol. 

KINGSLEY'S  WEST  INDIES.  At  Last:  A  Christmas  in  the  West  Indies.  By 
Charles  Kinosley.    Illustrated.    12mo,  Cloth,  $1  50. 


Harper  6f  Brothers'  Valuable  Standard  Works.  5 

KRUMMACHER'S  DAVID,  KING  OF  ISRAEL.  David,  the  King  of  Israel:  a  Por- 
trait drawn  from  Bible  History  and  the  Book  of  Psalms.  By  Fbekebiok  William 
Kbcmmaoueb,  D.D.,  Author  of  "Elijah  the  Tishbite/'  &c  .  Translated  under  the 
express  Sanction  of  the  Author  by  the  Rev.  M.  G.  Easton,  M.A.  With  a  Letter 
from  Dr.  Krummacher  to  his  American  Readers,  and  a  Portrait.  12mo,  Cloth, 
$175.  ^ 

LAMB'S  COMPLETE  WORKS.  The  Works  of  Charles  Lamb.  Comprisinahis  Let- 
ters, Poems,  Essavs  of  Elia,  Essays  npon  Sbakspeare,  Hogarth,  &&,  and  a  Sketch 
of  his  Life,  with  the  Final  Memorials,  by  T.  Noon  Talfoukd.  Portrait.  2  vols., 
12mo,  Cloth,  $3  00. 

LIVINGSTONE'S  SOUTH  AFRICA.  Missionary  Travels  and  Researches  in  South 
Africa;  including  a  Sketch  of  Sixteen  Years'  Residence  in  the  Interior  of  Africa, 
and  a  Journey  from  the  Cape  of  Good  Hope  to  Loando  on  the  West  Coast  r  thence 
across  the  Continent,  down  the  River  Zambesi,  to  the  Eastern  Ocean.  By  David 
LnriNosTONB,  LL.D.,  D.C.L.  With  Portrait,  Maps  by  Arrowsmith,  and  numerous 
Illustrations.    8vo,  Cloth,  $4  50. 

LIVINGSTONES'  ZAMBESI.  Narrative  of  an  Expedition  to  the  Zambesi  and  its 
Tributaries,  and  of  the  Discovery  of  the  Lakes  Shimva  and  Nyassa.  1868-1864. 
By  David  and  Cuasles  Livisostone.  With  Map  and  Illustrations.  8vo,  Cloth, 
$500. 

M'CLINTOCK  A  STRONG'S  CYCLOPAEDIA.  Cyclopaedia  of  Biblical,  Theological, 
and  Ecclesiastical  Literature.  Prepared  by  the  Rev.  Joun  M'Clistock,  D.D., 
and  James  Stkosg,  S.T.D.  3  vols,  nmu  ready.  Royal  Svo.  Price  per  voL,  Cloth, 
$5  00 ;  Sheep,  $6  00 ;  Half  Morocco,  $8  00. 

MARCY'S  army  LIFE  ON  THE  BORDER.  Thirty  Years  of  Army  Life  on  the 
Border.  Comprising  Descriptions  of  the  Indian  Nomads  of  the  Plains ;  Explo- 
rations of  New  Territory;  a  Trip  across  the  Rocky  Mountains  in  the  Winter; 
Descriptions  of  the  Habits  of  Different  Animals  found  in  the  West,  and  the  Meth- 
ods of  Hunting  them  ;  with  Incidents  in  the  Life  of  Different  Frontier  Men,  Ac., 
&c  Bv  Brevet  Brigadier-General  R.  B.  Maecy,  U.S.A.,  Author  of  "  The  Prairie 
Traveller."    With  numerous  Illustrations.    Svo,  Cloth,  Beveled  Edges,  $3  00. 

MACAULAY'S  HISTORY  OF  ENGLAND.  The  History  of  England  from  the  Ac- 
cession of  James  EL  By  Thomas  Babington  MAOArLAY.  With  an  Original  Por- 
trait of  the  Author.    5  vols.,  Svo,  Cloth,  $10  00 ;  12mo,  Cloth,  $T  50. 

MOSHEIM'S  ECCLESIASTICAL  HISTORY,  Ancient  and  Modem ;  in  which  the 
Rise,  Progress,  and  Variation  of  Church  Power  are  considered  in  their  Connec- 
tion with  the  State  of  Learning  and  Philosophy,  and  the  Political  History  of  Eu- 
rope during  that  Period.  Translated,  with  Notes,  &c.,  by  A.  Maclaike,  D.D. 
A  new  Edition,  continued  to  1826,  by  C.  Coote,  LL.D.    2  vols.,  Svo,  Cloth,  $4  00. 

NEVIUS'S  CHINA.  China  and  the  Chinese:  a  General  Description  of  the  Country 
and  its  Inhabitants;  its  Civilization  and  Form  of  Goveniment;  its  Religious  and 
Social  Institutions ;  its  Intercourse  with  other  Nations ;  and  its  Present  Condition 
and  Prospects.  By  the  Rev.  John  L.  Nrvirs,  Ten  Yeartf  a  Missionary  in  China. 
With  a  If&p  and  Illustrations.    12mo,  Cloth,  $1  75. 

OLIN'S  (Db.)  life  and  LETTERS.    2  vols.,  12mo,  Cloth,  $3  00. 

OLIN'S  (Dk.)  travels.  Travels  in  Egypt,  Arabia  Petrsea,  and  the  Holy  Land.  En- 
gravings.   2  vols.,  Svo,  Cloth,  $3  00. 

OLIN'S  (Dr.)  works.  The  Works  of  Stephen  Olin,  D.D.,  late  President  of  the  Wes- 
leyan  University.    2  vols.,  12mo,  Cloth,  $3  00. 

OLIPH  ANT'S  CHINA  AND  JAPAN.  Narrative  of  the  Earl  of  Elgin's  Mission  to 
China  and  Japan,  in  the  Years  1867,  '58,  '60.  By  Laitrence  OurnAST,  Private 
Secretary  to  Lord  Elgin.    Dlustrations.    Svo,  Cloth,  $3  60. 

OLIPHANT8  (Mrs.)  LIFE  OF  EDWARD  IRVING.  The  Life  of  Edward  Irving, 
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Correspondence.    By  Mrs.  Oliphant.    Portrait.    Svo,  Cloth,  $3  50. 

EAWLINSON'S  MANUAL  OF  ANCIENT  HISTORY.  A  Manual  of  Ancient  His- 
torv,  from  the  Earliest  Times  to  the  Fall  of  the  Western  Empire.  Comprising 
the' History  of  Chaldaea,  Assyria,  Media,  Babylonia,  Lvdia,  Phoenicia,  Syria,  Ju- 
daea, E^pt,  Carthage,  Persia*  Greece,  Macedonia,  Parthia,  and  Rome.  By 
Gkobor  Rawumson.M.A.,  Camden  Professor  of  Ancient  History  in  the  Univer- 
sity of  Oxford.    12mo,  Cloth,  $2  50. 


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Am^ican  Additions,  arranged  by  Evert  A.  Dutckinok,  Editor  of  "  Cyclopiedia 
of  Aierican  Literature."  Comprising  Selections  from  the  Greatest  Authors  of 
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SMILES'S  HISTORY  OF  THE  HUGUENOTS.  The  Hngnenots :  their  Settlements, 
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SPEKE'S  AFRICA.  Journal  of  the  Discovery  of  the  Source  of  the  Nile.  By  Cap- 
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alist of  the  Royal  Geographical  Society,  Hon.  Corresponding  Member  and  Gold 
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Characteristic  Portraits.    8vo,  Paper,  76  cents ;  Cloth,  $1  25. 

THOMSON'S  LAND  AND  THE  BOOK.  The  Land  and  the  Book ;  or,  Biblical  Illus- 
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TYERMAN'S  WESLEY.  The  Life  and  Times  of  the  Rev.  John  Wesley,  M.  A.,  Found- 
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Caspian,  to  Khiva,  Bokhara,  and  Samarcand,  performed  in  the  Year  1863.     By 

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WOOD'S  HOMES  WITHOUT  HANDS.  Homes  Without  Hands :  being  a  Descrip- 
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